SYNC™

SynC · Historical revision

Battery Energy Storage Systems

Revision3
EditedOct 17, 2026
StatusSuperseded
Contents

View changes in this revision   Revision history

Historical revision. This is editorial revision 3, kept so citations to it stay resolvable. It is not the current text of this standard — see the current revision.

SynC Standards Team — Specifier (Platform Standards) ✓ OfficialDiscloses employment SynC (SynC Platform Team)
Rewritten as the owner of stationary energy storage under UL 9540, UL 9540A, NFPA 855 and IFC 1207: chemistry and use case as independent decisions, separation and hazard mitigation derived, and the DC station-battery and UPS standards now point here.

1 Scope

NOTE This standard governs the stationary battery energy storage system as a listed assembly and the work that puts it into service: the battery modules and racks or cabinets, the battery management system, the power conversion system, the site controller, the thermal management, the enclosure or the room it occupies, the fire and gas detection, the suppression and explosion control integral to the installation, the emergency shutdown, the separation from exposures, the hazard mitigation analysis and the emergency response plan, the capacity test, and the plan for its removal at end of life. (1.1)
NOTE An energy storage system is governed by two code families at once: NFPA 70 Articles 705 and 706 decide how it connects to the premises wiring and the utility, and NFPA 855 with the adopted fire code decide where it may sit, how much energy may be gathered in one place, and what detects, contains, and vents a cell failure. The UL 9540 listing proves the assembly as built; the UL 9540A test data prove how a failure in it behaves, and most of the fire-safety decisions in this standard are read off that data rather than chosen. (1.2)
NOTE The chemistry, the installation location, the enclosure form, the application, the coupling to on-site generation, and the grid interaction are independent decisions and are carried as independent selections in this standard; every combination is manufactured, and this standard does not assume that one selection implies another. (1.3)
NOTE The usable energy, the rated power, the point of interconnection, and the voltage at that point are project-sized values that live on the one-line diagram and the equipment schedules; the datasheet of this standard records them where one value applies to the whole system and otherwise points at those documents. (1.4)
NOTE The following are governed elsewhere and are outside this standard: (1.5)
  • the station battery and charger that supply switchgear control power, telecommunications, or SCADA, under DC Battery SystemsDC Battery SystemsResolves to the current adopted revision.sync/dc-battery-systems
  • the uninterruptible power supply and its internal battery, which carry a critical load through an interruption as one listed product, under Uninterruptible Power Supply SystemsUninterruptible Power Supply SystemsResolves to the current adopted revision.sync/uninterruptible-power-supply-systems
  • the photovoltaic array, its modules, string and central inverters, combiners, array DC wiring, and rapid shutdown, under Photovoltaic SystemsPhotovoltaic SystemsResolves to the current adopted revision.sync/photovoltaic-systems
  • the classification of loads, the selection of the alternate source, and the transfer scheme of the emergency and standby power system, under Emergency And Standby PowerEmergency and Standby Power SystemsResolves to the current adopted revision.sync/emergency-and-standby-power
  • the engine-generator set under GeneratorsEngine GeneratorsResolves to the current adopted revision.sync/generators, the automatic transfer switch under Automatic Transfer SwitchesAutomatic Transfer SwitchesResolves to the current adopted revision.sync/automatic-transfer-switches, and paralleling switchgear under Generator Paralleling SwitchgearGenerator Paralleling SwitchgearResolves to the current adopted revision.sync/generator-paralleling-switchgear
  • the fire alarm control unit, its initiating devices and notification appliances, and its transmission to the supervising station, under Fire Alarm SystemsFire Alarm SystemsResolves to the current adopted revision.sync/fire-alarm-systems
  • the sprinkler system that protects the room or the building, under Wet Pipe Fire Sprinkler SystemsWet-Pipe Fire Sprinkler SystemsResolves to the current adopted revision.sync/wet-pipe-fire-sprinkler-systems, and a clean agent system installed to flood a room as a building system, under Clean Agent Fire SuppressionClean Agent Fire Suppression SystemsResolves to the current adopted revision.sync/clean-agent-fire-suppression
  • gas detection in parking garages, refrigerant machinery rooms, and other occupied building spaces, under Gas Detection SystemsGas Detection SystemsResolves to the current adopted revision.sync/gas-detection-systems
  • the grounding electrode system and the equipment grounding conductors, under Grounding And BondingGrounding and Bonding for Electrical SystemsResolves to the current adopted revision.sync/grounding-and-bonding
  • the feeders, the field-installed DC conductors, and the raceways that carry them, under Conductors And CablesConductors and CablesResolves to the current adopted revision.sync/conductors-and-cables and Raceways And ConduitRaceways and ConduitResolves to the current adopted revision.sync/raceways-and-conduit
  • the switchboard, switchgear, or panelboard at the point of interconnection, under Low Voltage SwitchboardsLow Voltage SwitchboardsResolves to the current adopted revision.sync/low-voltage-switchboards, Low Voltage SwitchgearLow Voltage SwitchgearResolves to the current adopted revision.sync/low-voltage-switchgear, Medium Voltage SwitchgearMedium Voltage SwitchgearResolves to the current adopted revision.sync/medium-voltage-switchgear, and PanelboardsPanelboardsResolves to the current adopted revision.sync/panelboards, and the step-up transformer under Medium Voltage TransformersMedium-Voltage Distribution TransformersResolves to the current adopted revision.sync/medium-voltage-transformers
  • the utility service, its capacity, and its upgrade, under Electrical Service EntranceElectrical Service EntranceResolves to the current adopted revision.sync/electrical-service-entrance
  • the enclosed switch furnished where a separate disconnecting means is required, under Enclosed Switches And DisconnectsEnclosed Switches and DisconnectsResolves to the current adopted revision.sync/enclosed-switches-and-disconnects
  • the short-circuit, coordination, and arc-flash studies that take the fault contribution of the system as an input, under Short Circuit StudyShort-Circuit StudyResolves to the current adopted revision.sync/short-circuit-study, Protective Coordination StudyProtective Device Coordination StudyResolves to the current adopted revision.sync/protective-coordination-study, and Arc Flash StudyArc-Flash StudyResolves to the current adopted revision.sync/arc-flash-study
  • the surge protective device as a product, under Surge Protective DevicesSurge Protective DevicesResolves to the current adopted revision.sync/surge-protective-devices, and the lightning protection system, under Lightning ProtectionLightning Protection SystemsResolves to the current adopted revision.sync/lightning-protection
  • the material, lettering, and attachment of nameplates, labels, and placards, under Electrical IdentificationWiring System IdentificationResolves to the current adopted revision.sync/electrical-identification
  • the revenue and submetering instruments, under Electrical Power MonitoringElectrical Power Monitoring and MeteringResolves to the current adopted revision.sync/electrical-power-monitoring
  • the building automation system that reads the storage data, under Building Automation SystemBuilding Automation SystemResolves to the current adopted revision.sync/building-automation-system, and the network cabling, under Structured CablingStructured Cabling SystemsResolves to the current adopted revision.sync/structured-cabling
  • the concrete pad under an outdoor unit, under Concrete PadsConcrete Equipment PadsResolves to the current adopted revision.sync/concrete-pads
  • the rated walls and floors of a battery room, under Fire Rated Wall And Floor AssembliesFire-Resistance-Rated AssembliesResolves to the current adopted revision.sync/fire-rated-wall-and-floor-assemblies, the seals at its penetrations, under FirestoppingFirestoppingResolves to the current adopted revision.sync/firestopping, and the room itself, under Electrical RoomsElectrical RoomsResolves to the current adopted revision.sync/electrical-rooms
  • bollards, under Site Furnishings And BollardsSite Furnishings and BollardsResolves to the current adopted revision.sync/site-furnishings-and-bollards, and security fencing, under Fencing And GatesFencing and GatesResolves to the current adopted revision.sync/fencing-and-gates
  • electric vehicle charging equipment, including a charger with an integral battery, under Electric Vehicle ChargingElectric Vehicle Charging EquipmentResolves to the current adopted revision.sync/electric-vehicle-charging
NOTE Microgrid and economic-dispatch controllers that command more than one source, transmission-connected storage operated under an ISO or RTO agreement, mobile and portable storage, flywheel, thermal, compressed-air, and hydrogen storage, and vehicle traction batteries, including second-life packs that carry no UL 1973 listing, are outside this standard and are not governed by another standard in this library. (1.6)
1.7 The energy storage system shall comply with NFPA 70 Articles 705 and 706, with NFPA 855, and with the energy storage provisions of the adopted fire code, and shall be listed and labeled to UL 9540 by a Nationally Recognized Testing Laboratory as one system.
1.8 The location of the system and of each of its units shall be as indicated on the electrical site plan.
1.9 Where a value stated on the one-line diagram or the equipment schedules for the system differs from the datasheet selection under this standard, the drawing shall govern for that system.

2 Referenced Standards

2.1 Equipment, materials, and installation shall comply with the latest adopted edition of each of the following unless a specific edition is cited.
2.2 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 (Articles 110, 250, 480, 490, 705, 706, and 710)
NFPA 70E Standard for Electrical Safety in the Workplace
NFPA 855 Standard for the Installation of Stationary Energy Storage Systems
NFPA 1 Fire Code (Chapter 52, Energy Storage Systems)
IFC International Fire Code (Section 1207, Electrical Energy Storage Systems)
NFPA 72 National Fire Alarm and Signaling Code
NFPA 13 Standard for the Installation of Sprinkler Systems
NFPA 68 Standard on Explosion Protection by Deflagration Venting
NFPA 69 Standard on Explosion Prevention Systems
NFPA 750 Standard on Water Mist Fire Protection Systems
NFPA 2001 Standard on Clean Agent Fire Extinguishing Systems
NFPA 704 Standard System for the Identification of the Hazards of Materials for Emergency Response
UL 9540 Energy Storage Systems and Equipment
UL 9540A Test Method for Evaluating Thermal Runaway Fire Propagation in Battery Energy Storage Systems
UL 1973 Batteries for Use in Stationary and Motive Auxiliary Power Applications
UL 1642 Lithium Batteries
UL 1741 Inverters, Converters, Controllers and Interconnection System Equipment for Use With Distributed Energy Resources (including Supplement SB)
UL 3141 Power Control Systems
UL 2775 Fixed Condensed Aerosol Extinguishing System Units
UL 50E Enclosures for Electrical Equipment, Environmental Considerations
NEMA 250 Enclosures for Electrical Equipment (1000 Volts Maximum)
IEEE 1547 Standard for Interconnection and Interoperability of Distributed Energy Resources with Associated Electric Power Systems Interfaces
IEEE 1547.1 Standard Conformance Test Procedures for Equipment Interconnecting Distributed Energy Resources with Electric Power Systems and Associated Interfaces
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
IEEE 2686 Recommended Practice for Battery Management Systems in Energy Storage Applications
IEEE 519 Standard for Harmonic Control in Electric Power Systems
IEEE 1635 / ASHRAE 21 Guide for the Ventilation and Thermal Management of Batteries for Stationary Applications
IEEE 1188 Recommended Practice for Maintenance, Testing, and Replacement of Valve-Regulated Lead-Acid (VRLA) Batteries for Stationary Applications
ASHRAE 15 Safety Standard for Refrigeration Systems
ASCE/SEI 7 Minimum Design Loads and Associated Criteria for Buildings and Other Structures
IBC International Building Code
ANSI/NETA ATS Standard for Acceptance Testing Specifications for Electrical Power Equipment and Systems
UN Manual of Tests and Criteria Section 38.3, Lithium Metal and Lithium Ion Batteries
49 CFR Part 173 Shippers: General Requirements for Shipments and Packagings (Section 173.185, Lithium Cells and Batteries)
NOTE The SunSpec Modbus information model is published by an industry alliance rather than a standards body; it is cited because IEEE 1547 names it as one of the three interoperability interfaces a distributed energy resource may carry, and the serving utility's interconnection requirements decide which of the three a project needs. (2.3)

