+---
+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/dc-battery-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.
+---
+
+# Scope {toc}
+
+## This standard covers the materials, ratings, configuration, mounting, installation, and testing of grid-interconnected photovoltaic (PV) electric power systems for buildings. {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 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}
+
+## 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.
+
+## PV systems shall comply with the edition of NFPA 70 adopted by the Authority Having Jurisdiction (AHJ).
+
+## 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}
+
+## 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.
+
+## The Contractor shall coordinate the DC and AC conductors and their overcurrent protection with [[sync/conductors-and-cables]] and [[sync/raceways-and-conduit]].
+
+## The Contractor shall coordinate the equipment grounding and bonding with [[sync/grounding-and-bonding]].
+
+## The Contractor shall coordinate the DC and AC surge protective devices with [[sync/surge-protective-devices]].
+
+## 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/dc-battery-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.
+
+| 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 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 |
+| 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 |
+| ANSI/NETA ATS | Standard for Acceptance Testing Specifications for Electrical Power Equipment and Systems |
+
+## 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 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:
+
+- 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
+
+```datasheet
+label: Action Submittals Required
+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"]
+```
+
+### Installation of any PV equipment shall not proceed until the corresponding submittals are 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. {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}
+
+## Closeout Submittals {toc}
+
+### The Contractor shall provide the following at substantial completion before the PV work 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
+
+```datasheet
+label: Required 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"
+ - "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"]
+```
+
+# Quality Assurance {toc}
+
+## Listing and Labeling {toc}
+
+### PV modules shall be listed and labeled to UL 61730 by a Nationally Recognized Testing Laboratory.
+
+### 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, converters, and interconnection system equipment shall be listed and labeled to UL 1741 with the supplement required by the serving utility.
+
+### Racking and mounting systems shall be listed and labeled to UL 2703.
+
+### A listed PV hazard control system, where used to meet rapid shutdown, shall be listed and labeled to UL 3741.
+
+### Equipment that is not listed and labeled as required by this standard shall not be installed. {note}
+
+## 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 electrical interconnection shall be performed by a licensed electrician working under a licensed electrical contractor.
+
+### 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}
+
+## Coordination {toc}
+
+### 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.
+
+### 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 arc-fault protection required by NEC 690.11 shall be verified compatible with the selected rapid-shutdown system and module-level electronics before procurement.
+
+### 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.
+
+### 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}
+
+# 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}
+
+### 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 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.
+
+### 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.
+
+```datasheet
+label: Design Wind Speed (Ultimate)
+type: range
+unit: mph
+min: 90
+max: 200
+step: 5
+default: 115
+```
+
+```datasheet
+label: Ground Snow Load
+type: range
+unit: psf
+min: 0
+max: 100
+step: 5
+default: 20
+```
+
+```datasheet
+label: Lowest Expected Ambient Temperature (for NEC 690.7 voltage)
+type: range
+unit: °C
+min: -40
+max: 10
+step: 1
+default: -20
+```
+
+### Modules and exposed equipment shall be rated for outdoor ultraviolet exposure and the full site temperature range over the system service life.
+
+## 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. {note}
+
+# PV Modules {toc}
+
+## Module Type and Rating {toc}
+
+### PV modules shall be new, of a single make and model within each array, and listed to UL 61730.
+
+### The module cell technology, nameplate power, and bifaciality shall be as scheduled below.
+
+```datasheet
+label: Module Cell Technology
+type: select
+options:
+ - "Monocrystalline PERC"
+ - "Monocrystalline TOPCon"
+ - "Monocrystalline heterojunction (HJT)"
+default: "Monocrystalline TOPCon"
+```
+
+```datasheet
+label: Module Configuration
+type: radio
+options:
+ - "Monofacial"
+ - "Bifacial (glass-glass)"
+default: "Monofacial"
+```
+
+```datasheet
+label: Module Nameplate Power (STC)
+type: range
+unit: W
+min: 350
+max: 700
+step: 5
+default: 550
+```
+
+```datasheet
+label: Module Frame
+type: radio
+options:
+ - "Anodized aluminum framed"
+ - "Frameless (glass-glass)"
+default: "Anodized aluminum framed"
+```
+
+### 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.
