Photovoltaic Systems
Remake batch 25 and its neighbor re-points, batch 24 where missing, and the adopted-electrical-code parameter: brought in line with the authoring repository
Showing changes from Rev 3
to Rev 4
in Photovoltaic Systems.
---
title: Photovoltaic Systems
category: Electrical
−toc_depth: 3
description: >
− When to use: Roof-mounted and ground-mounted solar photovoltaic (PV) electric power systems for commercial, institutional, industrial, and multifamily buildings, sized from a few kilowatts to multiple megawatts and interconnected with the building electrical system and, through it, the serving utility. Covers PV modules; string, central, and module-level (microinverter and DC optimizer) inverter topologies; DC and AC conductors and overcurrent protection; rapid shutdown and arc-fault protection; equipment grounding and bonding; surge protection; mounting and racking for ballasted flat-roof, attached/flashed-penetration, and standing-seam metal-clamp roofs and for fixed-tilt and single-axis-tracker ground mounts; rooftop fire-service access pathways and setbacks; revenue-grade production metering and monitoring; and the load-side and supply-side interconnection paths governed by NFPA 70 Articles 690 and 705.
− Not intended for: Utility-scale large-scale PV electric supply stations under the exclusive control of an electric utility (NFPA 70 Article 691); the battery energy storage system itself, its enclosure, thermal management, and battery management, which is a separate scope (see [[sync/battery-energy-storage-systems]]); the building site civil, structural, and geotechnical engineering that establishes roof and foundation load capacity, which is a separate licensed-engineer scope referenced but not specified here; off-grid and stand-alone power systems with no utility interconnection; and solar thermal (hot water) collectors, which are not electric power production sources.
+ When to use: Grid-interactive photovoltaic power systems on and around commercial, institutional, industrial, and multifamily buildings and campuses, from a few kilowatts to several megawatts, on a roof, on the ground, or on a carport or canopy, interconnected with the premises wiring under NFPA 70 Articles 690 and 705, including a multimode system whose storage is specified separately. Covers the modules and the cell technology, the inverters and the power conversion architecture, the maximum DC voltage, rapid shutdown and arc-fault protection, the DC source and output circuits, their combiners, connectors, overcurrent protection, and PV-specific disconnects, DC surge protection, the method and the application for interconnection with the utility, the mounting system as a delegated design on a roof, on the ground, or on a canopy, the bonding of modules and racking, production metering and monitoring, commissioning to IEC 62446-1, performance acceptance, the production guarantee, the warranties, and the spares.
+
+ Not intended for: the battery energy storage system, its power conversion system, its enclosure, and its hazard mitigation (see [[sync/battery-energy-storage-systems]]); a utility-owned generating station under NFPA 70 Article 691; a stand-alone system with no utility interconnection; solar thermal collectors; the capacity of the roof structure, the soil, and the foundations, which the structural engineer of record and the geotechnical engineer establish; the utility service, the service disconnecting means, and the metering of the service (see [[sync/electrical-service-entrance]]); the general-purpose enclosed switch and enclosed circuit breaker applied as a disconnecting means elsewhere on the premises (see [[sync/enclosed-switches-and-disconnects]]); building wire, feeders, and raceways beyond the array (see [[sync/conductors-and-cables]], [[sync/raceways-and-conduit]], [[sync/underground-ductbank]]); the grounding electrode system and the general rules for equipment grounding conductors (see [[sync/grounding-and-bonding]]); the lightning protection system (see [[sync/lightning-protection]]); the surge protective device at the AC point of interconnection as a product (see [[sync/surge-protective-devices]]); the switchboard or panelboard the system lands on (see [[sync/low-voltage-switchboards]], [[sync/panelboards]]); the isolation and step-up transformers (see [[sync/low-voltage-dry-type-transformers]], [[sync/medium-voltage-transformers]]); the fault, coordination, and arc-flash studies (see [[sync/short-circuit-study]], [[sync/protective-coordination-study]], [[sync/arc-flash-study]]); the testing firm, its instruments, and its report (see [[sync/electrical-acceptance-testing]]); the flashing of roof penetrations and the roof covering itself (see [[sync/membrane-roofing]]); the metal roof covering and the confirmation that it can carry the reactions of the attachments (see [[sync/metal-roof-panels]]); the piles and piers of a ground mount as constructed (see [[sync/deep-foundations]]); the steel structure of a carport or canopy (see [[sync/structural-steel-framing]]); the concrete pad under an inverter or a transformer (see [[sync/concrete-pads]]); the meters as products (see [[sync/electrical-power-monitoring]]); label material and lettering (see [[sync/equipment-labeling]]); the network cabling (see [[sync/structured-cabling]]); and electric vehicle supply equipment and its circuits (see [[sync/electric-vehicle-charging]]).
---
# Scope {toc}
−## This standard covers the materials, ratings, configuration, mounting, installation, and testing of grid-interconnected photovoltaic (PV) electric power systems for buildings. {note}
+## This standard governs the photovoltaic system as an electric power production source and the work that puts it into service: the modules, the inverters and the module-level electronics, the DC source and output circuits with their combiners, connectors, fuses, and disconnects, the rapid shutdown and arc-fault protection, the DC surge protection, the point and the method of interconnection with the premises wiring, the application to the serving utility and its permission to operate, the mounting system as a delegated design, the bonding of the array, the production meter and the monitoring, the commissioning tests, the performance acceptance, and the production guarantee, the warranties, and the spares. {note}
−## The work includes PV modules, inverters, DC and AC conductors and overcurrent protection, rapid-shutdown and arc-fault protection, grounding and bonding, surge protection, mounting and racking, revenue-grade production metering, monitoring, and the equipment required to interconnect the PV system with the building electrical system. {note}
+## A photovoltaic system is governed by NFPA 70 Article 690 for everything from the module to the inverter output and by Article 705 for the connection of that output to a premises that already has a utility source; the building code and the fire code govern the array as a rooftop load, as a fire exposure, and as an obstacle to the fire department, and the serving utility governs the interconnection through its tariff and the IEEE 1547 settings it assigns. The equipment listings prove each product; the Article 690 calculations, the delegated racking design, and the interconnection agreement prove the system. {note}
−## A photovoltaic system converts solar irradiance into DC electricity at the modules and, through one or more inverters, into AC power that is interconnected with the building distribution system and the serving utility. {note}
+## The cell technology, the power conversion architecture, the rapid shutdown method, the mounting type, and the interconnection method are independent decisions and are carried as independent selections; every combination is built, and no selection here implies another. {note}
−## PV systems shall be designed, furnished, and installed in accordance with NFPA 70 (the National Electrical Code) Article 690 and, for the interconnection, Article 705.
+## The array size in kilowatts DC and AC, the module count, the string lengths, the tilt, the azimuth, the row spacing, and the layout of the array are project-sized values that live on the photovoltaic drawings, and the capacity of the roof, the soil, and the foundations is established by the structural engineer of record and the geotechnical engineer; this standard requires that those documents exist and that the work follows them, and it does not restate them. {note}
−## PV systems shall comply with the edition of NFPA 70 adopted by the Authority Having Jurisdiction (AHJ).
+## The following are governed elsewhere and are outside this standard: {note}
−## The adopted NEC edition shall be confirmed in writing with the AHJ before the design is finalized, because Article 690 changed materially between the 2017, 2020, and 2023 editions in the areas of rapid shutdown, arc-fault protection, and DC surge protection. {note}
+- the battery energy storage system, its power conversion system, its enclosure, and its hazard mitigation, under [[sync/battery-energy-storage-systems]]
+- the utility service, the service disconnecting means, and the metering of the service, under [[sync/electrical-service-entrance]]
+- the general-purpose enclosed switch and enclosed circuit breaker applied as a disconnecting means elsewhere on the premises, under [[sync/enclosed-switches-and-disconnects]]
+- building wire, feeders, and raceways beyond the array, under [[sync/conductors-and-cables]], [[sync/raceways-and-conduit]], and [[sync/underground-ductbank]]
+- the grounding electrode system, the auxiliary electrode at an array, and the general rules for equipment grounding conductors, under [[sync/grounding-and-bonding]]
+- the lightning protection system, under [[sync/lightning-protection]]
+- the surge protective device at the AC point of interconnection as a product, under [[sync/surge-protective-devices]]
+- the switchboard or panelboard the system lands on, under [[sync/low-voltage-switchboards]] and [[sync/panelboards]]
+- the isolation transformer and the step-up transformer, under [[sync/low-voltage-dry-type-transformers]] and [[sync/medium-voltage-transformers]]
+- the fault, coordination, and arc-flash studies, under [[sync/short-circuit-study]], [[sync/protective-coordination-study]], and [[sync/arc-flash-study]]
+- the testing firm, its instruments, and its report, under [[sync/electrical-acceptance-testing]]
+- the flashing of roof penetrations and the roof covering itself, under [[sync/membrane-roofing]], and the metal roof covering and the confirmation that it can carry the reactions of the attachments, under [[sync/metal-roof-panels]]
+- the piles and piers of a ground mount as constructed, under [[sync/deep-foundations]], and the steel structure of a carport or canopy, under [[sync/structural-steel-framing]]
+- the concrete pad under an inverter or a transformer, under [[sync/concrete-pads]]
+- the meters as products, under [[sync/electrical-power-monitoring]], and the building automation system that reads the production data, under [[sync/building-automation-system]]
+- label material and lettering, under [[sync/equipment-labeling]]
+- the network cabling, under [[sync/structured-cabling]]
+- electric vehicle supply equipment and its circuits, under [[sync/electric-vehicle-charging]]
+- the classification of loads and the transfer scheme where a multimode system serves a life-safety load, under [[sync/emergency-and-standby-power]]
+- the anchors for fall protection during maintenance of the array, under [[sync/fall-protection-anchorage]]
−## Where the contract documents, the adopted codes, or a referenced standard conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
+## A utility-owned generating station under NFPA 70 Article 691, a stand-alone system with no utility interconnection, and solar thermal collectors are outside this standard and are not governed by another standard in this library. {note}
−## The Contractor shall coordinate the DC and AC conductors and their overcurrent protection with [[sync/conductors-and-cables]] and [[sync/raceways-and-conduit]].
+## The photovoltaic system shall comply with NFPA 70 Articles 690 and 705 as adopted in [[parameter: adopted-electrical-code]], with the photovoltaic provisions of the adopted building code and fire code, and with the interconnection requirements of the serving utility.
−## The Contractor shall coordinate the equipment grounding and bonding with [[sync/grounding-and-bonding]].
+## The array layout, the module count, the string configuration, the tilt, the azimuth, the row spacing, and the locations of the inverters, combiners, and disconnects shall be as indicated on [[drawing: the photovoltaic plans and the photovoltaic one-line diagram]].
−## The Contractor shall coordinate the DC and AC surge protective devices with [[sync/surge-protective-devices]].
+## Where a value stated on the photovoltaic drawings or the equipment schedules differs from the datasheet selection under this standard, the drawing shall govern for that system.
−## The Contractor shall coordinate all field labeling and placards required by Article 690 with [[sync/equipment-labeling]].
−
−## Large-scale PV electric supply stations under the exclusive control of an electric utility and governed by NFPA 70 Article 691 are outside the scope of this standard. {note}
−
−## A battery energy storage system, where provided, is interfaced with the PV system but is a separate scope; coordination only is addressed here, and the storage equipment is specified under [[sync/battery-energy-storage-systems]]. {note}
−
−## The structural and geotechnical adequacy of the roof, attachments, and ground-mount foundations is a licensed-engineer scope that is referenced but not specified by this standard; nothing in this standard relieves the Contractor of obtaining stamped structural and, for ground mounts, geotechnical engineering. {note}
−
# Referenced Standards {toc}
−## Equipment, materials, and installation shall comply with the latest adopted edition of the following standards and codes.
+## Equipment, materials, and installation shall comply with the latest adopted edition of each of the following unless a specific edition is cited.