3 Submittals

3.1 Action Submittals

3.1.1 The Contractor shall submit the following for review before the energy storage system is released for manufacture:
  • product data for the battery modules, racks or cabinets, the battery management system, the power conversion system, the site controller, the thermal management equipment, and the enclosure, identifying the manufacturer, the catalog designation, the chemistry, the cell and module construction, the nameplate and usable energy, the rated charge and discharge power, the round-trip efficiency at rated power, the auxiliary power consumption, the operating temperature range, and the enclosure type
  • the UL 9540 listing of the system as a whole, and the UL 1973 listing of the battery and the UL 1741 listing of the power conversion system as its constituents
  • the UL 9540A test report for the cell, module, and unit furnished, and the installation-level report where this standard requires one, together with the manufacturer's statement of how the separation distances, the explosion control, and the suppression furnished follow from that report
  • shop drawings showing the arrangement of the units, the separation between units and to every exposure, the working space, the egress from a walk-in enclosure or a room, the raceway entries, the location of every disconnecting means and emergency shutdown control, and the location of the fire and gas detection, suppression, and explosion control devices
  • the one-line diagram of the system showing the battery strings, the DC and AC disconnecting means, the overcurrent protection, the power conversion system, the point of interconnection, the metering, and the grounding
  • the power conversion system settings record, including the IEEE 1547 normal and abnormal performance categories, the voltage and frequency trip and ride-through settings, the grid-support function settings, the export limit, and the anti-islanding method
  • the fire and gas detection, suppression, and explosion control design, including the NFPA 68 or NFPA 69 calculations where explosion control is furnished and the agent quantity and discharge design where an agent system is furnished
  • the thermal management calculation showing the heat rejected at rated power at Site Ambient Temperature MaximumSite Ambient Temperature MaximumParameterEach project supplies its own value.site-ambient-temperature-maximum and the heating furnished at Site Ambient Temperature MinimumSite Ambient Temperature MinimumParameterEach project supplies its own value.site-ambient-temperature-minimum
  • the seismic anchorage calculations and details for the units and the enclosure, sealed by an engineer licensed in the state of the project
  • the hazard mitigation analysis, where this standard requires one
  • the communications and cybersecurity provisions of the battery management system, the site controller, and the power conversion system
Action Submittalscheckbox
☑ Product data for every system component
☑ UL 9540, UL 1973, and UL 1741 listings
☑ UL 9540A test report and the derivations drawn from it
☑ Arrangement and separation shop drawings
☑ System one-line diagram
☑ Power conversion system settings record
☑ Fire, gas, suppression, and explosion control design
☑ Thermal management calculation
☑ Seismic anchorage calculations and details
☐ Hazard mitigation analysis
☑ Communications and cybersecurity provisions
3.1.2 The energy storage system shall not be released for manufacture until the product data, the listings, the UL 9540A test report, and the arrangement shop drawings have been reviewed and returned.
NOTE The UL 9540A report is the submittal everything else depends on: the separation the arrangement drawing shows, the explosion control the fire design assumes, and the size of unit the fire code allows are all read from that report, and a report for a different cell, a different module, or a different enclosure proves none of them for the product proposed. (3.1.3)

3.2 Informational Submittals

3.2.1 The Contractor shall submit the following with or before the action submittals:
  • the qualifications of the manufacturer, the installing contractor, and the field service technicians, as Quality Assurance requires
  • the manufacturer's installation instructions, including the lifting, the anchorage, the torque values, the state of charge at delivery and in storage, the maximum storage time before a commissioning charge, and the working space the listing requires
  • the utility interconnection application and the correspondence on its status, including the performance categories and the export limit the serving utility has assigned
  • the commissioning plan required by NFPA 855, listing each test on each system component, the instrument to be used, the acceptance criterion, and the witnesses
  • the draft emergency response plan and the first-responder information required by NFPA 855 and the adopted fire code
  • the draft decommissioning plan required by NFPA 855
Informational Submittalscheckbox
☑ Manufacturer, installer, and technician qualifications
☑ Manufacturer's installation instructions
☑ Utility interconnection application and status
☑ Commissioning plan
☑ Draft emergency response plan
☑ Draft decommissioning plan

3.3 Closeout Submittals

3.3.1 The Contractor shall submit the following before the energy storage system is accepted:
  • the factory acceptance test report
  • the field acceptance test and commissioning report, including the capacity test record, the result of every test in the commissioning plan, and the correction of every failure
  • the record drawings showing the installed arrangement, the separation distances as built, every disconnecting means and emergency shutdown control, the point of interconnection, and the raceway routing
  • the settings as left for the power conversion system, the battery management system, the site controller, and the gas detection
  • the utility's permission to operate and the executed interconnection agreement
  • the final emergency response plan, the first-responder information, and the record of the first-responder orientation this standard requires
  • the final decommissioning plan
  • the operation and maintenance data for every system component, including the manufacturer's maintenance schedule for the warranty term
  • the warranty documentation, including the performance guarantee, registered in the Owner's name
  • the administrator credentials for the site controller and the monitoring portal, transferred to the Owner
  • a signed receipt from the Owner for the spare parts delivered
Closeout Submittalscheckbox
☑ Factory acceptance test report
☑ Field acceptance test and commissioning report with the capacity test record
☑ Record drawings
☑ Settings as left
☑ Permission to operate and interconnection agreement
☑ Final emergency response plan and first-responder orientation record
☑ Final decommissioning plan
☑ Operation and maintenance data
☑ Warranty and performance guarantee documentation
☑ Controller and portal credentials transferred
☐ Spare parts receipt
NOTE The emergency response plan is a closeout document the fire department reads before it ever enters the site, and the decommissioning plan is the one the Owner reads a decade later; NFPA 855 requires both to exist, and a project that treats them as paperwork hands the Owner a system nobody knows how to fight or remove. (3.3.2)

4 Quality Assurance

4.1 Listing and Test Data

4.1.1 The energy storage system shall be listed to UL 9540 as a complete system, including the battery, the battery management system, the power conversion system, the thermal management, and the enclosure as furnished, and a field-assembled combination of separately listed components shall not be accepted in place of the system listing.
4.1.2 The battery modules shall be listed to UL 1973, and lithium-ion cells shall have been evaluated to UL 1642 as part of that listing.
4.1.3 The power conversion system shall be listed to UL 1741, and where it operates in parallel with the utility it shall be listed to Supplement SB of UL 1741 as conforming to IEEE 1547 and tested to IEEE 1547.1.
4.1.4 A UL 9540A test report shall be furnished for the cell, the module, and the unit as proposed, and an installation-level test report shall be furnished where the unit-level results did not meet the criteria under which UL 9540A permits the testing to end at the unit level for the installation location selected.
4.1.5 The UL 9540A report shall be for the same cell, module construction, module arrangement, and enclosure as the product proposed, and a report for another configuration shall not be accepted.
NOTE UL 9540A is a sequence of tests rather than one: the cell test establishes whether and how a cell goes into thermal runaway and what gas it releases, the module test establishes whether that runaway propagates between cells, the unit test establishes whether it propagates between modules and what heat and gas leave the unit, and the installation test establishes what happens to neighboring units and walls. Testing ends at the level where the results show the failure contained, and the level reached decides which prescriptive requirements of NFPA 855 the installation may depart from. (4.1.6)
4.1.7 No system component shall be modified in the field in a manner that departs from the configuration under which it was listed, and a replacement module, battery management board, or power conversion module shall be the part the manufacturer lists for that system.

4.2 Manufacturer Qualifications

4.2.1 The manufacturer of the energy storage system shall have furnished systems of the chemistry and enclosure form proposed that have been in commercial operation in North America for not less than three years, and shall maintain a service organization able to reach the site within the response time the warranty states.
4.2.2 The manufacturer shall be the single point of responsibility for the system listing, the performance guarantee, and the coordination of the battery, the power conversion system, the site controller, and the thermal management, whether or not it manufactures every component.
NOTE A battery from one maker, an inverter from another, and a controller from a third is how most systems are built, and it works when one party holds the listing and the guarantee; it fails when a capacity shortfall becomes an argument among three vendors about whose component lost the energy, which is why the single point of responsibility is required and the listing of the system as a whole is the proof of it. (4.2.3)

4.3 Installer Qualifications

4.3.1 The energy storage system shall be installed by the installer indicated in the datasheet.
Installer Qualificationradio
● Licensed electrical contractor trained by the manufacturer on the system furnished
○ Licensed electrical contractor holding an energy storage installation certification accepted by the Authority Having Jurisdiction, trained by the manufacturer on the system furnished
○ Manufacturer's own installation crew, with the electrical connections by a licensed electrical contractor
NOTE A licensed electrical contractor trained by the manufacturer on the product is the installer on most projects and is the condition of nearly every warranty, which is why it is the default; a certification accepted by the Authority Having Jurisdiction is required by some states and incentive programs and is selected where one applies; the manufacturer's own crew sets the battery and commissions the system where the product is a walk-in container or a large cabinet lineup the manufacturer prefers to place itself, with the electrical contractor making the connections. (4.3.2)
4.3.3 Each technician who connects, energizes, or commissions the battery shall have completed the manufacturer's training for the system furnished and shall be qualified under NFPA 70E for work on the DC voltages present.
4.3.4 The field acceptance tests this standard names shall be performed by the testing firm qualified under Electrical Acceptance TestingElectrical Acceptance TestingResolves to the current adopted revision.sync/electrical-acceptance-testing, with the manufacturer's technician present for the tests that involve the battery management system and the capacity test.

4.4 Source Limitation

4.4.1 The limitation on the sources of the energy storage equipment shall be as indicated in the datasheet.
Source Limitationradio
○ Battery, power conversion system, and site controller from one manufacturer or one system integrator
○ Battery and power conversion system from separate manufacturers under one system integrator's UL 9540 listing
○ No source limitation beyond the single point of responsibility
NOTE One manufacturer or integrator for the whole system gives the Owner one listing, one portal, one guarantee, and one service contact, and it limits competition to the firms that offer complete systems; separate component makers under one integrator's listing opens the inverter and the battery to competition while the integrator still holds the listing and the guarantee; no limitation beyond the single point of responsibility lets the Contractor assemble the lowest-cost combination that any integrator will list. Which is wanted depends on the Owner's maintenance organization and the market at the time of bid, so the field carries no default. (4.4.2)

4.5 Regulatory Requirements

4.5.1 The installation shall comply with the editions of NFPA 70, NFPA 855, and the fire code adopted with Adopted Building CodeAdopted Building CodeParameterEach project supplies its own value.adopted-building-code and with the amendments of the Authority Having Jurisdiction.
4.5.2 The Contractor shall confirm in writing with the Authority Having Jurisdiction, before the action submittals, the edition of NFPA 855 in force, whether a hazard mitigation analysis is required, and whether the UL 9540A test data will be accepted as the basis for separation, unit size, and explosion control.
4.5.3 An interconnection agreement with the serving utility shall be executed, and the utility's permission to operate obtained, before the system is operated in parallel with the utility.
NOTE NFPA 855 and UL 9540A have each been revised more than once in the last few years and jurisdictions adopt them on different schedules, so the edition the Authority Having Jurisdiction enforces, not the latest published, decides the prescriptive limits, and a confirmation in writing before design is the only way to know which one applies. (4.5.4)

5 Environmental and Service Conditions

5.1 Enclosure Type

5.1.1 The enclosure type of the battery cabinets, the walk-in enclosure, and the power conversion system shall be as indicated in the datasheet.
Enclosure Type per NEMA 250select
Type 1
Type 12
Type 3R
Type 3RX
Type 4
Type 4X
NOTE This product departs from the Type 1 convention of indoor electrical equipment because the energy storage system on most building and campus projects stands outdoors in a factory-assembled cabinet or a walk-in enclosure, which is where NFPA 855 permits the most energy with the fewest building provisions and where the manufacturers build for; nearly every listed cabinet system carries a Type 3R enclosure from the factory, which is why it is the default. Type 1 is the rating of racks and cabinets inside a battery room, and Type 12 is selected for an indoor cabinet in a dusty industrial space; Type 3RX adds corrosion resistance for a coastal or industrial atmosphere; Type 4 is gasketed against hose-directed water and wind-driven rain and is selected where the enclosure is washed down or stands in an exposed location; Type 4X adds corrosion resistance to that and is the rating of a marine or chemical-plant site. (5.1.2)
5.1.3 The enclosure shall comply with UL 50E and NEMA 250 for the type selected, and the type shall be marked on the enclosure.
5.1.4 A unit installed outdoors or on a roof shall have an enclosure of Type 3R, Type 3RX, Type 4, or Type 4X.
5.1.5 A unit 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 an enclosure of Type 3RX or Type 4X.
5.1.6 A unit installed where it is subject to hose-directed water or wash-down shall have an enclosure of Type 4 or Type 4X.
5.1.7 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.
5.1.8 Raceway entries into a Type 3R, Type 3RX, Type 4, or Type 4X enclosure shall be made only with fittings listed for the enclosure type and only at the entry locations the manufacturer provides.