+
+### Modules within a single source circuit shall be electrically matched so that current mismatch does not impair string performance. {note}
+
+## Module Performance Basis {toc}
+
+### Modules should additionally be qualified to IEC 61215 for design qualification and type approval as a performance basis in addition to the UL listing.
+
+### 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. {note}
+
+# Inverters {toc}
+
+## Inverter Topology {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.
+
+```datasheet
+label: Inverter Topology
+type: select
+options:
+ - "String inverter"
+ - "String inverter with DC optimizers (MLPE)"
+ - "Microinverter (AC modules)"
+ - "Central / skid-mounted inverter"
+default: "String inverter"
+```
+
+### 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.
+
+### Inverters shall provide the grid-support, ride-through, and anti-islanding functions of IEEE 1547-2018 as configured for the utility interconnection agreement.
+
+### 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. {note}
+
+## Inverter Ratings {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 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. {note}
+
+```datasheet
+label: Maximum DC System Voltage
+type: radio
+unit: V
+options:
+ - "600"
+ - "1000"
+default: "1000"
+```
+
+```datasheet
+label: Inverter AC Output Configuration
+type: select
+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"
+```
+
+```datasheet
+label: Module-Level Power Electronics (MLPE)
+type: radio
+options:
+ - "None (string only)"
+ - "DC optimizers"
+ - "Microinverters"
+default: "None (string only)"
+```
+
+### Transformerless (non-isolated) inverters shall provide the DC ground-fault detection and interruption required by NEC 690.41 integral to the inverter.
+
+### Where a non-isolated inverter does not provide integral ground-fault protection, a separate listed ground-fault protection device shall be furnished. {note}
+
+# Rapid Shutdown and Arc-Fault Protection {toc}
+
+## Rapid Shutdown {toc}
+
+### The PV system shall include a rapid-shutdown function meeting NEC 690.12 for the adopted code edition.
+
+### The rapid-shutdown method shall be one of the approaches scheduled below.
+
+```datasheet
+label: Rapid-Shutdown Method
+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)"
+```
+
+### Module-level rapid shutdown shall reduce controlled conductors within the array boundary to not more than 1 V within 30 seconds of initiation.
+
+### 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.
+
+### 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. {note}
+
+### A rapid-shutdown initiation device shall be provided at a location accessible to first responders.
+
+### The rapid-shutdown initiator shall be marked with the label required by NEC 690.56(C).
+
+### 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. {note}
+
+```datasheet
+label: Rapid-Shutdown Initiator Location
+type: select
+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"
+```
+
+## Arc-Fault Protection {toc}
+
+### PV DC source and output circuits shall be provided with arc-fault protection meeting NEC 690.11.
+
+### The arc-fault protection function shall be verified to operate correctly with the selected module-level electronics and rapid-shutdown system. {note}
+
+# Conductors, Connectors, and Overcurrent Protection {toc}
+
+## DC Circuits {toc}
+
+### 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.
+
+### Exposed single-conductor DC PV wire shall be listed PV wire or photovoltaic cable suitable for wet locations and sunlight resistance.
+
+### 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.
+
+### 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. {note}
+
+### 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.
+
+### 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]].
+
+## AC Circuits {toc}
+
+### Inverter output (AC) circuits shall be sized to 125% of the continuous inverter output current.
+
+### 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.
+
+### The point of interconnection shall be shown on the drawings [[drawing: interconnection point]].
+
+# Grounding and Bonding {toc}
+
+## Equipment Grounding {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.
+
+### 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.
+
+### 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}
+
+```datasheet
+label: Module / Racking Bonding Method
+type: radio
+options:
+ - "UL 2703 integrated bonding (listed bonding components)"
+ - "Separate equipment grounding conductor (EGC)"
+default: "UL 2703 integrated bonding (listed bonding components)"
+```
+
+### The equipment grounding conductor shall be sized per NEC 690.45 and 250.122 for the overcurrent device protecting the circuit.
+
+### The PV array grounding shall be connected to the building grounding electrode system and coordinated with [[sync/grounding-and-bonding]].