+## Where the contract documents, the Authority Having Jurisdiction, the serving utility, or two referenced standards impose conflicting requirements, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
+
| Standard | Title |
|----------|-------|
−| NFPA 70 | National Electrical Code (Article 690 — Solar Photovoltaic Systems; Article 705 — Interconnected Electric Power Production Sources; Article 706 — Energy Storage Systems) |
+| NFPA 70 | National Electrical Code (Articles 110, 250, 300, 310, 690, 705, and 706) |
| NFPA 70E | Standard for Electrical Safety in the Workplace |
−| NFPA 1 | Fire Code (rooftop access and PV system fire-service provisions) |
−| UL 61730-1 / 61730-2 | Photovoltaic (PV) Module Safety Qualification |
−| UL 1703 | Flat-Plate Photovoltaic Modules and Panels (legacy listing standard) |
−| UL 1741 | Inverters, Converters, Controllers and Interconnection System Equipment for Use with Distributed Energy Resources |
−| UL 2703 | Mounting Systems, Mounting Devices, Clamping/Retention Devices, and Ground Lugs for Use with Flat-Plate PV Modules and Panels |
−| UL 3741 | Photovoltaic Hazard Control |
+| NFPA 1 | Fire Code (Section 11.12, Solar Photovoltaic Power Systems) |
+| IFC | International Fire Code (Section 1205, Solar Photovoltaic Power Systems) |
+| IBC | International Building Code (Chapter 15 rooftop photovoltaic provisions and Section 1607 photovoltaic panel system loads) |
+| ASCE/SEI 7 | Minimum Design Loads and Associated Criteria for Buildings and Other Structures (Chapters 13, 29, and 30) |
+| UL 61730-1 | Photovoltaic (PV) Module Safety Qualification, Part 1: Requirements for Construction |
+| UL 61730-2 | Photovoltaic (PV) Module Safety Qualification, Part 2: Requirements for Testing |
+| IEC 61215-1 | Terrestrial Photovoltaic (PV) Modules, Design Qualification and Type Approval, Part 1: Test Requirements |
+| IEC 61215-2 | Terrestrial Photovoltaic (PV) Modules, Design Qualification and Type Approval, Part 2: Test Procedures |
+| IEC TS 62804-1 | Photovoltaic (PV) Modules, Test Methods for the Detection of Potential-Induced Degradation, Part 1: Crystalline Silicon |
+| UL 1741 | Inverters, Converters, Controllers and Interconnection System Equipment for Use With Distributed Energy Resources (including Supplements SA and SB) |
| IEEE 1547 | Standard for Interconnection and Interoperability of Distributed Energy Resources with Associated Electric Power Systems Interfaces |
−| IEEE 1547.1 | Conformance Test Procedures for Equipment Interconnecting Distributed Energy Resources |
−| IEC 61215 | Terrestrial Photovoltaic (PV) Modules — Design Qualification and Type Approval |
−| IEC 61730 | Photovoltaic (PV) Module Safety Qualification |
−| IEC 62109 | Safety of Power Converters for Use in Photovoltaic Power Systems |
−| ASCE/SEI 7 | Minimum Design Loads and Associated Criteria for Buildings and Other Structures |
−| IBC | International Building Code (structural, roof penetrations) |
−| IFC | International Fire Code (Chapter 12 — rooftop access pathways and setbacks) |
−| ANSI C12.20 | Electricity Meters — 0.2 and 0.5 Accuracy Classes |
+| IEEE 1547.1 | Standard Conformance Test Procedures for Equipment Interconnecting Distributed Energy Resources with Electric Power Systems and Associated Interfaces |
+| IEEE 519 | Standard for Harmonic Control in Electric Power Systems |
+| IEEE 2030.5 | Standard for Smart Energy Profile Application Protocol |
+| IEEE 1815 | Standard for Electric Power Systems Communications: Distributed Network Protocol (DNP3) |
+| SunSpec Modbus | SunSpec Alliance Device Information Model Specification and Modbus Interface |
+| UL 3141 | Power Control Systems |
+| UL 3741 | Photovoltaic Hazard Control |
+| UL 1699B | Photovoltaic (PV) DC Arc-Fault Circuit Protection |
+| UL 2703 | Mounting Systems, Mounting Devices, Clamping/Retention Devices, and Ground Lugs for Use with Flat-Plate Photovoltaic Modules and Panels |
+| UL 4703 | Photovoltaic Wire |
+| UL 854 | Service-Entrance Cables |
+| UL 6703 | Connectors for Use in Photovoltaic Systems |
+| UL 248-19 | Low-Voltage Fuses, Part 19: Photovoltaic Fuses |
+| UL 489B | Molded-Case Circuit Breakers, Molded-Case Switches and Circuit-Breaker Enclosures for Use with Photovoltaic (PV) Systems |
+| UL 1449 | Surge Protective Devices |
+| UL 50E | Enclosures for Electrical Equipment, Environmental Considerations |
+| NEMA 250 | Enclosures for Electrical Equipment (1000 Volts Maximum) |
+| IEC 62446-1 | Photovoltaic (PV) Systems, Requirements for Testing, Documentation and Maintenance, Part 1: Grid Connected Systems, Documentation, Commissioning Tests and Inspection |
+| IEC 61724-1 | Photovoltaic System Performance, Part 1: Monitoring |
+| IEC 61724-2 | Photovoltaic System Performance, Part 2: Capacity Evaluation Method |
+| IEC 61724-3 | Photovoltaic System Performance, Part 3: Energy Evaluation Method |
+| ANSI C12.1 | Electric Meters, Code for Electricity Metering |
| ANSI/NETA ATS | Standard for Acceptance Testing Specifications for Electrical Power Equipment and Systems |
+| OSHA 29 CFR 1926 Subpart M | Fall Protection |
−## Where a referenced standard has both a UL and an IEC counterpart, the UL standard governs the US listing and the IEC standard is cited as the performance basis only. {note}
+## UL 1703 was the module listing standard for three decades and is withdrawn for new listings; a module offered today is listed to UL 61730, which is the UL adoption of IEC 61730 with the North American deviations, and a UL 1703 listing on a product data sheet marks either an old design or an old data sheet. IEC 61215 is the design qualification a module passes to prove it survives the thermal cycling, humidity-freeze, mechanical load, and hail of twenty-five years outdoors, and it is cited beside the safety listing because the listing alone does not test endurance. The SunSpec Modbus model is published by an industry alliance rather than a standards body and is cited because IEEE 1547 names it as one of the three interoperability interfaces available to an interactive resource. {note}
−## UL 61730 is the current PV module safety qualification standard and supersedes UL 1703 for new module designs; UL 1703 remains valid only for product already listed to it. {note}
−
−## UL 1741 Supplement SA aligns inverter and interconnection equipment with California Rule 21, while Supplement SB demonstrates compliance with IEEE 1547-2018 and IEEE 1547.1-2020; most commercial interconnections outside California require Supplement SB. {note}
−
−## Confusing UL 1741 Supplement SA with Supplement SB is a common interconnection failure; the serving utility specifies which supplement its tariff requires, and the wrong listing will be rejected at interconnection review. {note}
−
−## ASCE/SEI 7-22 revised the corner and edge wind-uplift coefficients relative to ASCE/SEI 7-16; the racking wind design shall use the edition adopted by the building code in force, because the difference changes ballast and attachment quantities. {note}
−
# Submittals {toc}
## Action Submittals {toc}
−### The Contractor shall submit the following for the Engineer's review prior to procurement and installation:
+### The Contractor shall submit the following for review before any photovoltaic equipment is released for manufacture or purchase:
−- A single-line diagram of the complete PV system showing modules, source and output circuits, combiners, inverters, disconnects, overcurrent devices, the rapid-shutdown system, surge protective devices, metering, and the interconnection point
−- PV module data including the listing (UL 61730 or UL 1703), the electrical ratings at standard test conditions, the temperature coefficients, and the maximum system voltage rating
−- Inverter data including the listing (UL 1741 with the applicable supplement), the topology, the AC and DC ratings, the ground-fault and arc-fault protection, and the rapid-shutdown function
−- Racking and mounting data including the UL 2703 listing, the integrated bonding feature where claimed, and the ballast or attachment schedule
−- Stamped structural calculations for the roof or foundation loads, sealed by a licensed structural engineer, and for ground mounts a geotechnical report
−- Rapid-shutdown system data identifying the method (module-level or listed PV hazard control system per UL 3741), the initiating device, and its location
−- Rooftop fire-service access plan showing setbacks, perimeter pathways, and mid-array aisles
−- Utility interconnection application status and the executed or pending interconnection agreement
−- Revenue-grade production meter data including the ANSI C12.20 accuracy class
−- Manufacturer's installation instructions for modules, inverters, and racking
+- product data for the modules, identifying the manufacturer, the model, the cell technology, the construction, the UL 61730 listing and the IEC 61215 qualification, the fire type, the electrical ratings at standard test conditions and at the nominal module operating temperature, the temperature coefficients of power, voltage, and current, the bifaciality factor where bifacial, the power tolerance, the maximum system voltage, the maximum series fuse rating, and the mechanical load ratings front and rear
+- product data for the inverters and the module-level electronics, identifying the UL 1741 listing and its supplement, the IEEE 1547 categories and functions supported, the DC input voltage window and maximum input current, the AC output voltage, current, and power, the weighted efficiency, the ground-fault, arc-fault, and rapid shutdown functions, the DC surge protection where integral, the enclosure type, and the operating temperature and altitude derating
+- the delegated design of the mounting system: drawings and calculations sealed by an engineer licensed in the state of the project, with the UL 2703 listing of the racking, the system fire class rating with the module furnished, the attachment or ballast layout, the loads delivered to the structure at each attachment or ballast block, and the wind, snow, and seismic loads the design is based on
+- the photovoltaic one-line diagram, showing every source circuit, combiner, output circuit, disconnect, overcurrent device, inverter, module-level electronic device, rapid shutdown device, surge protective device, meter, and the point of interconnection, with the conductor sizes and the voltage and current at each point
+- the array layout plan, showing the module count, the string assignment of every module, the tilt, the azimuth, the row spacing, the fire-service pathways and setbacks on a roof, and the locations of every piece of equipment
+- the maximum voltage calculation under NFPA 70 690.7, the current and ampacity calculations under 690.8, the overcurrent device selection under 690.9, and the voltage drop of the DC and AC circuits
+- the rapid shutdown system data, identifying the method, the devices, the initiator, the array boundary, and, where a hazard control system is furnished, the UL 3741 listing of the specific module, racking, wiring, and inverter combination
+- product data for the production meter, the monitoring system, and the sensors, with a points list of what is recorded and at what interval
+- the energy model, stating the annual production at the fifty percent probability of exceedance, the performance ratio, the losses assumed, the weather file used, and the DC-to-AC ratio
+- the utility interconnection application package as filed, and the interconnection agreement or the utility's conditional approval when received
```datasheet
−label: Action Submittals Required
+label: Action Submittals
type: checkbox
options:
− - "Complete PV system single-line diagram"
− - "PV module data (listing, ratings, temp coefficients, max system voltage)"
− - "Inverter data (listing, topology, ratings, GFP/AFP, rapid shutdown)"
− - "Racking data (UL 2703 listing, bonding, ballast/attachment schedule)"
− - "Stamped structural and geotechnical calculations"
− - "Rapid-shutdown system data (method, initiator, location)"
− - "Rooftop fire-service access plan"
− - "Utility interconnection application status and agreement"
− - "Revenue-grade meter data (ANSI C12.20 class)"
− - "Manufacturer installation instructions"
−default: ["Complete PV system single-line diagram", "PV module data (listing, ratings, temp coefficients, max system voltage)", "Inverter data (listing, topology, ratings, GFP/AFP, rapid shutdown)", "Stamped structural and geotechnical calculations"]
+ - "Module product data"
+ - "Inverter and module-level electronics product data"
+ - "Mounting system delegated design, sealed"
+ - "Photovoltaic one-line diagram"
+ - "Array layout plan"
+ - "Article 690 voltage, current, and overcurrent calculations"
+ - "Rapid shutdown system data"
+ - "Production meter, monitoring, and sensor data"
+ - "Energy model"
+ - "Interconnection application and agreement"
+default:
+ - "Module product data"
+ - "Inverter and module-level electronics product data"
+ - "Mounting system delegated design, sealed"
+ - "Photovoltaic one-line diagram"
+ - "Array layout plan"
+ - "Article 690 voltage, current, and overcurrent calculations"
+ - "Rapid shutdown system data"
+ - "Production meter, monitoring, and sensor data"
+ - "Energy model"
+ - "Interconnection application and agreement"
+constraint: all_of
```
−### Installation of any PV equipment shall not proceed until the corresponding submittals are reviewed and returned.
+### No module, inverter, or racking component shall be released for purchase until the product data, the delegated mounting design, and the one-line diagram covering it have been reviewed and returned.
−### The utility interconnection application shall be filed at the earliest opportunity, because interconnection study and approval commonly take six to eighteen months and routinely govern the project schedule.
+### The module product data sheet is the document every other calculation reads from, and a substitution of module after the one-line diagram is reviewed changes the string voltage under 690.7, the circuit current under 690.8, the fuse rating under 690.9, the fire class rating under UL 2703, the attachment loads, and the energy model at once, which is why the module is released first and the rest follows it. {note}
−### The maximum PV system voltage submitted shall be the value calculated under NEC 690.7 using the lowest expected ambient temperature at the site, not the module nameplate open-circuit voltage at standard test conditions. {note}
+## Informational Submittals {toc}
+### The Contractor shall submit the following with or before the action submittals:
+
+- the qualifications of the module and inverter manufacturers, the installing contractor, the supervising installer, and the field testing firm, as Quality Assurance requires
+- the manufacturers' installation instructions for the modules, the inverters, the module-level electronics, the racking, and the connectors, including the torque values, the clamp zones, and the permitted module orientations
+- the written acceptance by the roofing manufacturer of the attachment or ballast system and its installation on the roof covering in place, where the array is on a roof, as the Installation article requires
+- the written confirmation from the structural engineer of record that the roof or the foundations carry the loads shown in the delegated mounting design, where that confirmation is not already in the contract documents
+- the utility correspondence on the interconnection application, including the IEEE 1547 categories, the export limit, the disconnect requirements, and the witness test requirements the utility has assigned
+- the commissioning plan, listing each test of IEC 62446-1 and of this standard, the instruments, the acceptance criteria, and the witnesses
+- the production guarantee instrument, where this standard requires one, with the model and the measurement method it is settled against
+
+```datasheet
+label: Informational Submittals
+type: checkbox
+options:
+ - "Manufacturer, installer, and testing firm qualifications"
+ - "Manufacturers' installation instructions"
+ - "Roofing manufacturer's acceptance of the attachment system"
+ - "Structural engineer of record confirmation of load capacity"
+ - "Utility interconnection correspondence"
+ - "Commissioning plan"
+ - "Production guarantee instrument"
+default:
+ - "Manufacturer, installer, and testing firm qualifications"
+ - "Manufacturers' installation instructions"
+ - "Roofing manufacturer's acceptance of the attachment system"
+ - "Structural engineer of record confirmation of load capacity"
+ - "Utility interconnection correspondence"
+ - "Commissioning plan"
+constraint: all_of
+```
+
## Closeout Submittals {toc}
−### The Contractor shall provide the following at substantial completion before the PV work is accepted:
+### The Contractor shall submit the following before the photovoltaic system is accepted:
−- As-built single-line diagram and site plan reflecting the installed system
−- Commissioning and acceptance test reports, including insulation resistance, polarity, open-circuit voltage, and operating current readings per circuit
−- The executed utility interconnection agreement and the utility witness-test or permission-to-operate documentation
−- Operation and maintenance data for modules, inverters, racking, and the monitoring system
−- The monitoring system access credentials and the revenue-grade meter commissioning record
−- Warranty documentation for modules, inverters, and racking
+- the record drawings, showing the array as built with the string assignment of every module, the serial numbers of the inverters and the module-level electronics by location, the routing of every circuit, the locations of every disconnect and the rapid shutdown initiator, and the point of interconnection
+- the commissioning report in the form IEC 62446-1 requires, with the result of every test in the commissioning plan, the current-voltage curves and the thermographic images where those tests are selected, and the correction of every failure
+- the inverter settings as left, including the IEEE 1547 category, the trip and ride-through settings, the grid-support function settings, and the export limit, with the password or access level that protects them
+- the utility's permission to operate and the executed interconnection agreement
+- the performance acceptance test report, where a performance test is selected under this standard
+- the operation and maintenance data for the modules, the inverters, the module-level electronics, the racking, the monitoring system, and the production meter, with the manufacturers' maintenance schedules for the warranty terms
+- the warranty certificates for the modules, the inverters, the module-level electronics, the racking, and the monitoring service, registered in the Owner's name, and the installation and production guarantee instruments
+- the administrator credentials for the monitoring platform and the inverter interfaces, transferred to the Owner
+- the record of the Owner training this standard requires
+- a signed receipt from the Owner for the spare parts delivered
```datasheet
−label: Required Closeout Submittals
+label: Closeout Submittals
type: checkbox
options:
− - "As-built single-line diagram and site plan"
− - "Commissioning and acceptance test reports"
− - "Executed interconnection agreement and permission to operate"
+ - "Record drawings with string assignments and serial numbers"
+ - "IEC 62446-1 commissioning report"
+ - "Inverter settings as left"
+ - "Permission to operate and interconnection agreement"
+ - "Performance acceptance test report"
- "Operation and maintenance data"
− - "Monitoring credentials and meter commissioning record"
− - "Warranty documentation"
−default: ["As-built single-line diagram and site plan", "Commissioning and acceptance test reports", "Executed interconnection agreement and permission to operate", "Operation and maintenance data", "Warranty documentation"]
+ - "Warranty, installation guarantee, and production guarantee documents"
+ - "Monitoring and inverter credentials transferred"
+ - "Owner training record"
+ - "Spare parts receipt"
+default:
+ - "Record drawings with string assignments and serial numbers"
+ - "IEC 62446-1 commissioning report"
+ - "Inverter settings as left"
+ - "Permission to operate and interconnection agreement"
+ - "Operation and maintenance data"
+ - "Warranty, installation guarantee, and production guarantee documents"
+ - "Monitoring and inverter credentials transferred"
+ - "Owner training record"
+ - "Spare parts receipt"
+constraint: all_of
```
+### The string assignment on the record drawings is the document a technician reads when one string reads low ten years on; without it, finding the module behind the fault means lifting modules until the current returns, and an array whose record drawing was never made is maintained by that method for its whole life. {note}
+
# Quality Assurance {toc}
−## Listing and Labeling {toc}
+## Listings {toc}
−### PV modules shall be listed and labeled to UL 61730 by a Nationally Recognized Testing Laboratory.
+### Modules shall be listed and labeled to UL 61730-1 and UL 61730-2 by a Nationally Recognized Testing Laboratory, and shall carry the IEC 61215 design qualification for the module type furnished.
−### PV modules already listed to UL 1703 may be used only where the listing remains valid and the AHJ accepts the legacy listing for the installation.
+### Inverters, module-level electronics, and interconnection system equipment shall be listed to UL 1741, and equipment that operates in parallel with the utility shall be listed to Supplement SB of UL 1741 as conforming to IEEE 1547 and tested to IEEE 1547.1, except where the serving utility requires Supplement SA in writing.
−### Inverters, converters, and interconnection system equipment shall be listed and labeled to UL 1741 with the supplement required by the serving utility.
+### Supplement SA aligns the inverter with the California Rule 21 functions and Supplement SB demonstrates conformance to IEEE 1547-2018; the two are not interchangeable, nearly every utility outside California and most inside it now require SB, and an inverter listed to the supplement the utility did not ask for is rejected at interconnection review after it is installed. {note}
−### Racking and mounting systems shall be listed and labeled to UL 2703.
+### The mounting system, including its clamps, its bonding components, and its ground lugs, shall be listed to UL 2703 with the module furnished, and the system fire class rating under UL 2703 shall be established with that module.
−### A listed PV hazard control system, where used to meet rapid shutdown, shall be listed and labeled to UL 3741.
+### A hazard control system furnished to satisfy rapid shutdown shall be listed to UL 3741 as the combination of module, module-level device where any, racking, wiring method, and inverter furnished, and a combination the listing does not cover shall not be accepted as a hazard control system.
−### Equipment that is not listed and labeled as required by this standard shall not be installed.