5.2 Ambient Temperature and Altitude

5.2.1 A unit installed outdoors, on a roof, or in an unconditioned space shall deliver its rated power and its usable energy across the range from Site Ambient Temperature MinimumSite Ambient Temperature MinimumParameterEach project supplies its own value.site-ambient-temperature-minimum to Site Ambient Temperature MaximumSite Ambient Temperature MaximumParameterEach project supplies its own value.site-ambient-temperature-maximum, with its own thermal management holding the cells within the manufacturer's warranted temperature range.
5.2.2 Where the power conversion system reduces its output above a stated ambient temperature, the manufacturer shall state the temperature and the reduced output in the product data, and the output at Site Ambient Temperature MaximumSite Ambient Temperature MaximumParameterEach project supplies its own value.site-ambient-temperature-maximum shall be not less than the rated power indicated for the system.
5.2.3 The power conversion system and the thermal management equipment shall be derated for AltitudeAltitudeParameterEach project supplies its own value.altitude in accordance with the manufacturer's published correction factors, and the derated ratings shall be stated in the product data.
5.2.4 Where Site Ambient Temperature MinimumSite Ambient Temperature MinimumParameterEach project supplies its own value.site-ambient-temperature-minimum is below the lowest temperature at which the manufacturer permits the cells to be charged, the unit shall include heating that brings the cells to the charging temperature before the system accepts a charge, and the heating shall be fed from the auxiliary supply the system carries through an outage.
NOTE A lithium-ion cell charged below freezing plates lithium on its anode and is damaged permanently, so a system in a cold climate either heats its cells before it charges or refuses the charge; the heater is what lets a system that sat through a winter outage recharge when the utility returns, which is why it is required to survive the outage with the system. (5.2.5)

5.3 Seismic Anchorage

5.3.1 The battery racks and cabinets, the walk-in enclosure, and the power conversion system shall be anchored in accordance with the seismic provisions of Adopted Building CodeAdopted Building CodeParameterEach project supplies its own value.adopted-building-code and ASCE/SEI 7 Chapter 13 for Seismic Design CategorySeismic Design CategoryParameterEach project supplies its own value.seismic-design-category, with the anchorage designed and sealed by an engineer licensed in the state of the project.
5.3.2 Where Seismic Design CategorySeismic Design CategoryParameterEach project supplies its own value.seismic-design-category requires special certification of active equipment, the battery management system, the power conversion system, and the thermal management equipment shall carry a special seismic certification by shake-table testing or experience data in accordance with ASCE/SEI 7, and the certification shall be included with the action submittals.
5.3.3 The anchorage of the racks within a battery room and of the modules within a cabinet shall be the anchorage the manufacturer evaluated under the UL 9540 listing, and a field-designed rack shall not be substituted for the listed one.

5.4 Flood and Site Exposure

5.4.1 A unit installed outdoors shall be set with the bottom of its enclosure and every ventilation and deflagration opening above the design flood elevation indicated on the civil site plan.
5.4.2 A unit installed outdoors shall withstand the wind and snow loads of Adopted Building CodeAdopted Building CodeParameterEach project supplies its own value.adopted-building-code for the site, and the enclosure manufacturer shall state the design wind speed and the roof snow load the enclosure was evaluated for in the product data.

6 Installation Location and Enclosure Form

6.1 Installation Location

6.1.1 The installation location of the energy storage system shall be as indicated in the datasheet.
Installation Locationradio
○ Indoors, in a dedicated-use building
○ Indoors, in a room of a building with other uses
○ Outdoors, ground-mounted
○ On a roof or in an open parking structure
Per drawings — the electrical site plan (deferred by default)
NOTE The location decides which chapter of NFPA 855 governs, and each chapter sets its own limits: a dedicated-use building houses the largest aggregate energy with the fewest exposures, a room in a building with other uses carries the lowest aggregate limit and the most construction, detection, and suppression provisions because people live and work on the other side of its walls, an outdoor ground-mounted installation trades building provisions for separation distances and fire department access, and a roof or an open parking structure carries the outdoor provisions plus the structural, fire-service access, and exposure provisions of being on top of or inside an occupied building. The location is set by the site and the building, which is why it is stated on the electrical site plan. (6.1.2)
6.1.3 An indoor installation in a room of a building with other uses shall be in a room separated from the rest of the building by fire barriers and horizontal assemblies of the rating NFPA 855 and the adopted fire code require for the chemistry and energy installed, constructed under Fire Rated Wall And Floor AssembliesFire-Resistance-Rated AssembliesResolves to the current adopted revision.sync/fire-rated-wall-and-floor-assemblies, with the penetrations sealed under FirestoppingFirestoppingResolves to the current adopted revision.sync/firestopping.
6.1.4 A battery room shall not be used for storage, shall not contain equipment unrelated to the energy storage system other than the electrical equipment serving it, and shall be accessible only to authorized personnel.
6.1.5 A rooftop installation shall be located where the structural drawings show the roof framing designed for the weight of the units, shall be set clear of the fire-service access pathways and setbacks the adopted fire code requires on that roof, and shall be reachable by the fire department from the roof access.

6.2 Enclosure Form

6.2.1 The form of the battery enclosure shall be as indicated in the datasheet.
Battery Enclosure Formradio
○ Open racks or cabinets installed in a battery room
○ Factory-assembled cabinet, serviced from outside, not entered
○ Walk-in enclosure or container, entered for service
NOTE Racks or cabinets in a battery room put the room's construction, detection, suppression, and ventilation on the building and the project's fire protection trades, and they suit a building that already has the room; a factory-assembled cabinet that is never entered carries its own detection, suppression, thermal management, and explosion control under its listing, keeps every person outside the enclosure, and is the form of most building-scale systems today; a walk-in enclosure holds more energy per unit and gives a technician a conditioned space to work in, at the cost of a space a person can be inside of when a cell fails, which is why NFPA 855 treats it as a room with egress, detection, and ventilation provisions of its own. No form is the norm across the range of projects this standard covers, so the field carries no default. (6.2.2)
6.2.3 A walk-in enclosure shall have doors that swing outward and open from the inside without a key or special knowledge, an egress path of the width and travel distance the adopted building code requires for the occupancy, emergency lighting, and an exit sign, and shall not be occupied except for service.
6.2.4 A factory-assembled cabinet shall be serviced entirely from outside the enclosure through its doors, with the working space in front of every door complying with NFPA 70 110.26 for the voltage inside.

7 Battery Chemistry and Application

7.1 Battery Chemistry

7.1.1 The battery chemistry shall be as indicated in the datasheet.
Battery Chemistryradio
● Lithium iron phosphate (LFP)
○ Lithium nickel manganese cobalt oxide (NMC)
○ Lithium nickel cobalt aluminum oxide (NCA)
○ Lithium titanate (LTO)
○ Sodium-ion
○ Valve-regulated lead-acid (VRLA)
○ Vanadium redox flow
NOTE Lithium iron phosphate is the chemistry of the large majority of stationary systems sold today, because its cells enter thermal runaway at a higher temperature, release less heat when they do, and cycle for longer than the nickel-based lithium chemistries at a lower cost per kilowatt-hour, which is why it is the default; nickel manganese cobalt and nickel cobalt aluminum cells store more energy in less space and weight, which matters on a roof or in a tight room, and they bring more severe UL 9540A results and the separation and explosion control that follow; lithium titanate cells charge and discharge at very high rates, tolerate cold, and last for tens of thousands of cycles, at several times the cost per kilowatt-hour, and suit a frequency regulation or heavy-cycling duty; sodium-ion cells use no lithium, cobalt, or nickel, tolerate cold and a full discharge, and store less energy per unit volume than lithium iron phosphate, and they are the newest listed chemistry with the shortest field record; valve-regulated lead-acid stores the least energy per unit weight and volume and cycles the fewest times, at the lowest first cost and with no thermal runaway propagation behavior under UL 9540A, and it suits a backup-only duty that rarely cycles; a vanadium redox flow battery stores its energy in liquid electrolyte in tanks, separates the power rating from the energy rating so that duration can be bought by adding tank, does not degrade with cycling, and presents an electrolyte spill rather than a fire as its hazard, at a lower round-trip efficiency and a larger footprint. (7.1.2)
7.1.3 The chemistry decides the hazard, so the fire detection, suppression, explosion control, separation, and ventilation this standard requires follow from the chemistry selected and from the UL 9540A data for it, and a change of chemistry after the fire design is reviewed shall be resubmitted as a change to that design.
7.1.4 A lead-acid battery shall be ventilated to limit the hydrogen concentration in the room or enclosure to not more than 1 percent by volume in accordance with IEEE 1635 / ASHRAE 21 and NFPA 855, and shall be maintained under IEEE 1188.
7.1.5 A flow battery shall be installed with secondary containment under the electrolyte tanks, pumps, and piping sized for the volume of the largest tank plus the volume of the piping it serves, with a leak detector in the containment that alarms to the site controller, and with the electrolyte handling provisions of NFPA 855 for the electrolyte furnished.

7.2 Dispatch Applications and Design Duty

7.2.1 The applications the energy storage system is dispatched for shall be as indicated in the datasheet.
Applicationscheckbox
☐ Peak shaving and demand charge management
☐ Time-of-use energy shifting
☐ Backup of designated loads during a utility outage
☐ Photovoltaic self-consumption and clipping recovery
☐ Photovoltaic firming and ramp-rate control
☐ Frequency regulation or other utility ancillary service
☐ Demand response under a utility or aggregator program
☐ Islanded operation of a microgrid
☐ Buffering of electric vehicle charging load
☐ Voltage support and power quality at the point of interconnection
NOTE The application is a decision independent of the chemistry, and it sets the duty the battery sees: peak shaving and time-of-use shifting cycle the battery once or twice every day at a moderate rate and are the applications that pay for most building-scale systems; backup holds the battery near full charge for months and discharges it a few times a year, which is an easy duty for the cells and a hard one for the energy accounting, because the energy held in reserve is not available to shave a peak; photovoltaic self-consumption, clipping recovery, and firming cycle the battery with the sun and favor direct current coupling; frequency regulation and ancillary services cycle the battery shallowly but continuously at high rates and wear it faster than any other duty; demand response calls on it a few dozen times a year at the utility's command; islanded operation needs a grid-forming power conversion system and a controller that balances generation and load with no utility; charging load buffering follows the arrival of vehicles; voltage support uses the inverter's reactive capability with little energy throughput. Each is checked independently because a system is dispatched for several at once and the controller arbitrates among them, and no set is the norm. (7.2.2)
7.2.3 Where more than one application is selected, the site controller shall arbitrate among them by the priority the Owner directs in writing before commissioning, and the energy held in reserve for backup shall not be dispatched for any other application unless the Owner's priority permits it.
7.2.4 The design duty of the battery shall be the number of full equivalent cycles per year indicated in the datasheet, and the performance guarantee under this standard shall cover that duty.
Design Duty, Full Equivalent Cycles per Yearrange
cycles/yr
10730
NOTE A full equivalent cycle is one discharge of the usable energy, counted by throughput rather than by events, so that two half discharges are one cycle; a backup-only system sees a few dozen a year, a daily peak-shaving system sees about 365, a system shifting energy twice a day sees about 730, and a frequency regulation system can exceed that. The warranty is priced on this number, and a duty higher than the one warranted voids the capacity guarantee, so the number is stated here and not left to the manufacturer's assumption. (7.2.5)

8 Energy and Power Ratings

8.1 Usable Energy

8.1.1 The usable energy of the system, measured at the AC terminals of the power conversion system at the beginning of life, at rated discharge power, at 25 °C cell temperature, and across the state-of-charge window the manufacturer warrants, shall be as indicated in the datasheet.
Usable Energy at the AC Terminals, Beginning of Liferange
kWh
550000
Per drawings — the one-line diagram and the equipment schedules (deferred by default)
NOTE Usable energy is the figure the project is buying and the figure the capacity test measures; nameplate energy is the sum of the cell ratings, and it is larger than the usable energy by the state-of-charge window the manufacturer holds back at the top and bottom, the DC-to-AC losses, and the auxiliary load, by a margin that runs from five to fifteen percent across the market. A system specified by nameplate delivers less than the project sized for, which is why the usable figure at the AC terminals is the one stated. (8.1.2)
8.1.3 The manufacturer shall state the nameplate energy, the usable energy, the state-of-charge window, and the auxiliary power consumption at standby and at rated power in the product data, and the usable energy stated shall be not less than the usable energy indicated for the system.
8.1.4 The auxiliary power of the thermal management, the battery management system, the controller, and the heaters shall be accounted for in the usable energy and in the round-trip efficiency, and shall not be taken from the energy reserved for backup during an outage beyond the allowance the manufacturer states in the product data.