+
+## Ground-Fault Protection {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.
+
+### 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}
+
+# Surge Protection {toc}
+
+## 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}
+
+### 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.
+
+### DC surge protective devices shall be listed for DC PV use and rated for the maximum PV system voltage.
+
+### Surge protective devices shall be coordinated with [[sync/surge-protective-devices]].
+
+```datasheet
+label: DC Surge Protective Device Type
+type: radio
+options:
+ - "Type 1 (line side, lightning-exposed)"
+ - "Type 2 (load side of disconnect)"
+default: "Type 2 (load side of disconnect)"
+```
+
+```datasheet
+label: AC Surge Protective Device Type
+type: radio
+options:
+ - "Type 1 (service entrance)"
+ - "Type 2 (inverter output / panel)"
+default: "Type 2 (inverter output / panel)"
+```
+
+### Where the building has a lightning protection system, the PV surge and bonding provisions shall be coordinated with it per [[sync/lightning-protection]]. {note}
+
+# Mounting and Racking {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.
+
+```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)"
+```
+
+### Racking shall be listed to UL 2703 and installed within the limits of its listing for tilt, span, and clamping.
+
+### The array layout shall not be finalized until the roof or foundation structural capacity is confirmed in writing by a licensed structural engineer.
+
+### 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. {note}
+
+## Ballasted Roof Mounting {toc}
+
+### 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.
+
+```datasheet
+label: Ballasted Array Distributed Dead Load
+type: range
+unit: psf
+min: 3
+max: 6
+step: 0.5
+default: 4
+```
+
+### The ballasted system shall include a slip sheet or protection layer compatible with the roof membrane to prevent abrasion of the roofing.
+
+### 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. {note}
+
+## Attached and Penetrating Mounting {toc}
+
+### Roof penetrations shall be flashed and sealed using assemblies approved by the roofing manufacturer.
+
+### The roof penetration details and the roofing manufacturer's approval shall be coordinated to preserve the existing roof warranty.
+
+### 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. {note}
+
+### The penetration attachment pattern and locations shall be shown on the drawings [[drawing: roof attachment layout]].
+
+## Standing-Seam Metal Roof Mounting {toc}
+
+### Clamps for standing-seam metal roofs shall be listed for the specific seam profile and shall not penetrate the roof panel.
+
+### Standing-seam clamp loads shall be coordinated with the metal roof manufacturer to confirm the seam and panel can carry the clamp reactions. {note}
+
+## Ground-Mount Foundations {toc}
+
+### Ground-mount foundations shall be designed by a licensed engineer using a project geotechnical report.
+
+```datasheet
+label: Ground-Mount Foundation Type
+type: select
+options:
+ - "Driven steel pile"
+ - "Helical screw pile"
+ - "Ballasted concrete (non-penetrating)"
+ - "Cast-in-place concrete pier"
+default: "Driven steel pile"
+```
+
+### 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}
+
+### 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}
+
+# Fire-Service Access {toc}
+
+## 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}
+
+### A clear ridge setback shall be maintained along the roof ridge as required by the adopted fire code.
+
+### Perimeter access pathways shall be maintained around the array as required by the adopted fire code.
+
+### Mid-array access aisles shall be provided for arrays exceeding the area threshold of the adopted fire code.
+
+```datasheet
+label: Ridge / Perimeter Setback Width
+type: range
+unit: in
+min: 18
+max: 48
+step: 6
+default: 36
+```
+
+### 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. {note}
+
+### The rooftop fire-service access layout shall be shown on the drawings [[drawing: fire access pathway plan]].
+
+# 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 meter shall meet ANSI C12.20 accuracy class as scheduled below.
+
+```datasheet
+label: Production Meter Accuracy Class
+type: radio
+options:
+ - "ANSI C12.20 Class 0.5"
+ - "ANSI C12.20 Class 0.2"
+default: "ANSI C12.20 Class 0.5"
+```
+
+### 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}
+
+## Monitoring {toc}
+
+### A monitoring system shall report system production, inverter status, and fault alarms.
+
+### Module-level monitoring shall be provided where DC optimizers or microinverters are used, to report per-module performance.