+### Photovoltaic wire shall be listed to UL 4703, connectors to UL 6703, photovoltaic fuses to UL 248-19, circuit breakers in DC photovoltaic circuits to UL 489B, arc-fault protection to UL 1699B, DC surge protective devices to UL 1449 for photovoltaic DC application, and a power control system that limits export to UL 3141.
+### No listed product shall be modified in the field in a manner that departs from the configuration under which it was listed.
+
+## Manufacturer Qualifications {toc}
+
+### The module manufacturer and the inverter manufacturer shall each have produced the product type furnished for not less than the period indicated in the datasheet and shall each maintain a warranty service organization in North America.
+
+```datasheet
+label: Manufacturer Production History
+type: range
+unit: years
+options:
+ min: 0
+ max: 20
+ setpoints: [0, 3, 5, 10, 20]
+default: 5
+constraint: min
+```
+
+### Five years is the period most projects require and the period the common module and inverter makers all clear, which is why it is the default; a longer period narrows the field to the longest-established makers, and a shorter one or none admits a new cell technology or a new inverter platform that no maker has shipped for long, at the risk that the warranty outlives the company. A module warranty is only as good as the company honoring it in year twenty, so the period is a proxy for that company still existing. {note}
+
+### The module manufacturer shall state in the qualification statement the factory at which the modules furnished are produced and shall furnish the flash test data of each module shipped, identified by serial number.
+
## Installer Qualifications {toc}
−### The PV system shall be installed under the supervision of personnel holding a recognized PV installation certification and experienced with systems of comparable size and topology.
+### The photovoltaic system shall be installed by the installer indicated in the datasheet.
−### The electrical interconnection shall be performed by a licensed electrician working under a licensed electrical contractor.
+```datasheet
+label: Installer Qualification
+type: radio
+options:
+ - "Licensed electrical contractor with a NABCEP PV Installation Professional supervising the work on site"
+ - "Licensed electrical contractor trained by the module, inverter, and racking manufacturers on the products furnished"
+ - "Licensed electrical contractor holding the state's photovoltaic or solar contractor license where one exists"
+```
−### A licensed structural engineer shall seal the roof and foundation load calculations, and for ground mounts a licensed geotechnical engineer shall provide the soils report. {note}
+### A NABCEP-certified supervisor is the qualification most Owners and incentive programs ask for and the one that proves photovoltaic competence independent of any product; manufacturer training proves competence on the products furnished and is the condition of most racking and inverter warranties; a state solar license is required in the states that issue one and proves nothing where none exists. Which is wanted depends on the state and on the program financing the system, so the field carries no default, and the three are often combined. {note}
−## Coordination {toc}
+### The electrical connections, the disconnects, the overcurrent devices, and the interconnection shall be made by electricians licensed in the jurisdiction working under a licensed electrical contractor.
−### The DC system voltage rating shall be locked at a single value across all DC-side components, including modules, conductors, connectors, combiners, disconnects, surge protective devices, and the inverter DC input.
+### Each person who works inside the array boundary on energized DC circuits shall be qualified under NFPA 70E for the DC voltage present and shall be trained in the manufacturer's procedure for opening connectors under load.
−### A mismatch in DC voltage rating among DC-side components is a common design defect; a 1000 V array assembled with a 600 V-rated connector or disconnect is non-compliant and unsafe. {note}
+### The field tests this standard names shall be performed by a firm qualified under [[sync/electrical-acceptance-testing]] or by the installing contractor's own technicians, as the Testing article of this standard indicates.
−### The arc-fault protection required by NEC 690.11 shall be verified compatible with the selected rapid-shutdown system and module-level electronics before procurement.
+## Delegated Design of the Mounting System {toc}
−### The 120% busbar allowance of NEC 705.12 shall be verified against the actual nameplate rating of the existing service and panelboard at the planned point of interconnection.
+### The mounting system shall be designed by an engineer licensed in the state of the project, engaged by the Contractor or the racking manufacturer, for the loads of [[parameter: adopted-building-code]] and ASCE/SEI 7 at the site, including the wind loads of ASCE/SEI 7 Chapter 29 for rooftop solar panels or Chapter 30 for a canopy, the snow load, the seismic loads of Chapter 13 for an attached or an unattached array for [[parameter: seismic-design-category]], and the dead load of the array.
−### Misapplying the NEC 705.12 120% rule to an existing panelboard with an undersized busbar is a frequent cause of interconnection rejection and a forced redesign of the connection point. {note}
+### The delegated design shall state the reaction delivered to the roof structure or the foundation at every attachment or ballast block, and shall be checked by the structural engineer of record against the capacity of the roof or the foundations before the array layout is released.
+### The racking engineer designs the racking for the loads and reports what the racking puts into the building; whether the building carries it is the structural engineer of record's determination, and nothing in this standard transfers that determination to the Contractor or the racking manufacturer. An array laid out before that determination is made is the most common source of a redesign, because a ballasted array on a roof framed for a light membrane load moves the ballast to the columns and the array off the roof. {note}
+
+### The delegated design shall use the edition of ASCE/SEI 7 the adopted building code references, and the wind design shall use the exposure and the roof zone coefficients for the roof geometry of the project, with the array edge, corner, and interior zones set as that edition defines them.
+
+## Regulatory and Utility Requirements {toc}
+
+### The Contractor shall confirm in writing with the Authority Having Jurisdiction, before the action submittals, the edition of NFPA 70 in force and the rapid shutdown, arc-fault, and surge protection provisions it applies to the project.
+
+### Article 690 changed in each of the 2017, 2020, and 2023 editions in the rapid shutdown method inside the array, the arc-fault threshold, the maximum voltage, and the wiring methods on a roof, and jurisdictions adopt editions years apart; the edition the Authority Having Jurisdiction enforces, not the latest published, decides the equipment, which is why it is confirmed before the design is submitted. {note}
+
+### The Contractor shall confirm in writing with the serving utility, before the action submittals, the interconnection path and study the system falls under, the IEEE 1547 categories and the export limit the utility assigns, the utility's requirements for a visible, lockable disconnect and for metering, and whether the utility witnesses the commissioning.
+
+### The photovoltaic system shall not be operated in parallel with the utility until the interconnection agreement is executed and the utility's permission to operate is in hand.
+
# Environmental and Service Conditions {toc}
−## The design ambient temperature range, snow load, and wind speed shall be the site-specific values from the building code and ASCE/SEI 7 for the project location. {note}
+## Enclosure Type {toc}
−### The maximum PV source-circuit voltage shall be calculated for the lowest expected ambient temperature at the site in accordance with NEC 690.7.
+### The enclosure type of the inverters, the combiners, the disconnects, and the junction and pull boxes of the photovoltaic system shall be as indicated in the datasheet.
−### The continuous-current ratings of conductors and overcurrent devices shall account for the elevated rooftop temperature and the irradiance and ambient temperature corrections of NEC 690.8.
+```datasheet
+label: Enclosure Type per NEMA 250
+type: select
+options:
+ - "Type 1"
+ - "Type 12"
+ - "Type 3R"
+ - "Type 4"
+ - "Type 4X"
+default: "Type 3R"
+```
−### The racking and attachments shall be designed for the site wind uplift and snow loads determined under ASCE/SEI 7 for the roof zone in which each module is located.
+### Photovoltaic equipment stands with the array, on a roof or in a field, and the inverters, combiners, and disconnects of most systems are outdoors, which is why the field departs from the indoor Type 1 convention and defaults to Type 3R; string inverters are built in Type 4 or Type 4X enclosures as the manufacturer's standard and exceed the default without a change in product. Type 1 and Type 12 are the ratings of an inverter installed in an electrical room, with Type 12 for a dusty industrial room; Type 4 is gasketed against hose-directed water and wind-driven rain and is the rating of an exposed rooftop or coastal site; Type 4X adds corrosion resistance for salt air, de-icing chemical, or a chemical atmosphere. {note}
+### Enclosures shall comply with UL 50E and NEMA 250 for the type selected, and the type shall be marked on the enclosure.
+
+### Equipment installed outdoors, on a roof, or under a carport shall have an enclosure of Type 3R, Type 4, or Type 4X.
+
+### Equipment installed where the atmosphere carries salt, de-icing chemical, chemical vapor, or another corrosive agent, including a site within one mile of a saltwater coast, shall have a Type 4X enclosure.
+
+### Where the enclosure type these clauses require exceeds the datasheet selection at an installed location, the higher type shall be furnished at that location and the conflict reported to the Engineer of Record before procurement.
+
+### Raceway entries into a Type 3R, Type 4, or Type 4X enclosure shall be made only with fittings listed to maintain the enclosure type and only at the entry locations the manufacturer provides, and entries into the top of an outdoor enclosure shall be avoided where the manufacturer provides another location.
+
+## Temperature and Altitude {toc}
+
+### Inverters and module-level electronics installed outdoors, on a roof, or in an unconditioned space shall deliver their rated continuous output at [[parameter: site-ambient-temperature-maximum]], and where the manufacturer reduces the output above a stated ambient temperature, the output at the site maximum shall be stated in the product data and shall be the rating used in the energy model.
+
+### Inverters shall be derated for [[parameter: altitude]] in accordance with the manufacturer's published correction factors where the altitude exceeds the rating basis of the listing, and the derated ratings shall be stated in the product data.
+
+### Modules, module-level electronics, connectors, and photovoltaic wire shall be rated for continuous operation from [[parameter: site-ambient-temperature-minimum]] to the cell and conductor temperatures reached in full sun at [[parameter: site-ambient-temperature-maximum]], and conductor ampacity on a roof shall include the temperature adder of NFPA 70 310.15 for the distance of the raceway above the roof where the adopted edition requires it.
+
+### A string inverter mounted on a roof in direct sun runs well above the air temperature, and a module in still air in full sun runs 25 °C to 35 °C above it, so the equipment is judged at the site maximum rather than at a nominal indoor value, and an inverter that derates at 45 °C delivers less than its nameplate through every summer afternoon the energy model counts on. {note}
+
+## Structural Loads at the Site {toc}
+
+### The mounting system shall be designed for the ultimate wind speed, the ground snow load, the exposure category, and the risk category stated on [[drawing: the structural general notes]], and where the structural drawings state none, for the values of the adopted building code at the site.
+
+### A ballasted or an attached rooftop array shall be installed only where the structural drawings or the structural engineer of record's written confirmation show the roof framing designed for the array dead load, the ballast, the concentrated loads at the attachments, and the drifted snow the array causes.
+
+### Where [[parameter: wind-borne-debris-region]] places the site in a wind-borne debris region, modules shall carry the mechanical load ratings the delegated design requires for the design wind pressure at the array location, and the clamp zones used shall be those under which the module's load rating was established.
+
+# System Configuration {toc}
+
+## System Function {toc}
+
+### The function of the photovoltaic system shall be as indicated in the datasheet.
+
```datasheet
−label: Design Wind Speed (Ultimate)
−type: range
−unit: mph
−min: 90
−max: 200
−step: 5
−default: 115
+label: System Function
+type: radio
+options:
+ - "Utility-interactive, ceasing to energize on loss of the utility"
+ - "Multimode, with storage under the energy storage standard, serving designated loads in an island"
+default: "Utility-interactive, ceasing to energize on loss of the utility"
```
+### A utility-interactive system produces only while the utility is present and is the system of the large majority of commercial projects, which is why it is the default; a multimode system pairs the array with storage that forms an island when the utility fails, which puts the storage, the islanding device, and the island loads under [[sync/battery-energy-storage-systems]] and leaves the array, its inverter or its DC coupling, and its rapid shutdown here. {note}
+
+### Where the system is multimode, the coupling of the array to the storage, the anti-islanding coordination between the generation inverter and the storage inverter, and the island loads shall be as [[sync/battery-energy-storage-systems]] requires, and the array DC circuits, their overcurrent protection, and their rapid shutdown shall comply with this standard.
+
+## Maximum DC Voltage {toc}
+
+### The maximum photovoltaic system DC voltage shall be as indicated in the datasheet, and every module, conductor, connector, combiner, fuse, disconnect, surge protective device, and inverter input in the DC circuits shall be rated for not less than that voltage.
+
```datasheet
−label: Ground Snow Load
+label: Maximum DC System Voltage
type: range
−unit: psf
−min: 0
−max: 100
−step: 5
−default: 20
+unit: V
+options:
+ min: 600
+ max: 1500
+ setpoints: [600, 1000, 1500]
+default: 1000
+constraint: exact
```
+### A 1000 V system is the design of nearly every array on a commercial roof, because NFPA 70 690.7 limits DC circuits on or in a building other than a dwelling to 1000 V and the string, central, and optimizer products are built for it, which is why it is the default; 600 V is the limit on a dwelling and the design of older and of microinverter and AC-module arrays, where the DC never leaves the module; 1500 V is permitted only for an array not on or in a building and is the design of ground-mount and canopy arrays large enough to justify the longer strings, the smaller conductors, and the 1500 V equipment that goes with them. {note}
+
+### DC circuits on or in a building shall not exceed 1000 V, and a system rated 1500 V shall be installed only where the array is not located on or in a building, in accordance with NFPA 70 690.7.
+
+### The maximum voltage of each source circuit shall be calculated under NFPA 70 690.7 with [[parameter: site-ambient-temperature-minimum]] as the lowest expected ambient temperature, by the method indicated in the datasheet, and shall not exceed the maximum system voltage or the lowest voltage rating of any component in the circuit.
+
```datasheet
−label: Lowest Expected Ambient Temperature (for NEC 690.7 voltage)
−type: range
−unit: °C
−min: -40
−max: 10
−step: 1
−default: -20
+label: Maximum Voltage Calculation Method
+type: radio
+options:
+ - "Open-circuit voltage corrected by the module manufacturer's temperature coefficient"
+ - "Open-circuit voltage corrected by the NFPA 70 Table 690.7(A) factor for crystalline modules"
+ - "Industry-standard method under engineering supervision, for systems of 100 kW and larger"
+default: "Open-circuit voltage corrected by the module manufacturer's temperature coefficient"
```
−### Modules and exposed equipment shall be rated for outdoor ultraviolet exposure and the full site temperature range over the system service life.
+### The manufacturer's coefficient is the method the module data sheet supports directly and the one nearly every design uses, which is why it is the default; the table factor is permitted for crystalline and multicrystalline modules where the coefficient is not available and is more conservative; the engineering-supervision method uses a statistical minimum temperature rather than the extreme and is permitted for systems of 100 kW and larger, where it adds a module or two to each string at the cost of a sealed calculation. {note}
−## Bifacial modules, where used, gain rear-side production from reflected irradiance; their source-circuit current rating shall include the bifacial gain so that conductors and overcurrent devices are not undersized.
+### A string one module too long is the defect the calculation exists to catch: the voltage is checked at standard test conditions and passes, the first cold clear morning after commissioning drives the open-circuit voltage past the inverter's input rating, and the inverter either refuses to start or is damaged, with the manufacturer's warranty excluding overvoltage. {note}
−# PV Modules {toc}
+## Power Conversion Architecture {toc}
−## Module Type and Rating {toc}
+### The power conversion architecture of the system shall be as indicated in the datasheet.
−### PV modules shall be new, of a single make and model within each array, and listed to UL 61730.
+```datasheet
+label: Power Conversion Architecture
+type: select
+options:
+ - "String inverters"
+ - "String inverters with DC optimizers at the modules"
+ - "Microinverters at the modules"
+ - "Central inverter"
+default: "String inverters"
+```
−### The module cell technology, nameplate power, and bifaciality shall be as scheduled below.
+### String inverters convert the output of a group of strings at the roof or the ground, carry the lowest cost per watt at commercial scale, are replaced one at a time without a crane, and are the architecture of most commercial arrays, which is why the field defaults to them, with rapid shutdown inside the array met by module-level shutdown devices or a hazard control system; DC optimizers add a converter at each module that tracks that module's maximum power point, reports per-module data, and performs the module-level shutdown, which recovers the output of an array with partial shade, several orientations, or mismatched modules at the cost of a device per module and a dependence on the inverter maker that lists with it; microinverters convert at each module, carry no DC beyond the module, meet rapid shutdown inherently, and are replaced module by module, at the highest cost per watt and with the most devices on the roof, which suits a small or a heavily shaded array; a central inverter converts a whole array of several hundred kilowatts or more in one enclosure on a pad, at the lowest cost per watt at that scale and with a single point of failure that takes the whole array down, which suits a large ground mount or canopy. {note}
+### Where DC optimizers or microinverters are selected, the module-level device shall be listed with the inverter or the gateway it communicates with as one system, and a module-level device of one maker shall not be combined with the inverter of another unless the combination is listed.
