Article 620

Solar Photovoltaic (PV) Systems

Part I. General

Scope. This article applies to solar PV systems, other than those covered by Article 691, including the array circuit(s), inverter(s), and controller(s) for such systems. [See Figure 690.1(a) and Figure 690.1(b).] The systems covered by this article may be interactive with other electrical power produc‐ tion sources or stand-alone or both, and may or may not be connected to energy storage systems such as batteries. These PV systems may have ac or dc output for utilization.
Informational Note: Article 691 covers the installation of large-scale PV electric supply stations.
Definitions.Alternating-Current (ac) Module (Alternating-Current Photo‐ voltaic Module). A complete, environmentally protected unit consisting of solar cells, optics, inverter, and other components, exclusive of tracker, designed to generate ac power when exposed to sunlight.Array. A mechanically integrated assembly of module(s) or panel(s) with a support structure and foundation, tracker, and other components, as required, to form a dc or ac power- producing unit.Bipolar Photovoltaic Array. A dc PV array that has two outputs, each having opposite polarity to a common reference point or center tap.•DC-to-DC Converter. A device installed in the PV sourcecircuit or PV output circuit that can provide an output dc volt‐ age and current at a higher or lower value than the input dc voltage and current.NDC-to-DC Converter Output Circuit. Circuit conductors between the dc-to-dc converter source circuit(s) and the inver‐ ter or dc utilization equipment.NDC-to-DC Converter Source Circuit. Circuits between dc-to-dc converters and from dc-to-dc converters to the common connection point(s) of the dc system.Direct-Current (dc) Combiner. A device used in the PV source and PV output circuits to combine two or more dc circuit inputs and provide one dc circuit output.Diversion Charge Controller. Equipment that regulates the charging process of a battery by diverting power from energy storage to direct-current or alternating-current loads or to an interconnected utility service.Electrical Production and Distribution Network. A power production, distribution, and utilization system, such as a utility system and connected loads, that is external to and not control‐ led by the PV power system.Functional Grounded PV System. A PV system that has an elec‐ trical reference to ground that is not solidly grounded.

Interactive inverter PV system disconnect             Electricproduction and Inverter output circuit distributionPV power source networkInteractive system

PV power PV system Interactive system source disconnect Multimode disconnect       inverter Electric productionand distribution networkStand-aloneDC loads systemInverter loadsEnergy storage outputsystem disconnect circuitsEnergy storage systemDC coupled multimode system

PV power Interactivesource inverter Inverter output circuit                        PV system disconnectEnergy storage Multimode system inverterElectricproduction and distributionEnergy storage networksystem disconnect Interactive systemAC coupled multimode systemdisconnect
PV power PV system Stand-alonesource disconnect inverter Inverter                               outputcircuitPV system Stand-aloneDC circuit(s) DC loads system loads Energy storagesystem disconnect
Energy storage systemStand-alone system
Notes:
1. These diagrams are intended to be a means of identification for PV system components, circuits, and connections.
2. The PV system disconnect in these diagrams separates the PV system from all other systems.
3. Not all disconnecting means required by Article 690, Part III are shown.
4. System grounding and equipment grounding are not shown. See Article 690, Part V.
5. Custom designs occur in each configuration, and some components are optional.

FIGURE 690.1(b) Identification of PV System Components in Common Configurations.

Informational Note: A functional grounded PV system is often connected to ground through a fuse, circuit breaker, resistance device, non-isolated grounded ac circuit, or electronic means that is part of a listed ground-fault protection system. Conduc‐ tors in these systems that are normally at ground potential may have voltage to ground during fault conditions.

Inverter output circuit

Electric production

and distribution network

PV system disconnect

AC module (includes inverter)

Array (of AC modules)

AC module system

Generating Capacity. The sum of parallel-connected inverter maximum continuous output power at 40°C in kilowatts.

Interactive System. A PV system that operates in parallel with and may deliver power to an electrical production and distribu‐ tion network.