8.2 Rated Power

8.2.1 The rated continuous discharge power and the rated continuous charge power of the system, measured at the AC terminals of the power conversion system at Site Ambient Temperature MaximumSite Ambient Temperature MaximumParameterEach project supplies its own value.site-ambient-temperature-maximum, shall be as indicated in the datasheet.
Rated Continuous Power at the AC Terminalsrange
kW
520000
Per drawings — the one-line diagram and the equipment schedules (deferred by default)
NOTE The rated power is set by the application and by the capacity available at the point of interconnection, and it is stated on the one-line diagram with the overcurrent protection it requires. Where the rated charge power differs from the rated discharge power, both are stated on the equipment schedules. (8.2.2)
8.2.3 The power conversion system shall deliver the rated power continuously for the full discharge of the usable energy, and shall deliver the overload the manufacturer states in the product data for the duration stated, without tripping or derating.
8.2.4 The rated power of the power conversion system shall be stated in kilowatts and in kilovolt-amperes, and the system shall deliver its rated kilowatts at the power factor the serving utility's interconnection requirements impose at the point of interconnection.

8.3 Discharge Duration

8.3.1 The discharge duration of the system at rated power shall be as indicated in the datasheet.
Discharge Duration at Rated Powerrange
hours
0.250.51234681012
Derived — the usable energy at the AC terminals divided by the rated continuous discharge power, both as selected under this standard (by default)
NOTE The duration is not a third decision; it is the energy divided by the power, which is why the field starts derived from the two selections above it. Stating all three invites a contradiction among them, and a duration stated alone specifies nothing, because the same four hours describes a 25 kW system and a 25 MW one. Durations of two to four hours are what peak shaving and time-of-use shifting call for, a backup system is sized by the hours the designated loads must ride through, and sub-hour durations belong to power applications such as frequency regulation. (8.3.2)

8.4 Round-Trip Efficiency

8.4.1 The round-trip efficiency of the system, measured AC terminals to AC terminals over a full charge and discharge of the usable energy at rated power at 25 °C and including the auxiliary power consumed during the cycle, shall be as indicated in the datasheet.
Round-Trip Efficiency, AC to AC, at Rated Powerrange
Not less than
%
6095
NOTE The AC-to-AC figure including auxiliaries is the one that reaches the utility bill; a DC-to-DC figure at the cell terminals runs several points higher and is the one a catalog leads with. A lithium-ion system with its auxiliaries included measures in the middle to upper eighties, a lead-acid system in the upper seventies, and a vanadium flow battery with its pumps running in the upper sixties to lower seventies, so the figure follows from the chemistry selected and the thermal management load at the site, and the field carries no default. (8.4.2)
8.4.3 The round-trip efficiency measured in the capacity test under this standard shall be not less than the efficiency indicated in the datasheet, and where no value is indicated the manufacturer's stated value shall be the acceptance criterion.

8.5 Voltage at the Point of Interconnection

8.5.1 The AC voltage and phase at the point of interconnection shall be as indicated in the datasheet.
AC Voltage and Phase at the Point of Interconnectionselect
240/120 V, 1Φ
208Y/120 V, 3Φ
480Y/277 V, 3Φ
600Y/347 V, 3Φ
Medium voltage, through a step-up transformer furnished with the system
Per drawings — the one-line diagram (deferred by default)
8.5.2 The DC bus voltage class of the battery shall be as indicated in the datasheet.
DC Bus Voltage Classradio
○ 1000 V DC and below
○ Above 1000 V DC, to 1500 V DC
Manufacturer's standard (by default)
NOTE The battery voltage is a design decision of the manufacturer rather than of the project: cabinet systems are built on either bus, and the higher bus cuts the DC current and the conductor size at a given power while bringing the equipment inside the enclosure under the over-1000-volt provisions of NFPA 70 Article 490 and the electrical safety provisions that go with them. The manufacturer's standard bus is accepted, which is why the field carries the manufacturer state, and the voltage is reported in the product data. (8.5.3)
8.5.4 The manufacturer shall state the nominal, the maximum charge, and the minimum discharge voltage of the DC bus in the product data, and where the bus exceeds 1000 V DC the equipment, the working space, and the warning labels shall comply with NFPA 70 Article 490.

9 Power Conversion and Interconnection

9.1 Power Conversion System

9.1.1 The power conversion system shall be a bidirectional converter that charges the battery from the AC source and discharges it to the AC system at the rated power, with the DC side matched to the battery voltage range the manufacturer states and the AC side matched to the voltage at the point of interconnection.
9.1.2 The harmonic current the power conversion system injects at the point of interconnection shall comply with IEEE 1547 and with IEEE 519 at the point of common coupling, and the total rated-current distortion shall be stated in the product data.
9.1.3 The power conversion system shall carry its own DC and AC overcurrent protection and disconnecting means, or the one-line diagram shall show them furnished separately, and the available fault current the system contributes at the point of interconnection for the duration the inverter sustains it shall be stated in the product data for the short-circuit study under Short Circuit StudyShort-Circuit StudyResolves to the current adopted revision.sync/short-circuit-study.
NOTE An inverter contributes a fault current of only one to two times its rated current for a few cycles, which is small beside a utility or a generator, but a large system on a small bus can still move a breaker's interrupting duty, and the coordination study needs the figure and its duration rather than an assumption. (9.1.4)
9.1.5 Where the power conversion system is furnished with an isolation transformer, the transformer shall be part of the listed system, and where it is furnished without one the manufacturer shall state in the product data how the system detects a DC ground fault and limits DC injection into the AC system.

9.2 Coupling to On-Site Generation

9.2.1 The coupling of the energy storage system to on-site generation shall be as indicated in the datasheet.
Coupling to On-Site Generationradio
○ AC-coupled, with the generation on its own inverter and the storage on its own
○ DC-coupled, with the generation and the battery on a shared DC bus or a hybrid inverter
○ No on-site generation coupled to the storage
NOTE An AC-coupled system pairs a storage inverter with an existing or a separately procured generation inverter, which lets storage be added to a photovoltaic system already in service and lets each inverter be sized and listed on its own, at the cost of converting the photovoltaic energy twice before it is stored; a DC-coupled system charges the battery from the array through a DC-to-DC converter or a hybrid inverter before any AC conversion, which recovers the energy a photovoltaic inverter would clip at midday and stores it with one conversion fewer, and it suits a new array procured with the storage; a system with no generation coupled charges only from the utility. The choice follows whether generation exists and whether it is new, so the field carries no default. (9.2.2)
9.2.3 Where the system is AC-coupled to a generation inverter, the anti-islanding, the voltage and frequency settings, and the grid-support functions of both inverters shall be coordinated so that the storage inverter does not hold the generation inverter online in an island the utility has left, and the generation inverter is governed by Photovoltaic SystemsPhotovoltaic SystemsResolves to the current adopted revision.sync/photovoltaic-systems.
9.2.4 Where the system is DC-coupled, the array DC input, its overcurrent protection, and the rapid shutdown of the array conductors are governed by Photovoltaic SystemsPhotovoltaic SystemsResolves to the current adopted revision.sync/photovoltaic-systems, and the DC-to-DC converter or hybrid inverter shall be part of the UL 9540 listed system.

9.3 Grid Interaction

9.3.1 The grid interaction of the energy storage system shall be as indicated in the datasheet.
Grid Interactionradio
○ Utility-interactive, grid-following only, no operation during a utility outage
○ Utility-interactive, with islanded operation of designated loads during a utility outage
○ Stand-alone, never operated in parallel with the utility
NOTE A grid-following system runs only while the utility is present, which keeps it under IEEE 1547 alone and makes it the simplest and lowest-cost interactive system, and it is the system of a project whose applications are peak shaving and energy shifting; a system that islands designated loads forms its own voltage and frequency when the utility fails, which requires a grid-forming power conversion system, a transfer or isolation device that separates the island from the utility, a controller that balances the island, and a load study that limits the island to what the battery can carry, and it is the system of a project that is buying backup; a stand-alone system is never paralleled with the utility and falls under NFPA 70 Article 710 rather than Article 705, which suits a remote site or a utility that will not interconnect storage. Neither interactive mode is distinctly the norm across projects, so the field carries no default. (9.3.2)
9.3.3 Where islanded operation is selected, the loads served in the island shall be as indicated on the one-line diagram, and the power conversion system shall form the island voltage and frequency, shall carry the motor inrush and the step loads of those loads, and shall restart the island from a de-energized bus with no external source.
9.3.4 Where islanded operation is selected, the device that separates the island from the utility shall open before the system energizes the island and shall not reconnect until the utility has returned within the IEEE 1547 enter-service criteria for the time the serving utility requires, and the reconnection shall be a synchronized closure where the system remains energized.
9.3.5 Where islanded operation is selected and an engine-generator set also serves the island, the sharing of load between the set and the storage shall be coordinated under Generator Paralleling SwitchgearGenerator Paralleling SwitchgearResolves to the current adopted revision.sync/generator-paralleling-switchgear where paralleling switchgear is furnished and under Emergency And Standby PowerEmergency and Standby Power SystemsResolves to the current adopted revision.sync/emergency-and-standby-power for the system design, and the storage shall not be the sole alternate source for a load classified as emergency or legally required standby unless that standard assigns it.
9.3.6 Where the system is stand-alone, the system shall comply with NFPA 70 Article 710 and shall carry a plaque at the service equipment stating that a stand-alone system is present.

9.4 IEEE 1547 Performance Categories

9.4.1 The IEEE 1547 normal performance category of the power conversion system shall be as indicated in the datasheet.
IEEE 1547 Normal Performance Categoryradio
○ Category A
○ Category B
Per drawings — the utility interconnection agreement (deferred by default)
9.4.2 The IEEE 1547 abnormal performance category of the power conversion system shall be as indicated in the datasheet.
IEEE 1547 Abnormal Performance Categoryradio
○ Category I
○ Category II
○ Category III
Per drawings — the utility interconnection agreement (deferred by default)
NOTE The serving utility assigns both categories in the interconnection agreement, and the inverter is set to them, which is why both fields are deferred to that document rather than chosen here. Normal Category A requires the minimum reactive power capability and suits a system on a stiff distribution circuit; Category B requires more reactive capability and the volt-var and volt-watt functions, and most utilities now assign it to storage. Abnormal Category I rides through the least disturbance and is assigned where the utility treats the system as a small addition; Category II rides through the disturbances a bulk-system event imposes; Category III rides through the most and is assigned where the circuit carries a high penetration of distributed resources and the utility wants them to stay connected through a fault elsewhere. (9.4.3)
9.4.4 The power conversion system shall be listed to UL 1741 Supplement SB for the normal and abnormal performance categories assigned, and 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.
9.4.5 The voltage and frequency trip settings, the ride-through settings, the enter-service settings, and the grid-support function settings shall be set to the values in the interconnection agreement, shall be recorded in the settings record, and shall be protected from change by a password or a utility-controlled access level.
9.4.6 The anti-islanding protection shall detect the loss of the utility and cease to energize the utility side within the time IEEE 1547 requires, and the method shall be stated in the product data.

9.5 Export Control

9.5.1 The export of power from the energy storage system to the utility shall be as indicated in the datasheet.
Export to the Utilityradio
○ Export permitted up to the limit in the interconnection agreement
○ Limited export enforced by a listed power control system
○ No export, enforced by a listed power control system or a reverse-power relay
Per drawings — the utility interconnection agreement (deferred by default)
NOTE Whether the system may 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 participates in the utility's programs and sells energy, and it needs the full interconnection study; a limited-export system is held to a setpoint below the circuit's hosting capacity, which often shortens the utility's review; a non-export system never pushes power past the service point and is interconnected under the simplest review, and it is the arrangement of a peak-shaving system on a circuit the utility will not accept generation on. The power control system that enforces the limit is listed to UL 3141 and recognized by NFPA 70 705.13. (9.5.2)
9.5.3 Where limited or no export is selected, the power control system shall be listed to UL 3141, 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 system output to zero on loss of the measurement.
9.5.4 Where no export is enforced by a reverse-power relay rather than a power control system, the relay shall trip the system within the time the serving utility requires and shall be a utility-grade relay the utility accepts.