+
+```datasheet
+label: Monitoring Granularity
+type: radio
+options:
+ - "System-level (inverter)"
+ - "String-level"
+ - "Module-level (MLPE)"
+default: "System-level (inverter)"
+```
+
+# Interconnection {toc}
+
+## The PV system shall interconnect with the building electrical system by one of the paths scheduled below, in accordance with NFPA 70 Article 705. {note}
+
+```datasheet
+label: Interconnection Path
+type: radio
+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)"
+```
+
+### 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 supply-side connection shall be made ahead of the service disconnecting means in accordance with NEC 705.11.
+
+### The interconnection shall not be energized until the serving utility grants permission to operate following any required witness test. {note}
+
+### The point of interconnection and the backfeed overcurrent device shall be coordinated with the existing distribution equipment per [[sync/low-voltage-panelboards]].
+
+# Energy Storage Interface {toc}
+
+## 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 PV-to-storage coupling method, where storage is provided, shall be documented and coordinated with [[sync/dc-battery-systems]].
+
+### 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. {note}
+
+# Labeling {toc}
+
+## 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.
+
+## Labels shall be permanent, weather-resistant, and legible for the system service life.
+
+## Field labeling shall be coordinated with [[sync/equipment-labeling]].
+
+```datasheet
+label: Required PV Field Labels
+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)"]
+```
+
+# Testing {toc}
+
+## Acceptance Testing {toc}
+
+### The PV system shall be commissioned and acceptance-tested before energization in accordance with ANSI/NETA ATS and the manufacturer's commissioning procedures.
+
+### Each PV source circuit shall be tested for correct polarity, open-circuit voltage, and operating current, and the readings shall be recorded.
+
+### DC and AC conductor insulation resistance shall be tested and recorded prior to energization.
+
+### The rapid-shutdown function shall be tested to confirm the controlled conductors reach the required voltage within 30 seconds of initiation.
+
+### The ground-fault and arc-fault protection functions shall be tested to confirm correct operation.
+
+### The anti-islanding function shall be confirmed by the utility witness test or by the inverter listing where a witness test is waived. {note}
+
+```datasheet
+label: Required Acceptance Tests
+type: checkbox
+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"]
+```
+
+### Any test result outside the acceptance criteria shall be corrected and retested before the system is placed in service. {note}
+
+# 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 not be lifted, carried, or set down by their junction boxes, cables, or connectors.
+
+## Inverters and electronic equipment shall be stored within the manufacturer's temperature and humidity limits and protected from construction dust and moisture. {note}
+
+## Modules shall not be stepped on or stacked beyond the manufacturer's permitted stacking height, because mechanical microcracking degrades output without visible damage. {note}
+
+# Warranty {toc}
+
+## The Contractor shall provide the manufacturer's product warranties for modules, inverters, and racking, and an installation workmanship warranty.
+
+```datasheet
+label: Module Product Warranty
+type: range
+unit: yr
+min: 10
+max: 25
+step: 1
+default: 12
+```
+
+```datasheet
+label: Module Power Performance Warranty
+type: range
+unit: yr
+min: 20
+max: 30
+step: 1
+default: 25
+```
+
+```datasheet
+label: Inverter Warranty
+type: range
+unit: yr
+min: 5
+max: 25
+step: 1
+default: 10
+```
+
+```datasheet
+label: Installation Workmanship Warranty
+type: range
+unit: yr
+min: 1
+max: 10
+step: 1
+default: 5
+```
+
+## The module power performance warranty shall state the guaranteed percentage of nameplate power retained at the end of the warranty term. {note}
+
+## 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. {note}
+
+# Spare Parts {toc}
+
+## The Contractor shall provide spare parts as scheduled below to support post-acceptance maintenance.
+
+- Spare PV modules of each type installed
+- Spare DC connectors of each type installed
+- Spare DC source-circuit fuses of each rating installed
+
+```datasheet
+label: Spare Modules Provided
+type: range
+unit: ea
+min: 0
+max: 20
+step: 1
+default: 2
+```
+
+```datasheet
+label: Required Spare Parts
+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)"]
+```
+
+## 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. {note}