Interactive Inverter Output Circuit. The conductors between the interactive inverter and the service equipment or another electrical power production and distribution network.

Inverter. Equipment that is used to change voltage level or waveform, or both, of electrical energy. Commonly, an inverter [also known as a power conditioning unit (PCU) or power conversion system (PCS)] is a device that changes dc input to an ac output. Inverters may also function as battery chargers that use alternating current from another source and convert it into direct current for charging batteries.

Inverter Input Circuit. Conductors connected to the dc input of an inverter.

Inverter Output Circuit. Conductors connected to the ac output of an inverter.

Module. A complete, environmentally protected unit consist‐ ing of solar cells, optics, and other components, exclusive of tracker, designed to generate dc power when exposed to sunlight.

Monopole Subarray. A PV subarray that has two conductors in the output circuit, one positive (+) and one negative (−). Two monopole PV subarrays are used to form a bipolar PV array.

Multimode Inverter. Equipment having the capabilities of both the interactive inverter and the stand-alone inverter.

Panel. A collection of modules mechanically fastened together, wired, and designed to provide a field-installable unit.

Photovoltaic Output Circuit. Circuit conductors between the PV source circuit(s) and the inverter or dc utilization equip‐ ment.

Photovoltaic Power Source. An array or aggregate of arrays that generates dc power at system voltage and current.

Photovoltaic Source Circuit. Circuits between modules and from modules to the common connection point(s) of the dc system.

Photovoltaic System DC Circuit. Any dc conductor supplied by a PV power source, including PV source circuits, PV output circuits, dc-to-dc converter source circuits, or dc-to-dc converter output circuits.

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Solar Cell. The basic PV device that generates electricity when

exposed to light.

Stand-Alone System. A solar PV system that supplies power independently of an electrical production and distribution network.

Subarray. An electrical subset of a PV array.

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690.4 General Requirements.

Photovoltaic Systems. Photovoltaic systems shall be permitted to supply a building or other structure in addition to any other electrical supply system(s).
Equipment. Inverters, motor generators, PV modules, PV panels, ac modules, dc combiners, dc-to-dc converters, and charge controllers intended for use in PV systems shall be listed or field labeled for the PV application.
Qualified Personnel. The installation of equipment and all associated wiring and interconnections shall be performed only by qualified persons.Informational Note: See Article 100 for the definition of quali‐ fied person.
Multiple PV Systems. Multiple PV systems shall be permit‐ ted to be installed in or on a single building or structure. Where the PV systems are remotely located from each other, a directory in accordance with 705.10 shall be provided at each PV system disconnecting means.N•
Locations Not Permitted. PV system equipment and

disconnecting means shall not be installed in bathrooms.