+
+### Where a central inverter is selected, it shall be set on a pad constructed under [[sync/concrete-pads]] or in an electrical room with the working space NFPA 70 110.26 requires for its voltage, and the DC combiners and recombiners feeding it shall be furnished under this standard.
+
+# Modules {toc}
+
+## Cell Technology {toc}
+
+### The cell technology of the modules shall be as indicated in the datasheet, and every module in an array shall be of one manufacturer, one model, and one power class.
+
```datasheet
label: Module Cell Technology
type: select
options:
− - "Monocrystalline PERC"
− - "Monocrystalline TOPCon"
− - "Monocrystalline heterojunction (HJT)"
−default: "Monocrystalline TOPCon"
+ - "Monocrystalline silicon, tunnel oxide passivated contact (TOPCon)"
+ - "Monocrystalline silicon, passivated emitter and rear cell (PERC)"
+ - "Monocrystalline silicon, heterojunction (HJT)"
+ - "Monocrystalline silicon, back contact"
+ - "Thin film, cadmium telluride"
+default: "Monocrystalline silicon, tunnel oxide passivated contact (TOPCon)"
```
+### Tunnel oxide passivated contact cells are the large majority of modules shipped since the industry moved off PERC, with efficiencies in the low to mid twenties, a lower temperature coefficient than PERC, and a bifacial construction as standard, which is why the field defaults to them; PERC modules are the previous generation, still produced, a point or two lower in efficiency and warmer in their coefficient, at the lowest price where stock remains; heterojunction cells carry the lowest temperature coefficient and the highest bifaciality of the silicon technologies and cost more, which pays on a hot site or a high-albedo ground mount; back-contact cells move the contacts to the rear and reach the highest efficiencies in a given frame, at a premium, which pays where the roof area is the constraint; cadmium telluride thin film carries a low temperature coefficient and a low embodied energy, is produced by few makers, is built in a frameless glass-glass form with its own racking, and is the choice of a large ground mount that buys on domestic content or on hot-climate yield rather than on efficiency per square foot. {note}
+
+### The module power tolerance shall be positive only, and the flash-test power of each module shipped shall be not less than its nameplate power.
+
+### Modules shall have passed the potential-induced degradation test of IEC TS 62804-1 at the maximum system voltage selected under this standard with a power loss not exceeding 5 percent, and the manufacturer shall state the result in the product data.
+
+### Modules of a given technology lose power when the array voltage drives ions through the encapsulant toward the cells, and the loss is largest at 1000 V and 1500 V on a hot humid site and on the modules at the negative end of a string; the test demonstrates that the module furnished resists it, and a module that was never tested cannot be shown to. {note}
+
+## Module Construction {toc}
+
+### The construction of the modules shall be as indicated in the datasheet.
+
```datasheet
−label: Module Configuration
+label: Module Construction
type: radio
options:
− - "Monofacial"
− - "Bifacial (glass-glass)"
−default: "Monofacial"
+ - "Glass front, polymer backsheet, monofacial"
+ - "Glass front, glass rear, bifacial"
+ - "Glass front, glass rear, monofacial"
```
−```datasheet
−label: Module Nameplate Power (STC)
−type: range
−unit: W
−min: 350
−max: 700
−step: 5
−default: 550
−```
+### A polymer backsheet is the lighter and lower-cost construction and is what a roof whose load capacity is the constraint is specified with, and it is the construction whose backsheets have cracked in the field on some product lines after a decade; a glass-glass bifacial module collects the light reflected from the roof or the ground onto its rear face, which adds from a few percent on a dark membrane to twenty percent or more on a white roof or a high-albedo ground mount, carries a longer performance warranty on most product lines, and weighs more; a glass-glass monofacial module has the rear glass without the bifacial cell and is bought for the durability alone. The construction follows the roof capacity and the albedo, so the field carries no default. {note}
+### Where bifacial modules are selected, the short-circuit current used in the NFPA 70 690.8 calculations shall include the rear-side gain the manufacturer publishes for the mounting height, the row spacing, and the albedo of the installation, and the inverter maximum input current shall be checked against the same value.
+
+### The frame of the modules shall be as indicated in the datasheet.
+
```datasheet
label: Module Frame
type: radio
options:
− - "Anodized aluminum framed"
− - "Frameless (glass-glass)"
−default: "Anodized aluminum framed"
+ - "Anodized aluminum frame"
+ - "Frameless"
+default: "Anodized aluminum frame"
```
−### Each module shall bear a permanent nameplate stating the open-circuit voltage, short-circuit current, maximum power voltage and current, maximum power, maximum system voltage, and maximum series fuse rating.
+### A framed module is clamped or bolted by its frame, bonds through the frame to the UL 2703 racking, and is the construction of nearly every module on the market, which is why the field defaults to it; a frameless module is held by edge clamps bearing on the glass, is bonded only where a rail or clamp is listed to bond it, and is the construction of the cadmium telluride product and of a few glass-glass silicon lines, and it is installed only with the racking listed for it. {note}
−### Modules within a single source circuit shall be electrically matched so that current mismatch does not impair string performance.
+## Module Power Rating {toc}
−## Module Performance Basis {toc}
+### The nameplate power of the modules at standard test conditions shall be as indicated in the datasheet.
−### Modules should additionally be qualified to IEC 61215 for design qualification and type approval as a performance basis in addition to the UL listing.
+```datasheet
+label: Module Nameplate Power at Standard Test Conditions
+type: range
+unit: W
+drawing_ref: "the photovoltaic equipment schedule"
+options:
+ min: 300
+ max: 800
+ step: 5
+default: deferred
+constraint: min
+```
−### The module power temperature coefficient and the rated power tolerance shall be documented so the array energy model reflects field operating temperatures rather than standard test conditions.
+### The module power is the product of the technology, the cell count, and the format the manufacturer builds, and with the module count on the drawings it sets the array size, so the value is read from the photovoltaic equipment schedule; a module of higher power in the same frame dimensions is accepted against the schedule value, and one in a larger frame changes the layout and the attachment loads and is a substitution. {note}
−# Inverters {toc}
+### Each module shall bear the nameplate NFPA 70 690.51 requires, stating the open-circuit voltage, the short-circuit current, the maximum power voltage and current, the maximum power, the maximum system voltage, and the maximum series fuse rating.
−## Inverter Topology {toc}
+## Fire Classification {toc}
−### The inverter topology shall be one of the configurations scheduled below, selected to suit the array layout, the shading conditions, and the rapid-shutdown and monitoring requirements.
+### The system fire class rating of the modules with the mounting system under UL 2703 shall be as indicated in the datasheet.
```datasheet
−label: Inverter Topology
+label: System Fire Class Rating
type: select
+derived: "the roof covering fire classification that [[parameter: adopted-building-code]] requires for the roof the array is installed on"
options:
− - "String inverter"
− - "String inverter with DC optimizers (MLPE)"
− - "Microinverter (AC modules)"
− - "Central / skid-mounted inverter"
−default: "String inverter"
+ - "Class A"
+ - "Class B"
+ - "Class C"
+default: derived
```
−### Inverters shall be listed to UL 1741 with the supplement required by the serving utility and shall comply with IEEE 1547-2018 where Supplement SB applies.
+### The building code requires a rooftop array to carry the fire classification it requires of the roof covering beneath it, and the classification is established for the module and the racking together under UL 2703, because the gap between the module and the roof changes how a fire spreads under the array; a module's own fire type under UL 61730 is one input to that system rating and is not the rating itself. The roof classification is set by the construction type and the occupancy, which is why the field is derived from it. {note}
−### Inverters shall provide the grid-support, ride-through, and anti-islanding functions of IEEE 1547-2018 as configured for the utility interconnection agreement.
+### A rooftop array shall carry a system fire class rating not lower than the roof covering classification the adopted building code requires for the building, established by the UL 2703 listing of the racking with the module furnished and the module's fire type under UL 61730.
−### The inverter anti-islanding function shall cease energizing the utility upon loss of the utility source so that no PV power is exported to a de-energized utility conductor.
+# Inverters {toc}
−## Inverter Ratings {toc}
+## Interconnection Functions {toc}
−### The maximum DC input voltage of the inverter shall be greater than the maximum PV source-circuit voltage calculated under NEC 690.7.
+### The IEEE 1547 normal performance category of the inverters shall be as indicated in the datasheet.
−### The DC-to-AC sizing ratio of the array to the inverter shall be documented and shall not cause sustained inverter clipping beyond the value assumed in the energy model.
+```datasheet
+label: IEEE 1547 Normal Performance Category
+type: radio
+drawing_ref: "the utility interconnection agreement"
+options:
+ - "Category A"
+ - "Category B"
+default: deferred
+```
+### The IEEE 1547 abnormal performance category of the inverters shall be as indicated in the datasheet.
+
```datasheet
−label: Maximum DC System Voltage
+label: IEEE 1547 Abnormal Performance Category
type: radio
−unit: V
+drawing_ref: "the utility interconnection agreement"
options:
− - "600"
− - "1000"
−default: "1000"
+ - "Category I"
+ - "Category II"
+ - "Category III"
+default: deferred
```
+### The serving utility assigns both categories in the interconnection agreement and the inverters are set to them, which is why both fields are deferred to that document. Normal Category A requires the minimum reactive power capability; Category B requires more and the volt-var and volt-watt functions, and most utilities now assign it to photovoltaic inverters. Abnormal Category I rides through the least disturbance, Category II rides through the disturbances a bulk-system event imposes, and Category III rides through the most and is assigned on circuits with a high penetration of distributed resources, where the utility wants every inverter to stay connected through a fault elsewhere. {note}
+
+### The inverters shall provide the constant power factor, voltage-reactive power, active power-reactive power, voltage-active power, and frequency-droop functions of IEEE 1547, each settable in the field, and shall be set to the values of the interconnection agreement, recorded in the settings as left, and protected from change by a password or a utility-controlled access level.
+
+### The anti-islanding protection shall detect the loss of the utility and cease to energize the utility side within the time IEEE 1547 requires, by a method stated in the product data, and the inverters shall not reconnect until the utility has returned within the IEEE 1547 enter-service criteria for the time the serving utility requires.
+
+### The export of power from the photovoltaic system to the utility shall be as indicated in the datasheet.
+
```datasheet
−label: Inverter AC Output Configuration
+label: Export to the Utility
+type: radio
+drawing_ref: "the utility interconnection agreement"
+options:
+ - "Export permitted up to the limit in the interconnection agreement"
+ - "Limited export enforced by a power control system listed to UL 3141"
+ - "No export, enforced by a power control system listed to UL 3141 or a reverse-power relay"
+default: deferred
+```
+
+### Whether the array is allowed to push power past the service point is the utility's decision in the interconnection agreement, which is why the field is deferred to it. A system permitted to export sells its surplus under net metering or a tariff and needs the full interconnection review; a limited-export system is held below the circuit's hosting capacity and often clears a shorter review; a non-export system is interconnected under the simplest review and is the arrangement where the utility will not accept generation on the circuit or where the array is sized to the daytime load. The power control system that enforces a limit is listed to UL 3141 and recognized by NFPA 70 705.13, and it is also one of the devices 705.12 recognizes for satisfying the bus limits at a load-side interconnection. {note}
+
+### Where limited or no export is selected, the power control system shall measure the power at the service point or at the point the interconnection agreement names, shall hold the export at or below the limit within the time its listing states, and shall reduce the inverter output to zero on loss of the measurement.
+
+## AC Output {toc}
+
+### The AC output voltage and phase of the inverters at the point of interconnection shall be as indicated in the datasheet.
+
+```datasheet
+label: Inverter AC Output Voltage and Phase
type: select
+drawing_ref: "the photovoltaic one-line diagram"
options:
− - "208Y/120 V, 3-phase"
− - "480Y/277 V, 3-phase"
− - "240/120 V, split-phase"
− - "480 V, 3-phase delta"
−default: "480Y/277 V, 3-phase"
+ - "240/120 V, 1Φ"
+ - "208Y/120 V, 3Φ"
+ - "480Y/277 V, 3Φ"
+ - "600Y/347 V, 3Φ"
+ - "Medium voltage, through a step-up transformer"
+default: deferred
```
+### The inverter output matches the bus it lands on, which the one-line diagram fixes, and where the array is large relative to a 208 V service the inverters are furnished at 480 V and a step-down transformer is placed between them and the bus, or the array is interconnected at medium voltage through its own transformer; the transformer in either case is furnished under its own standard and the loss it adds is carried in the energy model. {note}
+
+### The inverters shall deliver their rated output at the power factor the interconnection agreement requires at the point of interconnection, and the harmonic current they inject shall comply with IEEE 1547 and with IEEE 519 at the point of common coupling.
+
+### The weighted efficiency of the inverters shall be not less than the value indicated in the datasheet.
+
```datasheet
−label: Module-Level Power Electronics (MLPE)
+label: Inverter Weighted Efficiency
+type: range
+unit: '%'
+options:
+ min: 94
+ max: 99.5
+ step: 0.5
+constraint: min
+```
+
+### The weighted efficiency is the California Energy Commission figure the inverter listing publishes, averaged over the loading profile an array actually runs at, and it is the figure the energy model uses; transformerless string inverters publish in the upper nineties, central inverters at the top of that range, and microinverters a point or two lower. The value follows the architecture selected, so the field carries no default. {note}
+
+### The ratio of the array nameplate DC power to the inverter rated AC power shall not exceed the value indicated in the datasheet.
+
+```datasheet
+label: DC-to-AC Ratio
+type: range
+unit: ratio
+options:
+ min: 1.0
+ max: 1.6
+ step: 0.05
+constraint: max
+```
+
+### An array larger than its inverter clips its output at midday on clear days and gains more energy in the mornings, the afternoons, and the cloudy months than it loses at noon, up to a ratio the energy model finds and the inverter's maximum input current permits; ratios between 1.2 and 1.35 are where most commercial designs land, a ratio near 1.0 suits a utility that limits AC capacity tightly against DC, and a higher ratio suits an array paired with storage that recovers the clipped energy. The value is an energy-model result, so the field carries no default. {note}
+
+### The inverter maximum DC input current, the maximum input voltage, and the maximum power point tracking window shall be matched to the source circuits connected to it, with the voltage at [[parameter: site-ambient-temperature-minimum]] below the maximum input and the voltage at the maximum cell temperature above the tracking minimum.
+
+## Ground-Fault and Arc-Fault Protection {toc}
+
+### The photovoltaic system shall be provided with DC ground-fault protection in accordance with NFPA 70 690.41, integral to the inverter or by a separate listed device, and the protection shall detect the fault, interrupt the faulted circuit or the inverter output, and indicate the fault at the inverter and through the monitoring system.
+
+### Where a non-isolated inverter is furnished, the manufacturer shall state in the product data how the inverter detects a ground fault and an insulation deterioration on the array and how it limits DC injection into the AC system.
+
+### DC circuits operating at 80 V or more between any two conductors shall be protected by a listed photovoltaic arc-fault circuit interrupter or by inverter-integral arc-fault protection listed to UL 1699B, in accordance with NFPA 70 690.11, and the protection shall be verified compatible with the module-level electronics and the rapid shutdown devices furnished.
+
+### Arc-fault detection reads a signature in the DC current, and a module-level device, a long home run, or a combiner of another maker can mask that signature or mimic it; the compatibility of the detector with everything on the DC side is a listing question the inverter maker answers in writing, and a system assembled from parts whose makers never tested them together trips on nuisance arcs or misses the real one. {note}
+
+# Rapid Shutdown {toc}
+
+## Rapid Shutdown Method {toc}
+
+### The photovoltaic system installed on or in a building shall include a rapid shutdown function in accordance with NFPA 70 690.12 for the adopted edition, and the method of controlling the conductors inside the array boundary shall be as indicated in the datasheet.