9.6 Point of Interconnection

9.6.1 The point at which the energy storage system connects to the premises wiring shall be as indicated in the datasheet.
Point of Interconnectionradio
○ 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 energy storage system
○ Downstream of a transfer switch, on the standby bus
Per drawings — the one-line diagram (deferred by default)
NOTE A load-side connection lands on an existing switchboard or panelboard and is limited by the 120 percent bus rule and the sum-of-breakers rule of NFPA 70 705.12, which a large system on a small board cannot meet; a supply-side connection taps the service conductors ahead of the service disconnect and avoids the bus limits at the cost of a service-rated disconnect and the utility's coordination; a dedicated service gives the system its own meter and is the arrangement of a utility program that meters storage separately; a connection on the standby bus behind a transfer switch places the system where it can serve the loads a generator serves, and it is the arrangement of a system bought for backup. The point is a one-line decision, which is why it is deferred to that drawing. (9.6.2)
9.6.3 The equipment at the point of interconnection, the disconnecting means, and the overcurrent protection shall comply with NFPA 70 Article 705 for the point selected, and the equipment and the bus ratings there are governed by the standard for that equipment named in Scope.
9.6.4 A disconnecting means for the energy storage system shall be provided in accordance with NFPA 70 706.15, readily accessible, within sight of the system or lockable in the open position, and marked with the nominal voltage, the available fault current, the arc-flash label required under Arc Flash StudyArc-Flash StudyResolves to the current adopted revision.sync/arc-flash-study, and the date the fault current was calculated.
9.6.5 A permanent plaque or directory shall be installed at the service equipment and at every point of interconnection in accordance with NFPA 70 705.10, identifying every power source on the premises and the location of the energy storage system disconnecting means, with the plaque furnished under Electrical IdentificationWiring System IdentificationResolves to the current adopted revision.sync/electrical-identification.
9.6.6 The surge protection of the power conversion system AC terminals shall be as the manufacturer's listing requires, and a surge protective device furnished at the point of interconnection shall comply with Surge Protective DevicesSurge Protective DevicesResolves to the current adopted revision.sync/surge-protective-devices.

9.7 Metering

9.7.1 The metering furnished with the energy storage system shall be as indicated in the datasheet.
Metering Furnished with the Systemcheckbox
☐ Revenue-grade bidirectional meter at the AC terminals of the power conversion system
☐ Utility-approved net generation output meter
☐ Submeter on the auxiliary power supply of the system
NOTE A revenue-grade meter at the AC terminals is what verifies the capacity guarantee and the efficiency against the figures bought, and most performance guarantees are settled on it; a net generation output meter is the utility's meter where a program pays for storage discharge separately from the building; a submeter on the auxiliary supply separates the energy the thermal management and the controller consume from the energy the battery stores, which is the only way the measured round-trip efficiency can be apportioned between the cells and the site conditions. The meters are furnished under the power monitoring standard; this field decides which ones exist. (9.7.2)
9.7.3 The meters selected shall comply with Electrical Power MonitoringElectrical Power Monitoring and MeteringResolves to the current adopted revision.sync/electrical-power-monitoring, shall be read by the site controller, and shall be the basis of the capacity and efficiency measurements in the field tests under this standard.

10 Battery Management, Site Controller, and Communications

10.1 Battery Management System

10.1.1 The battery management system shall be part of the UL 9540 listed system and shall follow IEEE 2686, and it shall monitor every cell or cell group voltage, the temperature of every module at the locations the listing requires, every string current, and the insulation resistance of the DC bus to ground.
10.1.2 The battery management system shall calculate and report the state of charge, the state of health, and the remaining usable energy of each string and of the system, and shall balance the cells of each string to hold them within the voltage spread the manufacturer states.
10.1.3 The battery management system shall protect each string against overvoltage, undervoltage, overcurrent, overtemperature, undertemperature, and loss of insulation resistance by opening the string contactor, and shall report every protective operation with its cause to the site controller.
10.1.4 The battery management system shall isolate a string on a protective trip without taking the remaining strings out of service, and the system shall continue to operate at the reduced power and energy the remaining strings support.
10.1.5 The battery management system shall detect the conditions that precede thermal runaway in the cells it monitors, including a cell voltage falling while the string charges and a module temperature rising faster than the manufacturer's threshold, and shall open the string contactor and signal the fire alarm interface and the site controller on detection.
10.1.6 The battery management system shall hold its protective settings in non-volatile memory, shall restrict changes to them to the manufacturer's authorized access level, and shall log every change with the time and the user.
NOTE The management system is the layer that stops a cell fault from becoming a module fire, and it has to see a fault that develops over minutes in a single cell among thousands: the voltage droop of a cell with an internal short is small, and the temperature rise ahead of runaway is local to one module, so the resolution of the monitoring and the threshold of the response decide whether the fire detection in the enclosure ever has anything to detect. (10.1.7)

10.2 Site Controller

10.2.1 The site controller shall dispatch the power conversion system for the applications selected under this standard, shall read the battery management system, the power conversion system, the thermal management, the fire and gas detection, and the meters, and shall hold the system within the warranted duty.
10.2.2 The site controller shall log, at an interval of one minute or shorter, the state of charge, the charge and discharge power, the AC voltage and frequency, the cell temperature range, the alarms and events, and the dispatch command in effect, and shall retain the log for not less than one year on the controller and export it in a non-proprietary format.
10.2.3 The site controller shall limit the charge and discharge power so that the full equivalent cycles per year do not exceed the design duty selected under this standard, and shall report the cumulative throughput against the warranted throughput.
10.2.4 On loss of communication with the Owner's systems or the manufacturer's monitoring service, the site controller shall continue to operate the system under the last dispatch schedule in effect and under every protective function, and shall not take the system offline for a communication loss alone.

10.3 Communications to the Owner's Systems

10.3.1 The interfaces by which the site controller communicates with the Owner's systems shall be as indicated in the datasheet.
Communications to the Owner's Systemscheckbox
☑ Modbus TCP
☐ DNP3
☐ BACnet/IP to the building automation system
☐ OPC UA
☑ Hardwired dry contacts for the summary alarm, the fire alarm interface, and the emergency shutdown
NOTE Modbus TCP is the protocol nearly every storage controller speaks and the one the meters and the inverter already use, which is why it is in the default set; DNP3 is the protocol of utility SCADA and is furnished where the utility or an aggregator dispatches the system; BACnet/IP lets the building automation system read the storage without a gateway and is furnished where the building operator watches it from the same screen as the chillers; OPC UA is the interface of an industrial plant historian; the hardwired contacts are the signals that have to work when every network is down, which is why they are in the default set regardless of the protocol furnished. (10.3.2)
10.3.3 The interface protocol the power conversion system presents to the serving utility shall be as indicated in the datasheet.
IEEE 1547 Interoperability Interfacecheckbox
☐ SunSpec Modbus
☐ IEEE 2030.5
☐ DNP3
NOTE IEEE 1547 requires an interactive resource to present at least one of the three interfaces, and the utility names the one it will use in its interconnection requirements; SunSpec Modbus is the interface most inverters carry natively, IEEE 2030.5 is the interface the utilities that monitor and curtail distributed resources through a certified gateway require, and DNP3 is the interface of the utilities that treat the system as a SCADA point. Which the utility names is a project fact, so the field carries no default and records what the agreement requires. (10.3.4)
10.3.5 Where the building automation system reads the storage data, the points furnished shall be coordinated with Building Automation SystemBuilding Automation SystemResolves to the current adopted revision.sync/building-automation-system, and the network cabling to the site controller shall be installed under Structured CablingStructured Cabling SystemsResolves to the current adopted revision.sync/structured-cabling.

10.4 Remote Monitoring and Manufacturer Access

10.4.1 The remote monitoring of the energy storage system and the manufacturer's access to it shall be as indicated in the datasheet.
Remote Monitoring and Manufacturer Accessradio
● Manufacturer-hosted monitoring with remote access through an Owner-controlled secure gateway, with Owner access to the portal
○ Owner-hosted monitoring only, with no outbound connection from the system
NOTE Manufacturer-hosted monitoring is the condition of the performance guarantee on nearly every system, because the manufacturer will not warrant a battery it cannot see, and it is the arrangement on most projects, which is why it is the default; Owner-hosted monitoring with no outbound connection is the arrangement of a facility whose security policy forbids an outside connection to a device on the power system, and it requires the manufacturer to accept the Owner's log export in place of live data or to send a technician to read the system. (10.4.2)
10.4.3 Where the manufacturer has remote access, the access shall pass through a gateway the Owner controls, shall be authenticated per user with multi-factor authentication, shall be logged with the time, the user, and the action, and shall be revocable by the Owner without taking the system offline.
10.4.4 The battery management system, the site controller, and the power conversion system shall support authenticated and encrypted communications, shall ship with no default credentials in service, and shall accept firmware updates only when signed by the manufacturer and installed with the Owner's approval.

11 Thermal Management

11.1 Thermal Management Method

11.1.1 The thermal management method of the battery shall be as indicated in the datasheet.
Thermal Management Methodradio
○ Forced-air cooling and heating by an air conditioner integral to the enclosure
○ Liquid cooling and heating of the modules by a chiller integral to the enclosure
○ Conditioning of the battery room by the building mechanical system, with air circulation within the racks
NOTE Forced air through the modules from an integral air conditioner is the simplest system to service and the method of most cabinet systems at moderate power, and it holds a wider spread of temperature between the cells nearest the supply and those farthest from it; liquid cooling through cold plates under the modules holds the cells within a degree or two of one another, rejects more heat per unit of enclosure volume, and is the method of high-power and high-density systems, at the cost of a coolant loop and a chiller inside the enclosure; conditioning by the building mechanical system is the method of a battery room, and it places the cell temperature in the hands of the mechanical design and the controls of the building rather than the manufacturer. No method is the norm across the enclosure forms this standard covers, so the field carries no default. (11.1.2)
11.1.3 The thermal management shall hold every cell within the temperature range the manufacturer warrants for charging and for discharging at the rated power and the design duty, at Site Ambient Temperature MaximumSite Ambient Temperature MaximumParameterEach project supplies its own value.site-ambient-temperature-maximum and Site Ambient Temperature MinimumSite Ambient Temperature MinimumParameterEach project supplies its own value.site-ambient-temperature-minimum, and the manufacturer shall state the heat rejected at rated power in the product data.
11.1.4 The temperature spread between the warmest and the coolest cell in a string at rated power shall not exceed the spread the manufacturer's warranty is conditioned on, and that spread shall be stated in the product data.
11.1.5 The thermal management equipment shall be fed from the system's auxiliary supply, shall operate during a utility outage from the battery where the system is dispatched for backup or islanding, and its consumption during the outage shall be included in the energy accounting under this standard.
11.1.6 A refrigeration system integral to the enclosure shall comply with ASHRAE 15 for the refrigerant and the charge, and the refrigerant and the charge shall be stated in the product data.
11.1.7 A liquid cooling system shall be filled with the coolant the manufacturer specifies, shall carry a leak detector that alarms to the site controller, and shall be arranged so that a coolant leak drains away from the modules and the DC bus.
11.1.8 Where the battery room is conditioned by the building mechanical system, the mechanical drawings shall show the cooling capacity for the heat rejected at rated power, the heating at Site Ambient Temperature MinimumSite Ambient Temperature MinimumParameterEach project supplies its own value.site-ambient-temperature-minimum, and the exhaust ventilation this standard requires, and the loss of room conditioning shall alarm to the site controller and reduce the system power to what the room can hold.
NOTE A battery that runs warm ages fast, a battery that runs cold cannot charge, and a string whose cells sit at different temperatures falls out of balance; the capacity guarantee is written against a temperature range, and the thermal management is the equipment that keeps the guarantee alive, which is why its capacity is calculated at the site's design temperatures rather than at the catalog's. (11.1.9)

12 Enclosure Construction

12.1 Enclosure Material and Finish

12.1.1 The material of the outdoor enclosure or cabinet shall be as indicated in the datasheet.
Outdoor Enclosure Materialradio
● Galvanized steel with a factory-applied powder or polyester coating
○ Aluminum with a factory-applied coating
○ Stainless steel
NOTE Coated galvanized steel is the enclosure of nearly every outdoor storage cabinet and container and is the material the manufacturers list, which is why it is the default; aluminum is lighter, which matters on a roof, and does not rust at a scratch, at a higher cost and a lower resistance to impact; stainless steel is selected for a marine or chemical site where a coating would not last the warranty term. (12.1.2)
12.1.3 The enclosure shall be fabricated with a continuous roof that sheds water away from the doors, with door gaskets that maintain the enclosure type, with lockable doors keyed to the Owner's keying system or fitted with a padlock provision, and with a floor or base that is sealed against water entry at the raceway entries.
12.1.4 The enclosure shall carry the deflagration vents, the pressure-relief openings, the ventilation openings, and the suppression discharge provisions in the locations and sizes the UL 9540 listing and the explosion control design require, and no opening shall be field-cut in an enclosure.
12.1.5 An enclosure or a battery room shall carry lighting inside and at the doors of the level the manufacturer's instructions require for service, with the lighting of a walk-in enclosure fed from the auxiliary supply and including emergency lighting.
12.1.6 An enclosure containing a liquid cooling system or a lead-acid or flow battery shall have a sealed floor or a drip pan that contains the largest single spill the enclosure can produce.

12.2 Enclosure Thermal Insulation and Condensation Control

12.2.1 An outdoor enclosure shall be insulated and shall include the heating and the humidity control that hold the interior above the dew point at Site Ambient Temperature MinimumSite Ambient Temperature MinimumParameterEach project supplies its own value.site-ambient-temperature-minimum and within the humidity range the manufacturer warrants.
NOTE A cabinet that is cooled below the dew point of the air that enters it sweats on its bus and its boards, and a cabinet that is left unheated in a cold climate condenses when a thaw follows a freeze; the insulation and the humidity control are the enclosure's defense against the ground fault that follows. (12.2.2)

13 Fire, Gas, and Explosion Safety

13.1 Unit Energy and Aggregate Energy

13.1.1 The energy of each unit and the aggregate energy in each fire area, room, enclosure, or outdoor group shall not exceed the limits NFPA 855 and the adopted fire code set for the chemistry and the installation location, except as larger units or larger aggregates are permitted under those documents on the basis of the UL 9540A installation-level test results and the hazard mitigation analysis accepted by the Authority Having Jurisdiction.
NOTE NFPA 855 limits the energy in one unit and the energy in one room or group for each chemistry, and it permits both limits to be exceeded where the UL 9540A data show that a failure in a full-size unit does not propagate to its neighbor, which is how a cabinet several times the prescriptive unit limit comes to be installed; the limit and the path past it are both in the code, and the shop drawings show which one the installation relies on. (13.1.2)
13.1.3 The energy of each unit and of each group as installed shall be shown on the arrangement shop drawings with the limit it is installed under, and a unit or group installed under the UL 9540A alternative shall be identified as such on the record drawings.

13.2 Separation Distances

13.2.1 The separation between units and between each unit and every exposure shall be as indicated in the datasheet.
Separation Between Units and to Exposuresrange
Not less than
ft
050
Derived — the UL 9540A installation-level test results accepted by the Authority Having Jurisdiction, and the separation NFPA 855 prescribes for the chemistry and installation location where those results do not justify less (by default)
NOTE NFPA 855 prescribes 3 ft between units and from walls indoors and 10 ft from lot lines, public ways, buildings, stored combustibles, and hazardous materials outdoors, and it permits each to be reduced where UL 9540A installation-level testing shows that a failure in one unit does not ignite its neighbor at the closer spacing; a cabinet tested side by side with no gap is listed to be installed that way, which is why the field admits zero and starts derived from the test data rather than carrying a value. The value as derived is shown on the arrangement shop drawings and governs the layout. (13.2.2)
13.2.3 The separation to the lot line, to a public way, to a building, to a means of egress, and to stored combustibles shall be shown on the arrangement shop drawings, and a unit shall not be installed closer to any of them than the separation derived under this standard.
13.2.4 Where the UL 9540A installation-level results are the basis for a separation less than NFPA 855 prescribes, the separation shall not be less than the spacing at which the installation-level test was conducted, and the exposure wall or barrier in the test, where one was used, shall be reproduced in the installation.
13.2.5 An outdoor unit shall be accessible to the fire department along an approach the adopted fire code accepts, with a water supply for manual firefighting within the distance that code requires, as indicated on the site plan.

13.3 Fire Detection

13.3.1 The fire detection furnished within each unit, enclosure, or battery room shall be as indicated in the datasheet.
Fire Detection within the Unit or Roomcheckbox
☑ Smoke detection, spot type
☐ Smoke detection, aspirating type
☐ Heat detection
☐ Off-gas detection at the module level, ahead of smoke
☑ Flammable gas detection at the lower flammability limit
☑ Battery management system thermal runaway detection
NOTE Spot smoke detection is what NFPA 855 requires in a room or a walk-in enclosure and what the listing of most cabinets includes, which is why it is in the default set, and aspirating detection samples the air continuously and detects the first particles of a venting cell minutes earlier at a higher cost; heat detection is slow for a cell fault and is furnished where the environment defeats smoke detection; off-gas detection senses the electrolyte vapor a cell releases before it smokes and is the earliest warning available, and it is furnished where the response it triggers, a shutdown and ventilation, can stop the event; flammable gas detection at the lower flammability limit is the sensor that starts the explosion prevention ventilation and is required wherever NFPA 69 ventilation is the explosion control, which is why it is in the default set; the battery management system's own detection is the layer that acts before any of the others and is in the default set because every listed system carries it. (13.3.2)
13.3.3 The fire detection shall be listed for the purpose, shall be powered and supervised as NFPA 72 requires, and shall initiate the alarm, shutdown, ventilation, and suppression responses the sequence of operation under this standard assigns to each detector.
13.3.4 An aspirating smoke detection system shall be a listed system with its sampling pipe arranged to draw from each module bay or rack as the manufacturer's listing requires, and its alert and alarm thresholds shall be recorded in the settings record.
13.3.5 A factory-assembled cabinet shall carry the detection its UL 9540 listing includes, and detection added in the field shall not alter the configuration under which the cabinet was listed.

13.4 Gas Detection and Ventilation

13.4.1 Where the chemistry releases flammable gas in a failure, flammable gas detection shall be furnished in every room, walk-in enclosure, and cabinet that is not listed as not requiring it, and the detection shall alarm at the concentration indicated in the datasheet.
Flammable Gas Alarm Thresholdrange
Not more than
% LFL
1025
Default: 25 % LFL
NOTE NFPA 855 and NFPA 69 set 25 percent of the lower flammability limit as the concentration at which the explosion prevention ventilation starts and the system shuts down, and it is the threshold nearly every installation is set to, which is why it is the default; a lower threshold starts the ventilation earlier at the cost of nuisance operation from a sensor that drifts, and it is set where the enclosure is small enough that the concentration rises faster than the ventilation can follow. A measured concentration at or below the threshold selected is the condition the constraint reads. (13.4.2)
13.4.3 On a flammable gas alarm, the system shall open every string contactor and stop charging and discharging, shall start the explosion prevention ventilation where furnished, shall signal the fire alarm interface, and shall not restart until the gas has cleared and the system has been inspected by the manufacturer's technician.
13.4.4 The gas detectors shall be of a type suited to the gas the UL 9540A cell test identifies, shall be located where the gas accumulates for its density, shall be calibrated at the interval the manufacturer states and at commissioning, and shall report a sensor fault as a supervisory signal.
13.4.5 A battery room or a walk-in enclosure shall be provided with mechanical exhaust ventilation at not less than 1 cfm per square foot of floor area, operating continuously or started by the gas detection, exhausting to the outdoors away from openings and air intakes, with the fan furnished under HVAC FansHVAC FansResolves to the current adopted revision.sync/hvac-fans in spark-resistant construction and with its failure alarmed as a supervisory signal.
13.4.6 Exhaust ventilation of a battery room or walk-in enclosure shall operate on the auxiliary supply through a utility outage, and the system shall reduce its power to zero when the ventilation is lost.

13.5 Fire Suppression

13.5.1 The fire suppression furnished for the energy storage system shall be as indicated in the datasheet.
Fire Suppressionradio
○ Automatic sprinklers in the room or building, designed under NFPA 13
○ Clean agent total flooding of the enclosure, integral to the listed unit
○ Condensed aerosol within the enclosure, integral to the listed unit
○ Water mist within the enclosure, integral to the listed unit
○ No suppression beyond the listed unit's construction, where the UL 9540A installation-level results and the hazard mitigation analysis support it
NOTE Sprinklers are what NFPA 855 requires in a battery room and in most dedicated-use buildings, and water is the only agent that cools a cell in thermal runaway, so it is the suppression of every indoor installation and of an outdoor walk-in enclosure the Authority Having Jurisdiction treats as a room; a clean agent flooding the enclosure knocks down the flame of a venting module and leaves no residue, and it is the suppression integral to many walk-in containers, but it does not cool the cells and the fire can relight when the agent clears; condensed aerosol does the same in a cabinet too small to pipe and is the suppression integral to most factory-assembled cabinets; water mist cools as well as suppresses and fits inside an enclosure where sprinklers cannot be fed; no suppression beyond the enclosure is the arrangement NFPA 855 permits for an outdoor unit whose installation-level test shows that a failure stays inside the unit and whose hazard mitigation analysis the Authority Having Jurisdiction accepts. The suppression follows the enclosure form and the location, so the field carries no default. (13.5.2)
13.5.3 Where sprinklers are selected, the sprinkler system shall be designed to a density of 0.3 gpm per square foot over a 2,500 square foot design area, or to the density and area the UL 9540A installation-level results support and the Authority Having Jurisdiction approves, and the system is furnished under Wet Pipe Fire Sprinkler SystemsWet-Pipe Fire Sprinkler SystemsResolves to the current adopted revision.sync/wet-pipe-fire-sprinkler-systems with that design basis stated to it.
13.5.4 Where a clean agent, condensed aerosol, or water mist system integral to the unit is selected, the system shall be the one the UL 9540 listing of the unit includes, shall be listed to NFPA 2001, UL 2775, or NFPA 750 as applicable, shall discharge on the detection the listing assigns, and shall report its discharge and its trouble to the fire alarm interface.
13.5.5 Where no suppression beyond the listed unit is selected, the hazard mitigation analysis shall show that the UL 9540A installation-level results support it for the separation and the exposures as installed, and the Authority Having Jurisdiction's acceptance shall be obtained in writing before the unit is procured.
13.5.6 A clean agent or aerosol system in a walk-in enclosure shall be interlocked to the door so that the discharge is inhibited while a person is inside, and shall carry the manual release, the abort, and the signage its listing requires.
13.5.7 A room-flooding clean agent system installed as a building system to protect a battery room, rather than integral to the listed unit, is governed by Clean Agent Fire SuppressionClean Agent Fire Suppression SystemsResolves to the current adopted revision.sync/clean-agent-fire-suppression, with the agent and the hold time coordinated with the UL 9540A data under this standard.

13.6 Explosion Control

13.6.1 The explosion control of each room, walk-in enclosure, and cabinet shall be as indicated in the datasheet.
Explosion Controlradio
○ Deflagration venting designed to NFPA 68
○ Explosion prevention by gas detection and ventilation designed to NFPA 69
○ Deflagration venting and explosion prevention ventilation together
○ None, where the UL 9540A test data show that no flammable gas accumulates in the enclosure
NOTE A cell that vents releases a flammable gas mixture, and NFPA 855 requires every lithium-ion installation to control the deflagration that mixture can produce unless the UL 9540A data show that it does not accumulate. Deflagration venting fits panels in the enclosure that open at a set pressure and direct the deflagration outdoors, which is the control of most factory-assembled cabinets, where the volume is small and a vent panel is simple; explosion prevention by ventilation dilutes the gas below its lower flammability limit before it can ignite, by a fan started by the gas detection, and it is the control of a battery room and a walk-in enclosure, where there are people and no roof to vent through; the two together are specified where the room is large enough to need the ventilation and the Authority Having Jurisdiction wants the venting as well; none is the arrangement the code permits for a chemistry and enclosure whose test data show the gas does not reach a flammable concentration. The control follows the enclosure form and the test data, so the field carries no default. (13.6.2)
13.6.3 Deflagration vents shall be designed under NFPA 68 for the gas volume and composition the UL 9540A test identifies, shall discharge where the vented gas and flame do not reach a person, an opening, an exposure, or another unit, and shall be the vents the UL 9540 listing of the unit includes where the unit is factory-assembled.
13.6.4 Explosion prevention ventilation shall be designed under NFPA 69 to hold the concentration below 25 percent of the lower flammability limit at the gas release rate the UL 9540A test identifies, shall be started by the gas detection, and shall be the exhaust ventilation this standard requires for the room or enclosure or a separate system of that capacity.
13.6.5 The explosion control shall remain operable through a utility outage and after the fire suppression has discharged.