+
+```datasheet
+label: Rapid Shutdown Method Inside the Array Boundary
type: radio
options:
− - "None (string only)"
− - "DC optimizers"
− - "Microinverters"
−default: "None (string only)"
+ - "Module-level shutdown devices or module-level power electronics"
+ - "Photovoltaic hazard control system listed to UL 3741"
+ - "Rapid shutdown not required, array not on or in a building"
```
−### Transformerless (non-isolated) inverters shall provide the DC ground-fault detection and interruption required by NEC 690.41 integral to the inverter.
+### Module-level devices open or short each module or each pair of modules when the initiator operates, bring every conductor in the array to the limit within the time, work with any racking and any wiring method, and add a device per module or per two modules that communicates with or is powered by the inverter; a hazard control system listed to UL 3741 reaches the same level of protection for a firefighter by the construction of the array itself, with the specific modules, racking, wiring, and inverter tested as a combination, and it removes the module-level devices at the cost of being bound to that listed combination for the life of the system and to the few combinations listed; an array that is not on or in a building, as a ground mount or a detached canopy, is outside 690.12 and needs neither. The method follows the architecture and the mounting selected, so the field carries no default. {note}
−### Where a non-isolated inverter does not provide integral ground-fault protection, a separate listed ground-fault protection device shall be furnished.
+### Conductors leaving the array boundary shall be reduced to not more than 30 V within 30 seconds of rapid shutdown initiation, and conductors inside the array boundary shall be reduced to not more than 80 V within 30 seconds where module-level devices or electronics are furnished, in accordance with NFPA 70 690.12.
−# Rapid Shutdown and Arc-Fault Protection {toc}
+### Where a hazard control system is furnished, the modules, the module-level devices where any, the racking, the wiring method, and the inverter shall be the combination the UL 3741 listing names, and no component of the combination shall be substituted without a listing that covers the substitute.
−## Rapid Shutdown {toc}
+### The array boundary shall be as NFPA 70 690.12 defines it for the adopted edition, shall be shown on the array layout plan, and the rapid shutdown label shall be placed and worded as the Identification article requires.
−### The PV system shall include a rapid-shutdown function meeting NEC 690.12 for the adopted code edition.
+## Rapid Shutdown Initiation {toc}
−### The rapid-shutdown method shall be one of the approaches scheduled below.
+### The rapid shutdown initiation device shall be as indicated in the datasheet.
```datasheet
−label: Rapid-Shutdown Method
+label: Rapid Shutdown Initiation Device
type: radio
options:
− - "Module-level shutdown (≤1 V within array boundary, 30 s)"
− - "Listed PV hazard control system per UL 3741 (≤80 V at array boundary, 30 s)"
−default: "Module-level shutdown (≤1 V within array boundary, 30 s)"
+ - "The service disconnecting means"
+ - "The photovoltaic system disconnecting means"
+ - "A dedicated rapid shutdown switch at a readily accessible outdoor location"
```
−### Module-level rapid shutdown shall reduce controlled conductors within the array boundary to not more than 1 V within 30 seconds of initiation.
+### Initiating from the service disconnect lets the fire department shut down the array with the same switch that kills the building and is the arrangement most fire departments ask for on a building with one service; initiating from the photovoltaic system disconnect works where that disconnect is outdoors and readily accessible, and fails where it is in an electrical room; a dedicated switch at the exterior near the fire department connection gives responders one marked device whatever the service arrangement and is required by some jurisdictions. The device follows the service arrangement and the fire department's preference, so the field carries no default. {note}
−### A listed PV hazard control system per UL 3741, where used, shall reduce conductors leaving the array boundary to not more than 80 V within 30 seconds and shall satisfy the within-boundary hazard reduction as a listed system.
+### The initiation device shall be readily accessible, shall be located outside the building or at the service equipment, shall not be inside a locked room or behind a locked gate the fire department cannot open, and shall initiate rapid shutdown of every photovoltaic system on the building when operated.
−### Where a listed PV hazard control system is selected, its availability for the specific inverter and racking combination shall be confirmed before procurement, because the listed-system market is still maturing and not all combinations are listed together.
+### Where more than one initiation device serves a building, operation of any one shall initiate rapid shutdown of every system, and the devices shall be marked as the Identification article requires.
−### A rapid-shutdown initiation device shall be provided at a location accessible to first responders.
+### The rapid shutdown function shall operate on loss of AC power to the inverter whether or not the initiation device is operated, so that an inverter that loses the utility brings the array conductors to the limit without a person at the switch.
−### The rapid-shutdown initiator shall be marked with the label required by NEC 690.56(C).
+# DC Circuits, Combiners, and Disconnects {toc}
−### The rapid-shutdown initiator shall not be located inside a locked room or otherwise inaccessible space; an initiator that responders cannot reach is a frequent plan-review rejection.
+## Source and Output Circuit Conductors {toc}
+### Single-conductor cable exposed outdoors within the array shall be of the type indicated in the datasheet, and the home runs and the output circuits beyond the array shall be building wire and raceway under [[sync/conductors-and-cables]] and [[sync/raceways-and-conduit]].
+
```datasheet
−label: Rapid-Shutdown Initiator Location
−type: select
+label: Exposed Single-Conductor Cable Within the Array
+type: radio
options:
− - "At the main service disconnect / utility meter"
− - "At a dedicated exterior firefighter switch"
− - "At the inverter where accessible from grade"
−default: "At the main service disconnect / utility meter"
+ - "Photovoltaic wire listed to UL 4703"
+ - "USE-2 listed to UL 854"
+default: "Photovoltaic wire listed to UL 4703"
```
−## Arc-Fault Protection {toc}
+### Photovoltaic wire is the cable the modules themselves are fitted with, is rated 1000 V or 1500 V, sunlight-resistant, wet-rated, flexible, and permitted by NFPA 70 690.31 for every exposed single-conductor application within the array including an ungrounded array, which is why the field defaults to it; USE-2 is permitted for the same exposed runs on a functionally grounded array and costs less in the larger sizes, and it is rated 600 V, which limits it to a 600 V system. {note}
−### PV DC source and output circuits shall be provided with arc-fault protection meeting NEC 690.11.
+### Source circuit conductors shall be sized to the currents of NFPA 70 690.8 with the short-circuit current multiplied by 125 percent for the maximum circuit current, or determined under engineering supervision for a system of 100 kW and larger as 690.8 permits, and with the conductor ampacity corrected for the rooftop temperature, the conduit fill, and the continuous duty of 690.8(B).
−### The arc-fault protection function shall be verified to operate correctly with the selected module-level electronics and rapid-shutdown system.
+### DC circuits inside a building shall be installed in a metal raceway, in Type MC cable listed for the purpose, or in a metal enclosure from the point of penetration to the first readily accessible disconnecting means, in accordance with the provisions of NFPA 70 690.31 for DC circuits on or in a building, and shall be marked as the Identification article requires.
−# Conductors, Connectors, and Overcurrent Protection {toc}
+### Exposed cable within the array shall be supported and secured at intervals not exceeding those the cable listing and NFPA 70 690.31 permit, shall be kept off the roof surface and out of standing water, shall be protected from the module edges and the racking by clips or sleeves listed for the purpose, and shall not be secured with ties that degrade in sunlight.
−## DC Circuits {toc}
+### Cable lying on a roof membrane is the most common finding of a five-year inspection: the ties have failed, the cable has abraded on the module frames, and the insulation at the low points has been under water every winter, and an insulation fault that the ground-fault detector then finds is traced to a cable tie that cost a cent. {note}
−### PV source-circuit and output-circuit conductors shall be sized to the corrected continuous current of NEC 690.8 and the conductor ampacity rules of NEC Article 690 and Article 310.
+## Connectors {toc}
−### Exposed single-conductor DC PV wire shall be listed PV wire or photovoltaic cable suitable for wet locations and sunlight resistance.
+### Connectors in the DC circuits shall be listed to UL 6703, rated for the maximum system voltage and the circuit current, of a locking type requiring a tool to open where readily accessible, and the mating halves of each connection shall be of the same manufacturer and series unless the combination is listed as intermateable, in accordance with NFPA 70 690.33.
−### DC connectors shall be listed, of a single type within a connection, and shall not be mated to connectors of a different make or series.
+### Connectors of different makers engage mechanically and fail electrically; a mismatched pair that heats, arcs, and melts is the leading cause of fire in a photovoltaic array, and the connector on the module lead sets the series for every field-installed connector, which is why the module connector series is stated in the product data and the field connectors and the crimp tool are bought to it. {note}
−### Mating DC connectors of different makes or series is a known fire and failure hazard even where the connectors physically engage; intermateability shall be confirmed by listing, not by fit.
+### Field-installed connectors shall be assembled with the crimp tool and the die the connector manufacturer specifies for the conductor furnished, and the installer shall verify each crimp by the pull or inspection method the manufacturer's instructions state.
−### Overcurrent devices protecting PV source and output circuits shall be listed for DC PV use and rated for the maximum circuit voltage and the available fault current.
+## Combiners and Overcurrent Protection {toc}
−### The conductors and raceways shall be coordinated with [[sync/conductors-and-cables]] and [[sync/raceways-and-conduit]], and the DC home-run routing shown on the drawings [[drawing: DC home-run routing]].
+### The source circuits shall be combined by the provision indicated in the datasheet.
−## AC Circuits {toc}
+```datasheet
+label: Source Circuit Combining Provision
+type: radio
+options:
+ - "Fused combiner boxes located at the array"
+ - "Fuse holders integral to the inverter DC input"
+ - "Wiring harnesses with in-line fuses at the array"
+```
−### Inverter output (AC) circuits shall be sized to 125% of the continuous inverter output current.
+### A combiner box at the array collects the strings of a block, carries a fuse for each, a disconnect where the design calls for one, and the DC surge protective device, and reduces the home runs to one output circuit, which suits a central inverter or a string inverter far from its strings; fuse holders in the inverter input are the arrangement of most string-inverter arrays, where each string runs to the inverter and the inverter holds the fuses, so that no combiner stands on the roof; in-line fused harnesses are factory-made assemblies that combine strings at the racking and suit a large ground mount with trackers, where they save the labor of a combiner at each row. The provision follows the architecture and the distance from the strings to the inverter, so the field carries no default. {note}
−### The AC overcurrent device serving the inverter output shall be rated for the inverter maximum output current and the available fault current at the point of connection.
+### Overcurrent devices in DC photovoltaic circuits shall be furnished where NFPA 70 690.9 requires them, shall be photovoltaic fuses listed to UL 248-19 or circuit breakers listed to UL 489B, rated for the maximum system voltage and for not less than 125 percent of the maximum circuit current, and shall not exceed the maximum series fuse rating of the module.
−### The point of interconnection shall be shown on the drawings [[drawing: interconnection point]].
+### Where the sum of the short-circuit currents of the parallel source circuits that can backfeed a circuit does not exceed the ampacity of its conductors and the maximum series fuse rating of its modules, overcurrent protection of that circuit is not required by 690.9, and the calculation that shows it shall be included in the action submittals.
−# Grounding and Bonding {toc}
+### Combiner boxes shall be listed, shall carry the enclosure type the Environmental and Service Conditions article requires for their location, shall have touch-safe fuse holders rated for the fuse furnished, and shall be furnished with a DC disconnecting means where the one-line diagram shows one at the combiner.
−## Equipment Grounding {toc}
+## DC Disconnecting Means {toc}
−### Exposed non-current-carrying metal parts of modules, racking, enclosures, and equipment shall be grounded in accordance with NEC 690.43 and Article 250.
+### The photovoltaic system DC disconnecting means and the isolating devices at the inverter input shall be furnished as NFPA 70 690.13 and 690.15 require, in the form indicated in the datasheet.
−### Module frames and racking shall be bonded either by a separate equipment grounding conductor or by the integrated bonding feature of a UL 2703 listed racking system.
+```datasheet
+label: Inverter DC Disconnecting Means
+type: radio
+options:
+ - "Integral to the inverter, load-break rated, lockable"
+ - "Separate enclosed DC-rated disconnect switch at the inverter"
+default: "Integral to the inverter, load-break rated, lockable"
+```
+### Nearly every string inverter and central inverter is furnished with an integral load-break DC disconnect that opens every ungrounded conductor and locks open, which is why the field defaults to it; a separate enclosed DC switch is added where the Authority Having Jurisdiction or the Owner requires a disconnect that is not part of the inverter, where the inverter is mounted out of reach, or where the inverter furnished has only an isolating device, and it is a DC-rated switch rated for the maximum system voltage, the circuit current, and the DC interrupting duty of a photovoltaic source. {note}
+
+### A DC disconnecting means shall open every ungrounded conductor of the circuit simultaneously, shall be rated for the maximum system voltage and the maximum circuit current, shall be load-break rated where NFPA 70 690.15 requires a load-break device, shall be lockable in the open position, and shall be marked with the voltage and the current as the Identification article requires.
+
+### An isolating device that is not load-break rated shall be marked as such and shall be opened only after the inverter has ceased to operate, and a connector used as an isolating device shall be of the tool-opened locking type NFPA 70 690.33 requires.
+
+### A DC arc does not extinguish at a current zero as an AC arc does, so a switch rated for AC and opened under DC load draws an arc that does not stop, which is why every DC disconnect carries a DC rating for the voltage and current it opens and why an isolating device that has none is opened only on a dead circuit. {note}
+
+## DC Surge Protection {toc}
+
+### Surge protection of the DC circuits shall be as indicated in the datasheet.
+
```datasheet
−label: Module / Racking Bonding Method
+label: DC Surge Protection
type: radio
options:
− - "UL 2703 integrated bonding (listed bonding components)"
− - "Separate equipment grounding conductor (EGC)"
−default: "UL 2703 integrated bonding (listed bonding components)"
+ - "Surge protective device integral to the inverter DC input"
+ - "Separate DC surge protective device at each inverter input and at each combiner"
+ - "No DC surge protection beyond the inverter listing"
```
−### A UL 2703 racking listing does not by itself satisfy equipment bonding unless its integrated bonding feature is specified and the listed bonding components are installed; otherwise a separate equipment grounding conductor is required. {note}
+### An array is a wide conductor loop on the highest part of a building, and a nearby strike induces a surge in it that reaches the inverter input; an integral device protects the inverter at no added cost and is furnished in most string inverters; a separate device at each combiner adds protection at the array end of long home runs on a ground mount or a large roof, and is the arrangement where the building has a lightning protection system or the site has a high flash density; no protection beyond the listing leaves the inverter's own input stage as the protection and is the arrangement of a small array on a low building in a low-flash region. The arrangement follows the array extent and the exposure, so the field carries no default. {note}
−### The equipment grounding conductor shall be sized per NEC 690.45 and 250.122 for the overcurrent device protecting the circuit.
+### A DC surge protective device shall be listed to UL 1449 for photovoltaic DC application, rated for the maximum system voltage, connected positive to negative and each pole to the equipment grounding conductor, and furnished with a status indicator readable without opening the enclosure.
−### The PV array grounding shall be connected to the building grounding electrode system and coordinated with [[sync/grounding-and-bonding]].
+### Where the building has a lightning protection system, the bonding of the array and the surge protection of the DC and AC circuits shall be coordinated with [[sync/lightning-protection]], and the surge protective device at the AC point of interconnection shall comply with [[sync/surge-protective-devices]].
−## Ground-Fault Protection {toc}
+# Interconnection {toc}
−### The PV system shall provide DC ground-fault protection in accordance with NEC 690.41, either integral to a transformerless inverter or by a separate listed ground-fault protection device.
+## Interconnection Method {toc}
−### Ground-fault protection detects insulation faults to ground that would otherwise persist undetected on an ungrounded or functionally grounded PV array and present a fire and shock hazard. {note}
+### The method by which the photovoltaic system connects to the premises wiring shall be as indicated in the datasheet.