13.7 Emergency Shutdown

13.7.1 An emergency shutdown control shall be provided at each unit or enclosure and at a remote location indicated on the electrical plans, and its operation shall open every string contactor, stop the power conversion system, and open the AC disconnecting means of the system.
13.7.2 The emergency shutdown shall be initiated by the fire alarm interface on a fire alarm or gas alarm, by the battery management system on a thermal runaway detection, and manually at the controls, and it shall not be reset remotely.
13.7.3 The emergency shutdown control shall be a mushroom-head push-button with a protective collar, labeled as the emergency shutdown for the energy storage system, and located where a responder can reach it without entering the enclosure or the room.
NOTE A shutdown removes the voltage the system produces but not the energy the cells hold, and a responder has to know that the battery behind an open contactor is still charged; the responder information under this standard says so, and the shutdown is placed where it can be reached while the enclosure is burning. (13.7.4)

13.8 Fire Alarm Interface

13.8.1 The interface between the energy storage system and the fire alarm shall be as indicated in the datasheet.
Fire Alarm Interfaceradio
○ Alarm, supervisory, and trouble signals to the building fire alarm control unit
○ Dedicated listed fire alarm control unit at the system, transmitting to a supervising station
○ Signals to the Owner's monitoring system only, where the Authority Having Jurisdiction requires no fire alarm monitoring
NOTE Where the building has a fire alarm system, the storage system's smoke, heat, gas, and suppression signals go to it and the building system transmits them to the supervising station, which is the arrangement of every indoor installation and of most outdoor units at a building; a dedicated control unit at the system is the arrangement of a remote outdoor site with no building system to connect to, and it carries its own transmitter; signals to the Owner's monitoring alone is the arrangement NFPA 855 permits only where the Authority Having Jurisdiction does not require monitoring, as for some small systems. The arrangement follows the site, so the field carries no default. (13.8.2)
13.8.3 The energy storage system shall furnish, at a terminal cabinet at the unit, a separate supervised contact for fire alarm, for gas alarm, for suppression discharge, for supervisory conditions including detector fault and ventilation failure, and for trouble, and the monitoring of those contacts and the transmission of the signals are governed by Fire Alarm SystemsFire Alarm SystemsResolves to the current adopted revision.sync/fire-alarm-systems.
13.8.4 The fire alarm interface shall initiate the emergency shutdown under this standard and shall report the shutdown as a supervisory signal.

13.9 Hazard Mitigation Analysis

13.9.1 Whether a hazard mitigation analysis is required for the installation shall be as indicated in the datasheet.
Hazard Mitigation Analysisradio
○ Required
○ Not required
Derived — the chemistry, the installation location, the unit and aggregate energy against the NFPA 855 limits, the reliance on UL 9540A results in place of a prescriptive requirement, and the requirement of the Authority Having Jurisdiction (by default)
NOTE NFPA 855 requires a hazard mitigation analysis where the installation exceeds a prescriptive limit, departs from a prescriptive requirement on the strength of UL 9540A data, uses a chemistry the code does not list, or where the Authority Having Jurisdiction asks for one, and the analysis is accepted by that authority before the permit; whether one is required follows from those facts, which is why the field starts derived from them. (13.9.2)
13.9.3 Where a hazard mitigation analysis is required, it shall be prepared by a fire protection engineer licensed in the state of the project, shall evaluate thermal runaway in a single cell, a single module, and a single unit, the failure of each protective system, the loss of the thermal management, a fire from an exposure, and the stranded energy after an event, and shall state the mitigation relied on for each.
13.9.4 The hazard mitigation analysis shall be submitted to the Authority Having Jurisdiction with the permit application and shall be accepted in writing before the system is procured.

13.10 Emergency Response Plan and Responder Information

13.10.1 An emergency response plan shall be prepared in accordance with NFPA 855, covering the hazards of the chemistry, the location of the shutdown controls and disconnecting means, the stranded energy after an event, the actions to take on each alarm, the procedure for a fire including the water supply and the duration of cooling the manufacturer recommends, the handling of damaged modules, and the contacts at the Owner and the manufacturer.
13.10.2 The responder information required by NFPA 855 and the adopted fire code shall be posted at the entrance to the room or enclosure and in a weatherproof holder at the outdoor unit, including the chemistry, the energy stored, the NFPA 704 placard, the location of the shutdown controls, and a 24-hour contact number.
13.10.3 The Contractor shall arrange one orientation of the responding fire department at the site before the system is energized, attended by the manufacturer's technician, covering the plan, the shutdown controls, and the hazards, and shall record the attendance in the closeout submittals.
13.10.4 The signage required by NFPA 70 Article 706, NFPA 855, and the adopted fire code at the system, the disconnecting means, the room door, and the enclosure doors shall be furnished under Electrical IdentificationWiring System IdentificationResolves to the current adopted revision.sync/electrical-identification with the content this standard requires.

14 Testing and Commissioning

14.1 Factory Tests

14.1.1 The energy storage system shall be tested at the factory before shipment, and the factory test shall include a full charge and discharge of each unit at rated power with the energy measured, a functional test of every battery management system protective function by simulation, a functional test of the power conversion system protective and grid-support functions, a functional test of the fire and gas detection and the suppression release circuits, and a test of the communications interfaces.
14.1.2 The witnessing of the factory test shall be as indicated in the datasheet.
Factory Test Witnessingradio
● Certified factory test report, not witnessed
○ Witnessed at the factory by the Owner's and the Engineer's representatives
○ Witnessed remotely by live video and data feed
NOTE A certified report is what most projects accept, which is why it is the default; a witnessed test at the factory is bought where the system is large enough that a shortfall found at the site would delay the project by the shipping time, and the travel is a small cost beside it; a remote witness sees the data and the discharge curve at a fraction of the cost of the trip. (14.1.3)
14.1.4 The factory test report shall record the measured usable energy of each unit at rated power, the round-trip efficiency, the cell temperature range during the discharge, and the result of every functional test, and the system shall not ship until the measured energy of each unit meets the usable energy the unit is sold to deliver.

14.2 Field Acceptance Tests

14.2.1 Field acceptance tests shall be performed after the installation is complete and before the system is operated in parallel with the utility, in accordance with ANSI/NETA ATS and Electrical Acceptance TestingElectrical Acceptance TestingResolves to the current adopted revision.sync/electrical-acceptance-testing for the method, the instruments, the criteria, and the report, and shall include the tests indicated in the datasheet.
Field Acceptance Testscheckbox
☑ Visual and mechanical inspection including anchorage, separation distances, clearances, nameplates, and the integrity of the enclosure
☑ Bolted connection resistance or torque verification
☑ Insulation resistance of the DC bus and the AC feeder
☑ Grounding and bonding continuity and the DC ground-fault detection
☑ Battery management system protective functions by simulation, each string
☑ Power conversion system trip, ride-through, enter-service, and grid-support settings verified against the settings record
☑ Anti-islanding test by loss of the utility source
☐ Export limit or non-export test at the power control system
☑ Fire detection, gas detection, suppression release, and ventilation functional tests by simulation at each device
☑ Emergency shutdown from each control, with the contactors and the disconnecting means confirmed open
☑ Fire alarm interface signals confirmed at the receiving control unit
☑ Communications points confirmed at the Owner's systems and the monitoring portal
☑ Capacity test at rated power
☑ Round-trip efficiency measured at the meter
☐ Island formation, load carrying, and resynchronization test, where islanded operation is selected
☑ Thermal management performance with cell temperatures logged through the capacity test
☐ Infrared scan of the DC and AC terminations under load
14.2.3 The capacity test shall charge the system to the top of its warranted state-of-charge window, rest it as the manufacturer directs, discharge it at rated power to the bottom of that window with the energy measured at the AC terminals by the revenue-grade meter or a calibrated analyzer, and record the energy, the duration, the cell temperature range, and the auxiliary energy consumed.
14.2.4 The usable energy measured in the capacity test, corrected to 25 °C by the manufacturer's published temperature correction where the cell temperature during the test was outside 20 °C to 30 °C, shall be not less than the percentage of the usable energy indicated in the datasheet.
Capacity Test Acceptance, Measured Energy as a Percentage of the Specified Usable Energyrange
Not less than
%
95100
NOTE The usable energy is specified at the beginning of life, and the capacity test is the beginning of life, so the measured energy is expected to reach the figure bought; an acceptance below 100 percent recognizes that a revenue-grade meter, a temperature correction, and a state-of-charge estimate each carry an uncertainty of a percent or two, and a project that sets the threshold at 100 percent settles those uncertainties against the Contractor. Where the threshold is set depends on how the project treats measurement uncertainty, so the field carries no default. (14.2.5)
14.2.6 A system that measures below the acceptance threshold shall not be accepted, the manufacturer shall add capacity or replace modules at no cost to the Owner until a repeated capacity test meets the threshold, and the cost of every repeated test shall be borne by the Contractor.
14.2.7 Where islanded operation is selected, the island test shall open the utility source with the designated loads connected, shall confirm that the system forms the island and carries the loads including the largest motor start, shall run the island for not less than one hour, and shall confirm the synchronized reconnection when the utility source is restored.
14.2.8 The interconnection commissioning tests the serving utility requires under IEEE 1547.1 shall be performed in the utility's presence where it so requires, and the system shall not be operated in parallel with the utility until the utility's permission to operate is in hand.
14.2.9 The commissioning required by NFPA 855 shall follow the commissioning plan submitted under this standard, shall include the functional tests of every fire, gas, ventilation, suppression, and shutdown system in the integrated sequence from detection through response, and shall be documented in a commissioning report delivered with the closeout submittals; where a commissioning authority is engaged under CommissioningTotal Building CommissioningResolves to the current adopted revision.sync/commissioning, that authority shall witness the integrated test.
14.2.10 A system that fails any field acceptance 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.

14.3 Site Acceptance Witnessing

14.3.1 The witnessing of the field acceptance tests and the capacity test shall be as indicated in the datasheet.
Site Acceptance Witnessingradio
○ Witnessed by the Engineer of Record or the Owner's representative
○ Witnessed by an independent third party engaged by the Owner
○ Certified by the testing firm and the manufacturer, not witnessed
NOTE The Engineer or the Owner's representative witnessing the tests is the arrangement of most building projects and costs the project nothing beyond the day; an independent third party is required by some incentive programs and by lenders on a financed system, and it is selected where the capacity guarantee is the basis of a payment; a certified test is the arrangement of a small system where the witnessing would cost more than the system. No arrangement is the norm across the sizes this standard covers, so the field carries no default. (14.3.2)

14.4 Training

14.4.1 The Contractor shall conduct training for the Owner's operating staff before substantial completion, of the duration indicated in the datasheet, conducted by the manufacturer's technician, covering the operation of the site controller and the portal, the reading and the meaning of the alarms, the response to each alarm under the emergency response plan, the reset of the system after a shutdown, the maintenance schedule the warranty requires, and the records the warranty requires the Owner to keep.
Owner Training Durationrange
Not less than
hours
224
NOTE A half day covers a cabinet system whose operation is a portal and whose maintenance is a filter change; a day or more covers a walk-in system with a liquid cooling loop, an island mode, and a dispatch schedule the Owner will edit. The duration follows the system, so the field carries no default. (14.4.2)

15 Installation

15.1 Placement and Clearances

15.1.1 Each unit shall be set in the location and with the separation the record of the arrangement shop drawings shows, and no unit shall be moved from that location without the Engineer of Record's acceptance of a revised arrangement.
15.1.2 Working space in front of every door, every disconnecting means, and the power conversion system shall comply with NFPA 70 110.26 for the voltage inside, and the clearance above and around the enclosure for the thermal management airflow and the deflagration vent discharge shall be as the manufacturer's instructions require.
15.1.3 An outdoor unit shall be set on a cast-in-place pad constructed under Concrete PadsConcrete Equipment PadsResolves to the current adopted revision.sync/concrete-pads or on the precast or steel base the manufacturer lists with the unit, with the top of the pad not less than 4 in. above the finished grade, sloped to drain away from the unit, and with the raceway entries through the pad sealed against water and gas.
15.1.4 An outdoor unit located where a vehicle can strike it shall be protected by bollards furnished under Site Furnishings And BollardsSite Furnishings and BollardsResolves to the current adopted revision.sync/site-furnishings-and-bollards or by a curb or barrier, as indicated on the site plan, set so that they do not reduce the working space or the fire department access.
15.1.5 An outdoor installation shall be enclosed by security fencing furnished under Fencing And GatesFencing and GatesResolves to the current adopted revision.sync/fencing-and-gates where the drawings so indicate, with the fence set outside the separation distance and the working space and with a gate the fire department can open.
15.1.6 A unit installed where Site Ambient Temperature MinimumSite Ambient Temperature MinimumParameterEach project supplies its own value.site-ambient-temperature-minimum is below freezing shall be set with its doors and its deflagration vents clear of the snow depth and the drifting the site produces, and where snow accumulates against the enclosure a roof or a snow fence shall protect the vents.

15.2 Electrical Connections

15.2.1 The DC conductors between the battery and the power conversion system shall be the conductors the UL 9540 listing includes where they are furnished with the system, and where they are field-installed they shall be sized, insulated for the DC voltage, and installed under Conductors And CablesConductors and CablesResolves to the current adopted revision.sync/conductors-and-cables in raceways under Raceways And ConduitRaceways and ConduitResolves to the current adopted revision.sync/raceways-and-conduit dedicated to the DC circuit.
15.2.2 The AC feeder from the power conversion system to the point of interconnection and the control and communication wiring shall be installed under Conductors And CablesConductors and CablesResolves to the current adopted revision.sync/conductors-and-cables, Raceways And ConduitRaceways and ConduitResolves to the current adopted revision.sync/raceways-and-conduit, and Structured CablingStructured Cabling SystemsResolves to the current adopted revision.sync/structured-cabling, and the raceways shall enter the enclosure only at the entries the manufacturer provides.
15.2.3 Every conductor termination in the system 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 field acceptance test report.
15.2.4 The grounding and bonding of the system, including the equipment grounding of every enclosure and rack, the bonding of the pad reinforcement where the manufacturer requires it, and the grounding of the DC system in the configuration the listing requires, shall comply with Grounding And BondingGrounding and Bonding for Electrical SystemsResolves to the current adopted revision.sync/grounding-and-bonding.
15.2.5 The raceway entries into a room or enclosure that contains the battery shall be sealed against the passage of gas into other spaces, and the penetrations of a rated room shall be sealed under FirestoppingFirestoppingResolves to the current adopted revision.sync/firestopping.
15.2.6 No unit shall be energized until the field acceptance tests this standard names for energization have been passed, the fire and gas detection and the shutdown chain have been tested, and the Authority Having Jurisdiction has inspected the installation.

15.3 Identification

15.3.1 Each unit shall carry the manufacturer's listing mark, the nameplate and usable energy, the rated power, the DC and AC voltages, the chemistry, and the date of manufacture as applied by the manufacturer.
15.3.2 Each disconnecting means, each emergency shutdown control, the point of interconnection, and the room or enclosure door shall be labeled as NFPA 70 Articles 705 and 706 and NFPA 855 require, with the labels furnished under Electrical IdentificationWiring System IdentificationResolves to the current adopted revision.sync/electrical-identification.
15.3.3 The arc-flash warning label on each enclosure door and disconnecting means shall state the incident energy and the arc-flash boundary determined under Arc Flash StudyArc-Flash StudyResolves to the current adopted revision.sync/arc-flash-study for the DC and the AC sides, and shall state that the battery remains energized after the disconnecting means is opened.

16 Delivery, Storage, and Handling

16.1 Lithium-ion modules shall be shipped under 49 CFR 173.185 with the UN 38.3 test summary available, at the state of charge the manufacturer specifies for transport, and the shipping state of charge shall be recorded on the delivery documents.
16.2 Each unit and each module shall be inspected at receipt for physical damage, for the integrity of the listing marks, and for conformance with the reviewed submittal, and the state of charge of each module shall be read and recorded at receipt.
16.3 Modules and units shall be stored within the manufacturer's published storage temperature and humidity range, off the ground, protected from water, and for not longer than the maximum storage time the manufacturer states before a maintenance charge is required, and a maintenance charge shall be performed and recorded where that time is exceeded.
16.4 A module that is dented, swollen, leaking, wet, or that reads a voltage below the manufacturer's minimum shall be quarantined outdoors at the separation NFPA 855 requires from buildings and other modules, shall not be installed, and shall be removed from the site by the manufacturer within five working days.
NOTE A lithium-ion cell stored below its minimum voltage grows copper inside and becomes a cell that can short when it is charged, and a cell left at full charge for months loses life it never recovers; the state of charge in transport and storage is a safety record and a warranty record at once, which is why it is read and written down at every hand-off. (16.5)
16.6 Units shall be lifted only at the lifting points the manufacturer provides, with the rigging the manufacturer's instructions specify, and a unit shall not be rolled, dragged, or tilted beyond the angle the instructions permit.

17 Decommissioning

17.1 The responsibility for the decommissioning and recycling of the system at end of life shall be as indicated in the datasheet.
Decommissioning and Recycling Responsibilityradio
○ Manufacturer take-back included in the purchase, with removal and recycling at the manufacturer's cost at end of life
○ Owner's responsibility at end of life, with the manufacturer's decommissioning plan and a recycler named
NOTE A take-back included in the purchase prices the removal and the recycling into the system and hands the Owner nothing to arrange twenty years on, at a higher first cost and a reliance on the manufacturer still existing; leaving it to the Owner costs less now and leaves the Owner to contract the removal with a plan in hand. Neither is the norm, so the field carries no default. (17.1.1)
17.1.2 A decommissioning plan shall be prepared in accordance with NFPA 855, stating how the system is discharged to the state of charge safe for transport, how the strings are isolated and the modules removed, how the modules are packaged and shipped under 49 CFR 173.185, the recycler or the take-back program that receives them, and how the electrolyte of a flow battery or the acid of a lead-acid battery is drained and disposed of.
17.1.3 Modules removed after a fire, a thermal event, or physical damage shall be handled as damaged, defective, or recalled cells under 49 CFR 173.185 and shall not be shipped as ordinary lithium batteries.

18 Warranty

18.1 Performance Warranty

18.1.1 The manufacturer shall warrant the usable energy of the system for the term indicated in the datasheet, measured from the date of substantial completion, at the design duty selected under this standard and at the cell temperatures the thermal management under this standard holds.
Performance Warranty Termrange
Not less than
years
225
Default: 10 years
NOTE A ten-year performance warranty is the term the market sells building-scale lithium-ion storage with and the term most projects specify, which is why it is the default; a shorter term is what a lead-acid system or a system in a heavy duty is offered, and a longer term is bought as an extension where the project finances the system over its life. (18.1.2)
18.1.3 The usable energy at the end of the warranty term shall be not less than the percentage of the specified usable energy indicated in the datasheet.
Usable Energy Retained at the End of the Warranty Termrange
Not less than
% of specified usable energy
50100
NOTE A lithium iron phosphate system in a daily duty retains seventy to eighty percent of its energy after ten years, a nickel-based system somewhat less, and a flow battery nearly all of it; the figure follows from the chemistry and the duty and is the figure the guarantee is written against, so the field carries no default. A retention of 100 percent records that the guarantee is met by augmentation rather than by the cells. (18.1.4)
18.1.5 The basis on which the manufacturer meets the capacity guarantee shall be as indicated in the datasheet.
Capacity Guarantee Basisradio
○ Degradation guarantee: the installed cells retain the specified energy at the end of the term
○ Augmentation guarantee: the manufacturer adds modules during the term to hold the usable energy at the specified value
NOTE A degradation guarantee lets the energy fall along a warranted curve and pays out if it falls faster, which suits a project that sized the system for the end-of-term energy; an augmentation guarantee holds the energy at the specified value by adding cells as the installed ones age, which keeps a peak-shaving system doing in year nine what it did in year one, at the cost of space and electrical capacity reserved for the added modules and a service visit the Owner has to allow. Neither is the norm, so the field carries no default. (18.1.6)
18.1.7 Where an augmentation guarantee is selected, the enclosure, the DC bus, and the point of interconnection shall be furnished with the space and the capacity for the modules the manufacturer projects adding over the term, and the projected augmentation schedule shall be stated in the warranty documentation.
18.1.8 The performance warranty shall state the duty, the temperature range, the maintenance, and the monitoring it is conditioned on, and no condition shall require a duty lighter, a temperature range narrower, or a maintenance more frequent than this standard and the reviewed submittals establish.

18.2 Defects and Availability

18.2.1 The manufacturer shall warrant the battery, the battery management system, the power conversion system, the site controller, the thermal management equipment, and the enclosure against defects in materials and workmanship for the performance warranty term, with the coverage indicated in the datasheet.
Warranty Coverageradio
○ Parts
○ Parts and on-site labor
NOTE A parts warranty ships the module or the board and leaves the Owner to pay a technician to install it, which suits an Owner with a maintenance contract; a parts and labor warranty brings the manufacturer's technician to the site and is bought where the Owner has no one trained on the system or where a day of downtime costs the Owner a demand charge. Neither is the norm, so the field carries no default. (18.2.2)
18.2.3 The annual availability the manufacturer guarantees for the system shall be as indicated in the datasheet.
Guaranteed Annual Availabilityrange
Not less than
%
909597989999.5
NOTE An availability guarantee is the warranty of a system whose value is earned every day, as a peak-shaving system's is: a single missed peak in a month costs the demand charge for the month, and a system that is down for a firmware fault in that hour has failed although nothing in it is defective. Ninety-five to ninety-eight percent is what the market guarantees on a monitored system; where no value is selected, the manufacturer guarantees none and the Owner's remedy is the defects warranty alone. (18.2.4)
18.2.5 Where an availability guarantee is selected, the availability shall be measured by the site controller log as the fraction of the year the system is able to charge and discharge at rated power, excluding scheduled maintenance the Owner has approved and utility outages where the system is not dispatched for backup, and the remedy for a shortfall shall be as the Contract states.
18.2.6 The Contractor shall warrant the installation, including every termination, the anchorage, the raceway entries, the pad, and the results of the field acceptance tests, for the project warranty period, and shall correct a defect in it at no cost to the Owner.
18.2.7 A module or component 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 state of health to the string it joins as the manufacturer's instructions require.

19 Spare Parts

19.1 The spare part types to be delivered with the system shall be as indicated in the datasheet.
Spare Part Typescheckbox
☐ Battery modules
☐ Battery management system boards and string contactors
☐ DC and AC fuses of each rating installed
☐ Power conversion system power modules and fans
☐ Thermal management filters, fans, and coolant
☐ Gas detector sensor elements
☐ Suppression agent cylinders or aerosol units
☐ Door gaskets and enclosure hardware
19.2 The number of spare battery modules shall be as indicated in the datasheet, as a percentage of the installed module count, rounded up to a whole module.
Spare Battery Modulesrange
% of installed modules
12510
NOTE Spare modules age on the shelf as the installed ones age in service, and a module held for years cannot join a string without a state-of-health match, so a spare module quantity is a trade between the time a string is down waiting for the manufacturer and the modules that may never be used; the fuses, the sensor elements, and the filters are the spares that are used, and they cost little. No quantity is the norm, so the field carries no default, and a zero records that the Owner relies on the manufacturer's stock. (19.3)
19.4 Spare modules shall be stored at the state of charge and the temperature the manufacturer specifies, shall be given the maintenance charge the manufacturer requires at the stated interval, and the Contractor shall deliver them with a written storage instruction and obtain a signed receipt.
19.5 Spare parts shall be identical to and interchangeable with the installed parts, shall be the parts the manufacturer lists for the system, and shall be delivered in their original packaging and labeled with the unit and the part they serve.

Written and maintained by SynC. Licensed under CC BY 4.0.