−# Surge Protection {toc}
+```datasheet
+label: Interconnection Method
+type: radio
+drawing_ref: "the one-line diagram"
+options:
+ - "Load side of the service disconnecting means, under NFPA 70 705.12"
+ - "Supply side of the service disconnecting means, under NFPA 70 705.11"
+ - "Dedicated service for the photovoltaic system"
+default: deferred
+```
−## A PV array is an elevated, widely distributed conductor network that is exposed to lightning-induced and switching transients on both the DC and AC sides. {note}
+### A load-side connection backfeeds a breaker in an existing switchboard or panelboard and is limited by the bus rules of NFPA 70 705.12, of which the 120 percent rule is the best known: the inverter breaker and the main together are limited to 120 percent of the bus rating, with the inverter breaker at the opposite end of the bus from the main, and the alternatives of 705.12 let a power control system or a sum-of-breakers calculation serve where the bus will not; a supply-side connection taps the service conductors ahead of the service disconnect under 705.11, avoids the bus limits entirely, and requires a service-rated disconnect, service-entrance conductors, and the utility's agreement, which [[sync/electrical-service-entrance]] governs on its side of the tap; a dedicated service gives the array its own meter and service and is the arrangement of a tariff that meters generation separately. The method is a one-line decision and is deferred to that drawing. {note}
−### Surge protective devices shall be provided on the DC side and the AC side of the inverter in accordance with NEC 690.54 for the adopted code edition.
+### A load-side connection shall comply with NFPA 70 705.12, with the backfed breaker rated for the inverter output under 705.30, located as 705.12 requires, and the bus and the conductors it lands on checked against the applicable rule of 705.12(B), and the check shall be included in the action submittals.
−### DC surge protective devices shall be listed for DC PV use and rated for the maximum PV system voltage.
+### A supply-side connection shall be made with the tap conductors, the overcurrent device, and the disconnecting means NFPA 70 705.11 requires, and the disconnecting means, the service conductors, and the tap shall comply with [[sync/electrical-service-entrance]].
−### Surge protective devices shall be coordinated with [[sync/surge-protective-devices]].
+### The equipment at the point of interconnection and its bus ratings are governed by the standard for that equipment named in Scope, and the fault current contribution of the inverters, as the manufacturer publishes it with its duration, shall be stated in the product data for the study under [[sync/short-circuit-study]].
+## AC Disconnecting Means {toc}
+
+### The photovoltaic system AC disconnecting means shall be furnished as NFPA 70 690.13 and 705.20 require, and a utility-accessible disconnect shall be furnished as indicated in the datasheet.
+
```datasheet
−label: DC Surge Protective Device Type
+label: Utility-Accessible AC Disconnect
type: radio
+drawing_ref: "the utility interconnection requirements"
options:
− - "Type 1 (line side, lightning-exposed)"
− - "Type 2 (load side of disconnect)"
−default: "Type 2 (load side of disconnect)"
+ - "Visible-break, lockable disconnect at the location the utility requires, accessible to the utility at all hours"
+ - "Not required by the serving utility"
+default: deferred
```
+### Most utilities require a lockable, visible-break AC disconnect outdoors near the meter that their crews can open before working on the circuit, some accept the inverter's own disconnect or the listed anti-islanding function, and the requirement is stated in the utility's interconnection handbook, which is why the field is deferred to it. {note}
+
+### The AC disconnecting means shall open every ungrounded conductor of the inverter output, shall be rated for the inverter maximum output current and the available fault current at its terminals, shall be lockable in the open position, shall be of the form the Device Family article of [[sync/enclosed-switches-and-disconnects]] describes for a UL 98 switch or a UL 489 breaker, and shall be marked as the Identification article of this standard requires.
+
+### The AC disconnecting means of a system interconnected on the supply side of the service disconnect shall be listed as suitable for use as service equipment.
+
+## Interconnection Application {toc}
+
+### The responsibility for the utility interconnection application shall be as indicated in the datasheet.
+
```datasheet
−label: AC Surge Protective Device Type
+label: Interconnection Application Responsibility
type: radio
options:
− - "Type 1 (service entrance)"
− - "Type 2 (inverter output / panel)"
−default: "Type 2 (inverter output / panel)"
+ - "The Contractor prepares and files the application in the Owner's name and carries it to permission to operate"
+ - "The Owner or the Engineer files the application and the Contractor furnishes the technical data and the as-built documents"
```
−### Where the building has a lightning protection system, the PV surge and bonding provisions shall be coordinated with it per [[sync/lightning-protection]].
+### The Contractor filing the application is the arrangement of a design-build project and puts the party that controls the schedule and the equipment data in contact with the utility; the Owner or the Engineer filing is the arrangement of a design-bid-build project where the application precedes the award and the Contractor inherits a conditional approval. Both are routine, so the field carries no default. {note}
−# Mounting and Racking {toc}
+### The interconnection application shall be filed at the earliest date the equipment data permits, and the Contractor shall report to the Engineer of Record within five working days any utility requirement that changes the equipment, the settings, the export limit, or the point of interconnection from the reviewed submittals.
+### The utility's study and approval run from weeks on a small system to a year or more on a large one or on a constrained circuit, and the interconnection, not the construction, is what sets the date the array produces; a project that files late discovers the circuit's hosting capacity after the inverters are on the wall. {note}
+
+# Mounting System {toc}
+
## Mounting Type {toc}
−### The mounting system shall be one of the configurations scheduled below, selected to suit the roof or ground condition, the structural capacity, and the roofing warranty.
+### The mounting type of the array shall be as indicated in the datasheet.
```datasheet
label: Mounting Type
type: select
options:
− - "Ballasted, non-penetrating (flat roof)"
− - "Attached / flashed penetration (flat or low-slope roof)"
− - "Standing-seam metal roof clamp"
− - "Ground-mount fixed-tilt"
− - "Ground-mount single-axis tracker"
−default: "Ballasted, non-penetrating (flat roof)"
+ - "Roof, mechanically attached through the roof covering"
+ - "Roof, ballasted, no penetrations"
+ - "Roof, ballasted with supplementary attachments"
+ - "Roof, standing-seam clamps"
+ - "Ground mount, fixed tilt"
+ - "Ground mount, single-axis tracker"
+ - "Carport or canopy"
```
−### Racking shall be listed to UL 2703 and installed within the limits of its listing for tilt, span, and clamping.
+### A mechanically attached roof array is the lightest, holds on any slope, and puts a flashed penetration through the roof at every attachment, each one needing the roofing manufacturer's acceptance to keep the roof warranty in force; a ballasted array penetrates nothing and holds by weight, which adds 3 to 6 psf of dead load, more at the array edges and corners, requires a roof slope of a few degrees or less and a membrane that tolerates the bearing of the ballast trays, and in a high seismic category or a high wind zone needs more weight than many roofs carry; a ballasted array with a few attachments trades some penetrations for most of the weight and is the arrangement where the structure carries neither alone; standing-seam clamps hold without penetrating or ballasting, with the panel and the seam carrying every load, and are the arrangement wherever that roof exists; a fixed-tilt ground mount costs the land, the foundations, and the fence, and nothing on the roof; a single-axis tracker follows the sun east to west, yields 15 to 25 percent more energy than fixed tilt at the latitude of most of the country, and adds motors, controllers, a wind stow, and maintenance; a carport or canopy shades the parking, carries the highest structure cost per watt, and is built where the roof is unavailable and the land is already paved. The type follows the site and the structure, so the field carries no default. {note}
−### The array layout shall not be finalized until the roof or foundation structural capacity is confirmed in writing by a licensed structural engineer.
+### The mounting system shall be installed within the limits of its UL 2703 listing and its delegated design for module orientation, clamp location within the module's clamp zone, span, tilt, and ballast or attachment quantity, and no module shall be clamped outside the zone its load rating was established in.
−### Confirming roof structural capacity only after the array layout is fixed is a common and costly defect; ballast dead load and concentrated uplift at corners and edges shall be checked against the structure before layout, not after.
+### The array and its equipment shall be kept clear of the fire-service pathways, the setbacks, the smoke ventilation areas, and the roof access the adopted fire code requires on the roof, as indicated on [[drawing: the array layout plan]], and the pathways shall remain clear of conduit, cable, and combiner boxes.
−## Ballasted Roof Mounting {toc}
+### IFC Section 1205 and NFPA 1 Section 11.12 set the perimeter pathways, the ridge setbacks, the access aisles through a large array, and the ventilation opportunities a roof keeps clear so that the fire department can reach and vent the roof with the array in place, and the widths and the array size thresholds in them are the fire code's rather than a project selection; a layout that fills the roof to the parapet is the most frequent cause of a fire plan review rejection. {note}
−### Ballasted, non-penetrating racking shall distribute dead load within the allowable roof loading and shall include slip and wind-uplift restraint designed under ASCE/SEI 7.
+## Attached Roof Mounting {toc}
−```datasheet
−label: Ballasted Array Distributed Dead Load
−type: range
−unit: psf
−min: 3
−max: 6
−step: 0.5
−default: 4
−```
+### Where the array is mechanically attached, each attachment shall be fastened to the structural framing or the structural deck as the delegated design states, through a flashed penetration or a curb constructed under [[sync/membrane-roofing]] for a membrane roof and under the standard for the roof covering in place for another, and no attachment shall be fastened to the deck alone unless the delegated design and the structural engineer of record accept it.
−### The ballasted system shall include a slip sheet or protection layer compatible with the roof membrane to prevent abrasion of the roofing.
+### The attachment flashing, the sealant, and the penetration detail shall be those the roofing manufacturer accepts in writing for the roof covering in place, and the acceptance shall state that the roof warranty remains in force with the array installed.
−### A ballasted system imposes its full weight as roof dead load while also resisting wind uplift; both the gravity load and the uplift restraint shall be designed, because a system adequate for gravity may still lift at roof corners.
+### The attachment layout shall be as indicated on [[drawing: the delegated mounting design drawings]], and an attachment moved in the field to clear a purlin, a drain, or a seam shall be relocated only within the tolerance the delegated design states.
−## Attached and Penetrating Mounting {toc}
+## Ballasted Roof Mounting {toc}
−### Roof penetrations shall be flashed and sealed using assemblies approved by the roofing manufacturer.
+### Where the array is ballasted, the ballast shall be the blocks the delegated design specifies by weight and location, placed in the trays the racking listing provides, and the installed ballast shall be verified block by block against the ballast plan before the modules are set.
−### The roof penetration details and the roofing manufacturer's approval shall be coordinated to preserve the existing roof warranty.
+### A ballasted system shall be set on a slip sheet or protection pad compatible with the roof membrane as the roofing manufacturer requires, and the roofing manufacturer's acceptance shall cover the pad, the ballast weight, and the point loads at the tray feet.
−### Omitting roof penetration flashing and warranty coordination is a frequent source of leaks and voided roof warranties; the roofing manufacturer's written approval of the attachment detail shall be obtained before penetrations are made.
+### Where [[parameter: seismic-design-category]] is D, E, or F, an unattached ballasted array shall comply with the displacement-based provisions of ASCE/SEI 7 Section 13.6.12 for unattached rooftop solar arrays, with the clearances to the roof edge, the parapet, the equipment, and the pathways that the calculated displacement requires, or the array shall be attached.
−### The penetration attachment pattern and locations shall be shown on the drawings [[drawing: roof attachment layout]].
+### Ballast holds an array still only until the wind or the earthquake moves it, and an array that slides a foot in a seismic event takes its wiring with it; ASCE/SEI 7 permits an unattached array in the higher categories only where the calculated slide is kept inside a clear zone, which is why the clearance to every edge and obstruction is part of the delegated design and not a field adjustment. {note}
−## Standing-Seam Metal Roof Mounting {toc}
+## Standing-Seam Roof Mounting {toc}
−### Clamps for standing-seam metal roofs shall be listed for the specific seam profile and shall not penetrate the roof panel.
+### Where the array is mounted on a standing-seam metal roof, the clamps shall be listed for the specific seam profile and panel gauge, shall not penetrate the panel, and the confirmation that the seam and the panel carry the clamp reactions shall be obtained under [[sync/metal-roof-panels]] before the racking is ordered.
−### Standing-seam clamp loads shall be coordinated with the metal roof manufacturer to confirm the seam and panel can carry the clamp reactions.
+### The clamp spacing and the clamp torque shall be as the delegated design and the clamp manufacturer's instructions state for the seam profile, and the clamps shall accommodate the thermal movement of the panels without loosening.
−## Ground-Mount Foundations {toc}
+## Ground Mounting {toc}
−### Ground-mount foundations shall be designed by a licensed engineer using a project geotechnical report.
+### Where the array is ground-mounted, the foundation type shall be as indicated in the datasheet.
```datasheet
…2 unchanged lines
options:
- "Driven steel pile"
− - "Helical screw pile"
− - "Ballasted concrete (non-penetrating)"
− - "Cast-in-place concrete pier"
−default: "Driven steel pile"
+ - "Helical pile"
+ - "Ground screw"
+ - "Drilled concrete pier"
+ - "Ballasted precast or cast-in-place footing"
```
−### Single-axis trackers shall be installed within the manufacturer's wind-stow and range-of-motion limits and shall be designed for the site wind loads under ASCE/SEI 7. {note}
+### A driven steel pile is the lowest-cost foundation in soil that takes a pile and is set by a machine at a rate of hundreds a day; a helical pile is screwed in, has its capacity read from the installation torque, and suits a soil with cobbles or a shallow refusal; a ground screw is a smaller helical for lighter racking; a drilled concrete pier suits rock or a soil that will not hold a pile, at the highest cost per foundation; a ballasted footing sits on the surface and is the foundation of a landfill cap, a brownfield, or a site where driving is prohibited. The type follows the geotechnical report, so the field carries no default, and the foundations as constructed are governed by [[sync/deep-foundations]] for the piles and piers and by [[sync/concrete-pads]] for a cast-in-place footing. {note}
−### Ground-mount work requires a separate structural and geotechnical scope; pile capacity, frost depth, and corrosion of below-grade steel shall be addressed in that scope and are not specified here. {note}
+### The foundations shall be designed under the delegated design from a geotechnical report for the site and from a pull-out and lateral load test program on test piles at the site where the delegated design requires one, with the embedment set below [[parameter: frost-depth]] where frost heave governs.
−# Fire-Service Access {toc}
+### A single-axis tracker shall stow at the wind speed its listing and delegated design state, shall carry a backup power source or a mechanical lock that stows it on loss of power, and shall be furnished with the controller, the sensors, and the communication to the monitoring system that report its position and its faults.
−## Rooftop access pathways, setbacks, and array aisles shall be provided in accordance with the adopted International Fire Code Chapter 12 and NFPA 1, as amended by the AHJ. {note}
+### The ground-mount array shall be enclosed by fencing constructed under [[sync/fencing-and-gates]] where the drawings so indicate, with the clearance between the fence and the array that the delegated design and NFPA 70 110.26 require, and the equipment pads, the vegetation management, and the grading beneath the array shall be as indicated on [[drawing: the civil site plan]].
−### A clear ridge setback shall be maintained along the roof ridge as required by the adopted fire code.
+## Carport and Canopy Mounting {toc}
−### Perimeter access pathways shall be maintained around the array as required by the adopted fire code.
+### Where the array is mounted on a carport or canopy, the structure shall be designed and constructed under [[sync/structural-steel-framing]] for the array loads of the delegated design, with the clear height, the column protection, and the lighting indicated on [[drawing: the site plan and the structural drawings]], and the racking, the modules, and the wiring shall comply with this standard.
−### Mid-array access aisles shall be provided for arrays exceeding the area threshold of the adopted fire code.
+### The wiring beneath a canopy shall be concealed within the structure or in raceway, protected from vehicle impact to a height of 8 ft above the pavement, and arranged so that water shed by the modules is collected and discharged clear of the parking spaces.
+# Bonding of the Array {toc}
+
+## The modules, the racking, and every exposed non-current-carrying metal part of the array shall be bonded and connected to the equipment grounding conductor in accordance with NFPA 70 690.43 and Article 250, by the method indicated in the datasheet.
+
```datasheet
−label: Ridge / Perimeter Setback Width
−type: range
−unit: in
−min: 18
−max: 48
−step: 6
−default: 36
+label: Module and Racking Bonding Method
+type: radio
+options:
+ - "Integrated bonding through the UL 2703 listed clamps and splices, with a listed ground lug per row"
+ - "Separate bonding jumper and equipment grounding conductor to every module and rail"
+default: "Integrated bonding through the UL 2703 listed clamps and splices, with a listed ground lug per row"
```
−### Fire-service setbacks and pathways shall not be reduced or value-engineered out without the written concurrence of the AHJ; pathways removed to gain array area are a common cause of AHJ rejection and forced rework.
+## A UL 2703 racking system whose clamps and splices are listed as bonding devices bonds the module frames and the rails to one another through the clamps themselves, so that one equipment grounding conductor connection per row through a listed lug grounds the whole row, and it is the method of nearly every framed-module installation, which is why the field defaults to it; a separate jumper to every module and rail is the method of a racking whose clamps are not listed for bonding, of a frameless module, and of an Owner who requires a visible conductor, at the cost of a lug and a jumper at every module. {note}
−### The rooftop fire-service access layout shall be shown on the drawings [[drawing: fire access pathway plan]].
+## Where integrated bonding is selected, the clamps, the splices, and the ground lugs shall be the listed bonding components of the racking system installed at the torque the listing states, and the bonding path shall not depend on a component the listing does not name as a bonding device.
+## The equipment grounding conductor of each source and output circuit shall be sized under NFPA 70 690.45 and 250.122, shall run with the circuit conductors, and shall be connected to the grounding electrode system of the building or the structure as [[sync/grounding-and-bonding]] requires, with any auxiliary electrode at the array furnished under that standard.
+
+## Where the racking is on a standing-seam roof or a structure that is itself bonded to the lightning protection system, the bonding between the array and that system shall be as [[sync/lightning-protection]] requires.
+
# Metering and Monitoring {toc}
## Production Metering {toc}
−### A revenue-grade production meter shall be provided to measure PV energy production independent of the inverter portal.
+### The production of the photovoltaic system shall be metered as indicated in the datasheet.
−### The production meter shall meet ANSI C12.20 accuracy class as scheduled below.
−
```datasheet
−label: Production Meter Accuracy Class
+label: Production Metering
type: radio
options:
− - "ANSI C12.20 Class 0.5"
− - "ANSI C12.20 Class 0.2"
−default: "ANSI C12.20 Class 0.5"
+ - "Revenue-grade meter on the inverter output, ANSI C12.1 accuracy class"
+ - "Production reported by the inverters alone"
+ - "Production meter furnished by the serving utility or the incentive program"
```
−### Relying on the inverter portal alone for production data, without a separate revenue-grade meter, is a common omission that prevents verified billing and incentive reporting. {note}
+### A revenue-grade meter on the inverter output records the production independently of the inverters and is what settles a production guarantee, an incentive payment, a renewable energy certificate, or a power purchase agreement, at the cost of a meter and its current transformers; inverter-reported production is accurate to a few percent and costs nothing, and it is unverifiable by a third party and lost when an inverter is replaced; a utility or program meter is furnished and read by the party that pays and is the arrangement of a feed-in or performance-based incentive. The arrangement follows who pays for the energy, so the field carries no default, and the meter as a product is governed by [[sync/electrical-power-monitoring]]. {note}
−## Monitoring {toc}
+### Where a revenue-grade meter is selected, it shall comply with [[sync/electrical-power-monitoring]] for the accuracy class, the current transformers, and the communications, shall be read by the monitoring system, and shall be the instrument the performance acceptance test and the production guarantee are settled against.
−### A monitoring system shall report system production, inverter status, and fault alarms.
+## Monitoring Granularity {toc}
−### Module-level monitoring shall be provided where DC optimizers or microinverters are used, to report per-module performance.
+### The monitoring system shall record the production and the status of the system at the granularity indicated in the datasheet.
```datasheet
label: Monitoring Granularity
type: radio
options:
− - "System-level (inverter)"
− - "String-level"
− - "Module-level (MLPE)"
−default: "System-level (inverter)"
+ - "Inverter level"
+ - "String level"
+ - "Module level"
```
−# Interconnection {toc}
+### Inverter-level monitoring reports the output and the faults of each inverter and finds a failed inverter the same day and a failed string never; string-level monitoring reads the current of each string at the inverter input or the combiner and finds a failed string, an open fuse, or a shaded row by comparison with its neighbors, and it is what a commercial array of any size is maintained from; module-level monitoring comes with optimizers and microinverters and finds a single degraded module, at the cost of those devices and the data they generate. The granularity follows the architecture and the maintenance organization, so the field carries no default. {note}
−## The PV system shall interconnect with the building electrical system by one of the paths scheduled below, in accordance with NFPA 70 Article 705.
+### The monitoring system shall record, at an interval of fifteen minutes or shorter, the AC energy and power of each inverter, the DC voltage and current of each input at the granularity selected, the inverter status and every fault code, the production meter reading where a meter is furnished, and the sensor readings selected under this standard, and shall retain the data for not less than the production guarantee term or five years, whichever is longer.
+### The monitoring system shall alarm by electronic message to the Owner's designated recipients on an inverter fault, a ground fault, an arc fault, a rapid shutdown operation, a communication loss exceeding one hour, and a daily production below a threshold the Owner sets, and the alarm configuration shall be demonstrated at commissioning.
+
+## Monitoring Instruments {toc}
+
+### The monitoring system shall be furnished with the instruments indicated in the datasheet, installed in accordance with IEC 61724-1 for the monitoring class the performance acceptance method selected under this standard requires.
+
```datasheet
−label: Interconnection Path
−type: radio
+label: Monitoring Instruments
+type: checkbox
options:
− - "Load-side backfeed (705.12, 120% busbar rule)"
− - "Supply-side connection (705.11, ahead of service disconnect)"
−default: "Load-side backfeed (705.12, 120% busbar rule)"
+ - "Plane-of-array irradiance sensor"
+ - "Reference cell of the module technology furnished"
+ - "Module back-of-cell temperature sensor"
+ - "Ambient temperature sensor"
+ - "Wind speed sensor"
+ - "Soiling measurement"
+constraint: all_of
```
−### A load-side backfeed connection shall comply with the busbar and overcurrent-device limits of NEC 705.12, including the 120% busbar allowance where applicable.
+### A plane-of-array irradiance sensor and a module temperature sensor are what turn a production figure into a performance ratio, and without them a low month cannot be told from a cloudy one; a reference cell of the same technology as the modules responds to the spectrum and the angle as the modules do and is the instrument IEC 61724-2 settles a capacity test with; ambient temperature and wind speed feed a model that predicts the module temperature; a soiling measurement separates dirt from degradation on a dusty or agricultural site. A production guarantee cannot be settled without the first two, which is why they are selected wherever a guarantee is. {note}
−### A supply-side connection shall be made ahead of the service disconnecting means in accordance with NEC 705.11.
+## Communications {toc}
−### The interconnection shall not be energized until the serving utility grants permission to operate following any required witness test.
+### The monitoring system shall communicate with the Owner's systems by the interfaces indicated in the datasheet.
−### The point of interconnection and the backfeed overcurrent device shall be coordinated with the existing distribution equipment per [[sync/panelboards]].
+```datasheet
+label: Monitoring Interfaces
+type: checkbox
+options:
+ - "Manufacturer-hosted monitoring portal with Owner administrator access"
+ - "Modbus TCP or SunSpec Modbus to the building automation system"
+ - "IEEE 2030.5, IEEE 1815, or SunSpec Modbus interface to the serving utility as the interconnection agreement requires"
+ - "Data export by open application programming interface to a third-party platform"
+default:
+ - "Manufacturer-hosted monitoring portal with Owner administrator access"
+constraint: all_of
+```
−# Energy Storage Interface {toc}
+### The inverter manufacturer's portal is the interface every system ships with and the one the warranty and the production guarantee are read through, which is why it is the default; a Modbus connection lets the building automation system display and log the production under [[sync/building-automation-system]]; the utility interface is the one IEEE 1547 requires an interactive resource to present where the utility uses it; an open interface lets an Owner with a portfolio read every site into one platform. {note}
−## Where the PV system is specified as storage-ready or is interfaced with a battery energy storage system, the DC- or AC-coupling interface shall be coordinated with the storage equipment under NFPA 70 Article 706. {note}
+### The monitoring gateway and the inverters shall support authenticated and encrypted communication, shall be placed on a network segment the Owner controls behind a gateway the Owner administers, and the manufacturer's remote access shall be logged and revocable by the Owner, with the network cabling under [[sync/structured-cabling]].
−### The PV-to-storage coupling method, where storage is provided, shall be documented and coordinated with [[sync/battery-energy-storage-systems]].
+# Identification {toc}
−### Storage-ready provisions shall reserve the physical space, conductor pathways, and interconnection capacity required for the future storage equipment so that later addition does not require rework of the PV interconnection.
+## Every label, placard, and marking this article requires shall be permanent, weather-resistant, and legible for the life of the system, of the material, lettering, and attachment [[sync/equipment-labeling]] requires, and red with white lettering where NFPA 70 690.56 requires that color.
−# Labeling {toc}
+## A rapid shutdown placard shall be installed at the service equipment and at each initiation device in accordance with NFPA 70 690.56(C), stating the type of rapid shutdown furnished and the conductors it controls, with the diagram and the wording the adopted edition requires, and each initiation device shall be labeled as the rapid shutdown switch for the solar PV system.
−## All field labels and placards required by NEC Article 690, including the rapid-shutdown labels of 690.56 and the directory of power sources, shall be provided.
+## A permanent plaque or directory shall be installed at the service equipment and at each point of interconnection in accordance with NFPA 70 705.10, identifying every power source on the premises and the location of every disconnecting means, with the plaque furnished under [[sync/equipment-labeling]].
−## Labels shall be permanent, weather-resistant, and legible for the system service life.
+## Each DC photovoltaic circuit disconnecting means and each combiner shall be marked in accordance with NFPA 70 690.53 with the maximum circuit voltage and the maximum circuit current, as calculated under this standard for the adopted edition, and the disconnecting means shall be marked as the photovoltaic system disconnect in accordance with 690.13.
−## Field labeling shall be coordinated with [[sync/equipment-labeling]].
+## The point of interconnection shall be marked in accordance with NFPA 70 690.54 with the rated AC output current and the nominal operating AC voltage of the system.
+## A backfed breaker at a load-side interconnection shall be marked in accordance with NFPA 70 705.12 to warn that it is a power source output connection and is not to be relocated, and the equipment it is installed in shall be marked with the sum of the ratings of the sources connected to its bus.
+
+## DC raceways, cable trays, enclosures, and junction boxes inside a building shall be marked in accordance with the provisions of NFPA 70 690.31 for DC circuits on or in a building, at intervals not exceeding 10 ft, on every section separated by a wall or a ceiling, and on every enclosure, with the warning that identifies a photovoltaic power source.
+
+## Each inverter, combiner, and disconnect shall carry a nameplate stating its designation on the one-line diagram, the circuits it serves, and the location of its source, and the arc-flash warning label required under [[sync/arc-flash-study]] where the study covers the AC equipment.
+
+## Where the system is multimode or is paired with storage, the disconnecting means and the service equipment shall carry the additional markings of NFPA 70 Article 706 and 705.10 for the storage, as [[sync/battery-energy-storage-systems]] requires.
+
+# Testing {toc}
+
+## Commissioning Tests {toc}
+
+### The photovoltaic system shall be commissioned in accordance with IEC 62446-1 and this standard after installation is complete and before it is operated in parallel with the utility, and the commissioning shall include the tests indicated in the datasheet.
+
```datasheet
−label: Required PV Field Labels
+label: Commissioning Tests
type: checkbox
options:
− - "Rapid-shutdown switch label (690.56(C))"
− - "Rapid-shutdown system type placard (690.56(C))"
− - "Directory of multiple power sources (705.10)"
− - "DC disconnect and maximum voltage marking (690.13 / 690.53)"
− - "AC point-of-interconnection marking"
−default: ["Rapid-shutdown switch label (690.56(C))", "Directory of multiple power sources (705.10)", "DC disconnect and maximum voltage marking (690.13 / 690.53)"]
+ - "Continuity of the equipment grounding and bonding of every module row and enclosure"
+ - "Polarity of every source and output circuit"
+ - "Open-circuit voltage of every source circuit with irradiance and temperature recorded"
+ - "Operating or short-circuit current of every source circuit with irradiance recorded"
+ - "Insulation resistance of every DC circuit"
+ - "Functional test of every inverter, disconnect, ground-fault and arc-fault function, and alarm"
+ - "Rapid shutdown operation and timing from every initiation device"
+ - "Anti-islanding and IEEE 1547 settings verification, witnessed by the utility where it requires"
+ - "Current-voltage curve trace of every source circuit"
+ - "Infrared thermography of the modules, the connectors, and the terminations under load"
+ - "Torque verification of terminations"
+ - "Monitoring and production meter data verification against field readings"
+default:
+ - "Continuity of the equipment grounding and bonding of every module row and enclosure"
+ - "Polarity of every source and output circuit"
+ - "Open-circuit voltage of every source circuit with irradiance and temperature recorded"
+ - "Operating or short-circuit current of every source circuit with irradiance recorded"
+ - "Insulation resistance of every DC circuit"
+ - "Functional test of every inverter, disconnect, ground-fault and arc-fault function, and alarm"
+ - "Rapid shutdown operation and timing from every initiation device"
+ - "Anti-islanding and IEEE 1547 settings verification, witnessed by the utility where it requires"
+ - "Torque verification of terminations"
+ - "Monitoring and production meter data verification against field readings"
+constraint: all_of
```
−# Testing {toc}
+### The default set is the Category 1 test sequence of IEC 62446-1, which every grid-connected system receives, plus the rapid shutdown and the utility tests NFPA 70 and the interconnection agreement add; the curve trace and the thermography are the Category 2 tests, added on a system large enough that a string a few percent low or a connector a few degrees warm is worth finding on the first day rather than in the first year. {note}
−## Acceptance Testing {toc}
+### Open-circuit voltage and current readings shall be taken with the irradiance and the module temperature recorded at the time of each reading, corrected to standard test conditions, and compared string to string, and a string whose corrected voltage or current departs from the mean of its group by more than 5 percent shall be investigated and the cause corrected before acceptance.
−### The PV system shall be commissioned and acceptance-tested before energization in accordance with ANSI/NETA ATS and the manufacturer's commissioning procedures.
+### The insulation resistance of each DC circuit shall be measured at the test voltage IEC 62446-1 states for the system voltage, with the modules connected and the inverter and the surge protective devices isolated, and shall be not less than the minimum IEC 62446-1 states for the array size.
−### Each PV source circuit shall be tested for correct polarity, open-circuit voltage, and operating current, and the readings shall be recorded.
+### The rapid shutdown test shall operate each initiation device in turn, measure the voltage at the array boundary and within it at the time limit, and confirm that every inverter and every system on the building responded, and the test shall be repeated after any change to the inverters or the module-level devices.
−### DC and AC conductor insulation resistance shall be tested and recorded prior to energization.
+### The commissioning tests shall be performed by the party indicated in the datasheet.
−### The rapid-shutdown function shall be tested to confirm the controlled conductors reach the required voltage within 30 seconds of initiation.
+```datasheet
+label: Commissioning Test Performer
+type: radio
+options:
+ - "Independent testing firm qualified under the acceptance testing standard"
+ - "Installing contractor's own technicians, with the inverter manufacturer's commissioning service for the inverters"
+```
−### The ground-fault and arc-fault protection functions shall be tested to confirm correct operation.
+### An independent firm reports against a published standard with no stake in the result and is what a financed system or a production guarantee is accepted on; the installing contractor's own technicians, with the inverter maker commissioning its own equipment, is the arrangement of most small and mid-size systems and costs the project only the day. Which the Owner wants follows the size of the system and who is relying on the report, so the field carries no default, and the AC equipment at the point of interconnection is tested under [[sync/electrical-acceptance-testing]] in either case. {note}
−### The anti-islanding function shall be confirmed by the utility witness test or by the inverter listing where a witness test is waived.
+### A circuit, an inverter, or a function that fails a commissioning test shall not be placed in service, the Contractor shall report the failure to the Engineer of Record within one working day with the measured values, and the cost of the correction and of every repeated test shall be borne by the Contractor.
+## Performance Acceptance {toc}
+
+### The performance of the photovoltaic system shall be accepted by the method indicated in the datasheet.
+
```datasheet
−label: Required Acceptance Tests
−type: checkbox
+label: Performance Acceptance Method
+type: radio
options:
− - "Source-circuit polarity, Voc, and operating current"
− - "Conductor insulation resistance"
− - "Rapid-shutdown function (30 s verification)"
− - "Ground-fault protection function"
− - "Arc-fault protection function"
− - "Anti-islanding / utility witness test"
−default: ["Source-circuit polarity, Voc, and operating current", "Conductor insulation resistance", "Rapid-shutdown function (30 s verification)", "Anti-islanding / utility witness test"]
+ - "Commissioning tests only, no performance test"
+ - "Capacity test in accordance with IEC 61724-2 after commissioning"
+ - "Energy performance evaluation in accordance with IEC 61724-3 over the first twelve months"
```
−### Any test result outside the acceptance criteria shall be corrected and retested before the system is placed in service.
+### The commissioning tests prove that every circuit works and say nothing about whether the array produces what the energy model promised; a capacity test under IEC 61724-2 measures the power at a measured irradiance and temperature over a few clear days after commissioning and compares it with the model at the same conditions, which settles the installed capacity before final payment; an energy evaluation under IEC 61724-3 compares the metered energy over a year with the model run on the measured weather, which settles the production guarantee and catches a soiling, a shading, or an availability loss a capacity test cannot see. The method follows whether a production guarantee is carried, so the field carries no default. {note}
+### Where a capacity test is selected, the measured capacity corrected to the reference conditions shall be not less than the percentage of the modeled capacity indicated in the datasheet, and a system that measures below it shall be corrected and retested at the Contractor's cost or the shortfall settled as the Contract provides.
+
+```datasheet
+label: Capacity Test Acceptance, Measured as a Percentage of Modeled Capacity
+type: range
+unit: '%'
+options:
+ min: 90
+ max: 100
+ step: 1
+constraint: min
+```
+
+### The modeled capacity is the design value and the installed array is expected to reach it, and an acceptance below 100 percent recognizes the uncertainty of the irradiance sensor, the temperature correction, and the meter, which together run a few percent; where the threshold is set depends on how the project treats that uncertainty, so the field carries no default. {note}
+
+## Owner Training {toc}
+
+### The Contractor shall conduct training for the Owner's operating staff before substantial completion, of the duration indicated in the datasheet, covering the monitoring portal and its alarms, the normal and the emergency shutdown of the system including rapid shutdown, the restart after a utility outage or a fault, the isolation of a string for service, the cleaning and the inspection schedule the warranties require, and the records the production guarantee requires the Owner to keep.
+
+```datasheet
+label: Owner Training Duration
+type: range
+unit: hours
+options:
+ min: 2
+ max: 16
+ step: 1
+constraint: min
+```
+
+### Two hours covers a string-inverter array whose operation is a portal and whose maintenance is an annual inspection; a day covers a tracker array, a central inverter, or a multimode system with an island mode the Owner's staff will operate. The duration follows the system, so the field carries no default. {note}
+
+# Installation {toc}
+
+## Array Installation {toc}
+
+### Modules shall be handled by their frames or by the edge-lift the manufacturer specifies for a frameless module, shall not be walked on, stood on, or used as a work surface, shall not be set down on a corner, and shall not be lifted or carried by their junction boxes, leads, or connectors.
+
+### A cell cracks under a boot and keeps producing, and the crack opens over a few winters until the string is a few percent low and the module is out of warranty for mishandling; the damage is invisible on installation day and is seen later only by electroluminescence, which is why handling is a requirement and not a care note. {note}
+
+### Modules shall be installed in the orientation and the clamp zones the module listing and the delegated design permit, with the clamp torque the racking manufacturer states and verified with a calibrated tool, and the module serial numbers shall be recorded by position before the modules are covered by the next row.
+
+### The work on a roof shall be performed with the fall protection OSHA 29 CFR 1926 Subpart M requires, and the anchors that remain for the Owner's maintenance shall be furnished under [[sync/fall-protection-anchorage]].
+
+### The roof covering, the flashing, the drains, and the walkway pads shall be protected during the installation, and damage to the roof covering caused by the photovoltaic work shall be repaired by the roofing contractor under the roofing manufacturer's details at the Contractor's cost.
+
+### Roof penetrations shall be flashed and sealed by the roofing contractor or by an installer the roofing manufacturer accepts, under the roofing standard for the covering in place, and no attachment shall be made until the roofing manufacturer's written acceptance under the Informational Submittals article is in hand.
+
+## Electrical Installation {toc}
+
+### Every conductor termination shall be torqued to the manufacturer's published value with a calibrated torque tool in accordance with NFPA 70 110.14(D), and the values applied shall be recorded in the commissioning report.
+
+### Source circuits shall be connected to the inverter or the combiner only after the polarity and the open-circuit voltage of each have been measured and recorded, and no DC connector shall be opened or closed under load.
+
+### The inverters shall be mounted at the height, the spacing, and the clearance from the roof, the wall, and each other that the manufacturer's instructions require for cooling, shaded from direct sun where the manufacturer so requires, and with the working space of NFPA 70 110.26 in front of every enclosure the disconnects or the fuses are serviced from.
+
+### The DC and the AC conductors beyond the array, the raceways, the supports, and the penetrations shall be installed under [[sync/conductors-and-cables]], [[sync/raceways-and-conduit]], and, below grade, [[sync/underground-ductbank]], with the rooftop raceways supported clear of the roof surface and the expansion fittings the raceway standard requires.
+
+### The system shall not be energized or operated in parallel with the utility until the commissioning tests this standard names for energization have passed, the Authority Having Jurisdiction has inspected the installation, and the utility's permission to operate is in hand.
+
# Delivery, Storage, and Handling {toc}
−## Modules shall be delivered in the manufacturer's packaging and stored protected from impact, moisture, and excessive load until installed.
+## Modules shall be delivered on the manufacturer's pallets in the manufacturer's packaging, with the flash test data and the serial numbers of each pallet, and shall be inspected at receipt for broken glass, damaged frames, damaged connectors, and conformance with the reviewed submittal.
−## Modules shall not be lifted, carried, or set down by their junction boxes, cables, or connectors.
+## Module pallets shall be stored upright on a level surface, protected from rain and standing water, strapped against wind, and not stacked higher than the manufacturer permits, and modules removed from a pallet shall be stored on edge in the manufacturer's orientation and not laid flat.
−## Inverters and electronic equipment shall be stored within the manufacturer's temperature and humidity limits and protected from construction dust and moisture.
+## Inverters, module-level electronics, and monitoring equipment shall be stored within the manufacturer's published temperature and humidity range, off the ground, and protected from construction dust and water until installed, and an inverter stored outdoors shall be in its sealed packaging or installed on its mount with its covers closed.
−## Modules shall not be stepped on or stacked beyond the manufacturer's permitted stacking height, because mechanical microcracking degrades output without visible damage.
+## Racking shall be stored off the ground and sorted by component, and galvanized or anodized components shall be protected from standing water and from contact with dissimilar metals during storage.
−# Warranty {toc}
+## A module with broken glass, a cracked backsheet, a damaged connector, or a frame deformed enough to open the glass edge seal shall be rejected and removed from the site, and shall not be installed or kept as a spare.
−## The Contractor shall provide the manufacturer's product warranties for modules, inverters, and racking, and an installation workmanship warranty.
+# Warranty and Production Guarantee {toc}
+## Module Warranties {toc}
+
+### The module manufacturer shall warrant the modules against defects in materials and workmanship for not less than the term indicated in the datasheet, measured from the date of substantial completion.
+
```datasheet
−label: Module Product Warranty
+label: Module Product Warranty Term
type: range
−unit: yr
−min: 10
−max: 25
−step: 1
−default: 12
+unit: years
+options:
+ min: 10
+ max: 30
+ step: 1
+constraint: min
```
+### The module manufacturer shall warrant the power output of the modules for not less than the term indicated in the datasheet, with the power at the end of the term not less than the percentage of nameplate power indicated in the datasheet and a linear or stepped degradation schedule between.
+
```datasheet
−label: Module Power Performance Warranty
+label: Module Performance Warranty Term
type: range
−unit: yr
−min: 20
−max: 30
−step: 1
+unit: years
+options:
+ min: 20
+ max: 30
+ step: 1
default: 25
+constraint: min
```
```datasheet
−label: Inverter Warranty
+label: Module Power Retained at the End of the Performance Warranty
type: range
−unit: yr
−min: 5
−max: 25
−step: 1
−default: 10
+unit: '% of nameplate'
+options:
+ min: 80
+ max: 95
+ step: 0.5
+constraint: min
```
+### A twenty-five-year performance warranty is the term nearly every module is sold with, which is why that field defaults to it, and thirty years is offered on glass-glass product lines; the product warranty, which covers the module failing rather than fading, has moved from ten or twelve years to fifteen or twenty-five on the common product lines and has no single norm, so that field carries none. The retained power follows the technology: a passivated emitter module is warranted in the low to mid eighties at twenty-five years, a tunnel oxide module in the upper eighties, and a heterojunction or glass-glass module near ninety, so that field carries no default either. {note}
+
+### The module warranties shall be registered in the Owner's name, shall be transferable to a subsequent owner of the building, and shall not be conditioned on a maintenance more frequent than an annual inspection and a cleaning when soiling is observed.
+
+## Inverter, Electronics, and Racking Warranties {toc}
+
+### The inverter manufacturer shall warrant the inverters and the module-level electronics against defects in materials and workmanship for not less than the term indicated in the datasheet, with the coverage indicated in the datasheet.
+
```datasheet
−label: Installation Workmanship Warranty
+label: Inverter Warranty Term
type: range
−unit: yr
−min: 1
−max: 10
−step: 1
−default: 5
+unit: years
+options:
+ min: 5
+ max: 25
+ step: 1
+constraint: min
```
−## The module power performance warranty shall state the guaranteed percentage of nameplate power retained at the end of the warranty term.
+```datasheet
+label: Inverter Warranty Coverage
+type: radio
+options:
+ - "Parts"
+ - "Parts and on-site labor"
+```
−## The roofing warranty shall remain intact; the PV installation workmanship warranty shall not be construed to cover roof leaks arising from penetrations, which remain the responsibility of the party that performed the roof work under the roofing manufacturer's approved details.
+### String inverters are sold with five or ten years and an extension to fifteen or twenty for a price, microinverters and optimizers with twenty-five years to match the modules, and central inverters with five years and a service contract, so the term follows the architecture and the field carries no default; a parts warranty ships the replacement and leaves the Owner to pay the technician, which suits an Owner with a maintenance contract, and a parts and labor warranty brings the manufacturer to the roof, which suits an Owner with no one trained on the equipment. Neither coverage is the norm, so that field carries no default. {note}
−# Spare Parts {toc}
+### The racking manufacturer shall warrant the racking, its finish, and its bonding components against defects and against corrosion for not less than the term indicated in the datasheet.
−## The Contractor shall provide spare parts as scheduled below to support post-acceptance maintenance.
+```datasheet
+label: Racking Warranty Term
+type: range
+unit: years
+options:
+ min: 10
+ max: 25
+ step: 1
+constraint: min
+```
−- Spare PV modules of each type installed
−- Spare DC connectors of each type installed
−- Spare DC source-circuit fuses of each rating installed
+## Installation Warranty {toc}
+### The Contractor shall warrant the installation, including every termination, connector, attachment, flashing by the photovoltaic work, and the results of the commissioning tests, for not less than the term indicated in the datasheet, and shall correct a defect in it, including a roof leak at a photovoltaic attachment, at no cost to the Owner.
+
```datasheet
−label: Spare Modules Provided
+label: Installation Warranty Term
type: range
−unit: ea
−min: 0
−max: 20
−step: 1
−default: 2
+unit: years
+options:
+ min: 1
+ max: 10
+ step: 1
+constraint: min
```
+### A component or a module replaced under warranty shall be warranted for the remainder of the original term or for one year from the date of replacement, whichever ends later, and a replacement module shall be matched in electrical characteristics to the string it joins as the manufacturer's instructions require.
+
+### The roofing warranty shall remain in force with the array installed, and where a roof leak occurs at a photovoltaic attachment, the Contractor shall bear the cost of the investigation and the repair unless the roofing contractor's work under its own details is shown to be the cause.
+
+## Production Guarantee {toc}
+
+### The production guarantee carried by the Contractor shall be as indicated in the datasheet.
+
```datasheet
−label: Required Spare Parts
+label: Production Guarantee
+type: radio
+options:
+ - "No production guarantee beyond the equipment warranties"
+ - "Energy production guarantee by the Contractor for the term and the percentage indicated"
+```
+
+### A production guarantee makes the Contractor answer for the energy the model promised, settled annually against the revenue-grade meter and the measured weather, and it is the instrument a financed system, a power purchase agreement, or an Owner who bought on a payback requires; without one the Owner holds the equipment warranties and the energy model as a prediction. Whether one is carried follows how the system is financed, so the field carries no default, and a guarantee cannot be settled without the production meter and the irradiance and temperature instruments selected under this standard. {note}
+
+### Where a production guarantee is selected, the guaranteed annual energy shall be not less than the percentage of the modeled annual production indicated in the datasheet, weather-corrected under IEC 61724-3, for the term indicated in the datasheet, and the shortfall shall be settled as the Contract provides.
+
+```datasheet
+label: Production Guarantee Term
+type: range
+unit: years
+options:
+ min: 1
+ max: 10
+ step: 1
+constraint: exact
+```
+
+```datasheet
+label: Guaranteed Annual Energy as a Percentage of Modeled Production
+type: range
+unit: '%'
+options:
+ min: 80
+ max: 100
+ step: 1
+constraint: min
+```
+
+### The modeled figure is a fifty percent probability of exceedance, so a guarantee at 100 percent of it is missed half the time by a perfect system; guarantees are written at 90 to 95 percent of the model for the uncertainty of the weather correction, the soiling, and the availability, and over terms of two to five years in construction contracts and up to the financing term in a power purchase agreement. Both values follow the financing, so neither field carries a default. {note}
+
+# Spare Parts {toc}
+
+## The spare part types to be delivered with the system shall be as indicated in the datasheet.
+
+```datasheet
+label: Spare Part Types
type: checkbox
options:
− - "Spare PV modules (each type)"
− - "Spare DC connectors (each type)"
− - "Spare DC source-circuit fuses (each rating)"
−default: ["Spare DC connectors (each type)", "Spare DC source-circuit fuses (each rating)"]
+ - "Modules of the model installed"
+ - "DC connectors of the series installed, with the crimp tool and die"
+ - "Photovoltaic fuses of each rating installed"
+ - "Module-level electronic devices or rapid shutdown devices of each type installed"
+ - "Racking clamps, bonding components, and ground lugs"
+ - "Inverter fans, filters, and surge protective device modules"
+ - "Monitoring gateway and sensors"
+default:
+ - "DC connectors of the series installed, with the crimp tool and die"
+ - "Photovoltaic fuses of each rating installed"
+constraint: all_of
```
−## Spare modules shall be from the same make and model as the installed array so that replacements match the electrical characteristics of the source circuit.
+## The number of spare modules shall be as indicated in the datasheet, as a percentage of the installed module count, rounded up to a whole module.
+
+```datasheet
+label: Spare Modules
+type: range
+unit: '% of installed modules'
+options:
+ min: 0
+ max: 5
+ setpoints: [0, 0.5, 1, 2, 5]
+constraint: exact
+```
+
+## A module model is in production for two or three years and a replacement bought later is a different module, with a different voltage and current that mismatch the string and a different frame that often does not fit the clamps, which is why spares of the installed model are bought with the array; one percent covers the breakage of a decade on most arrays, and a zero records that the Owner accepts a mismatched replacement or a reconfigured string. The connectors and the fuses are the spares that are used, and the crimp tool is what keeps a replacement connector in the listed series. No quantity is the norm, so the field carries no default. {note}
+
+## Spare modules shall be stored by the Owner in the manufacturer's packaging, on edge, indoors, and the Contractor shall deliver them with a written storage instruction and obtain a signed receipt.
+
+## Spare parts shall be identical to and interchangeable with the installed parts, shall be the parts the manufacturers list for the system, and shall be delivered in their original packaging and labeled with the equipment they serve.