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Alternating-Current (ac) Modules.
1. Photovoltaic Source Circuits. The requirements of Article 690 pertaining to PV source circuits shall not apply to ac modules. The PV source circuit, conductors, and inverters shall be considered as internal wiring of an ac module.
2. Inverter Output Circuit. The output of an ac module shall be considered an inverter output circuit.
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Part II. Circuit Requirements
Maximum Voltage. The maximum voltage of PV system dc circuits shall be the highest voltage between any two circuit conductors or any conductor and ground. PV system dc circuits on or in one- and two-family dwellings shall be permitted to have a maximum voltage of 600 volts or less. PV system dc circuits on or in other types of buildings shall be permitted to have a maximum voltage of 1000 volts or less. Where not loca‐ ted on or in buildings, listed dc PV equipment, rated at a maxi‐ mum voltage of 1500 volts or less, shall not be required to comply with Parts II and III of Article 490.Informational Note: One source for lowest-expected, ambienttemperature design data for various locations is the chapter titled Extreme Annual Mean Minimum Design Dry Bulb Temperature found in the ASHRAE Handbook — Fundamentals, 2013. These temperature data can be used to calculate maxi‐ mum voltage.
1. Photovoltaic Source and Output Circuits. In a dc PV source circuit or output circuit, the maximum PV system volt‐ age for that circuit shall be calculated in accordance with one of the following methods:
  1. Instructions in listing or labeling of the module: The sum of the PV module–rated open-circuit voltage of the series- connected modules corrected for the lowest expected ambient temperature using the open-circuit voltage temperature coefficients in accordance with the instruc‐ tions included in the listing or labeling of the module
  2. Crystalline and multicrystalline modules: For crystalline and multicrystalline silicon modules, the sum of the
  •PV module–rated open-circuit voltage of the series- connected modules corrected for the lowest expected ambient temperature using the correction factor provi‐ ded in Table 690.7(A)(3) PV systems of 100 kW or larger: For PV systems with agenerating capacity of 100 kW or greater, a documented and stamped PV system design, using an industry stand‐ ard method and provided by a licensed professional elec‐ trical engineer, shall be permitted.Informational Note: One industry standard method for calculat‐ ing maximum voltage of a PV system is published by Sandia National Laboratories, reference SAND 2004-3535, Photovoltaic Array Performance Model.
  The maximum voltage shall be used to determine the volt‐age rating of conductors, cables, disconnects, overcurrent devices, and other equipment.
2. DC-to-DC Converter Source and Output Circuits. In a dc- to-dc converter source and output circuit, the maximum volt‐ age shall be calculated in accordance with 690.7(B)(1) or (B)(2).(2) Two or More Series Connected DC-to-DC Converters. For circuits connected to the output of two or more series- connected dc-to-dc converters, the maximum voltage shall be determined in accordance with the instructions included in the listing or labeling of the dc-to-dc converter. If these instructions do not state the rated voltage of series-connected dc-to-dc converters, the maximum voltage shall be the sum of the maxi‐ mum rated voltage output of the dc-to-dc converters in series.
  1. Single DC-to-DC Converter. For circuits connected to the output of a single dc-to-dc converter, the maximum voltage shall be the maximum rated voltage output of the dc-to-dc converter.
- (C) Bipolar Source and Output Circuits. For 2-wire dc circuits connected to bipolar PV arrays, the maximum voltage shall be the highest voltage between the 2-wire circuit conductors where one conductor of the 2-wire circuit is connected to the functional ground reference (center tap). To prevent overvolt‐ age in the event of a ground-fault or arc-fault, the array shall be
  Table 690.7(A) Voltage Correction Factors for Crystalline and Multicrystalline Silicon Modules Correction Factors for Ambient Temperatures Below 25°C (77°F). (Multiply the rated open-circuit voltage by the appropriate correction factor shown below.)Ambient Temperature (°C)
  FactorAmbient Temperature (°F)24 to 201.0276 to 6819 to 151.0467 to 5914 to 101.0658 to 509 to 51.0849 to 414 to 01.1040 to 32–1 to –51.1231 to 23–6 to –101.1422 to 14–11 to –151.1613 to 5–16 to –201.184 to –4–21 to –251.20–5 to –13–26 to –301.21–14 to –22–31 to –351.23–23 to –31–36 to –401.25–32 to –40
  isolated from the ground reference and isolated into two 2-wire circuits.•
Circuit Sizing and Current.
1. Calculation of Maximum Circuit Current. The maximum current for the specific circuit shall be calculated in accordance with 690.8(A)(1) through (A)(6).Informational Note: Where the requirements of 690.8(A)(1) and (B)(1) are both applied, the resulting multiplication factor is 156 percent.
  1. Photovoltaic Source Circuit Currents. The maximum current shall be calculated by one of the following methods:
    1. The sum of parallel-connected PV module–rated short- circuit currents multiplied by 125 percentInformational Note: One industry standard method for calculat‐ing maximum current of a PV system is available from Sandia National Laboratories, reference SAND 2004-3535, Photovoltaic Array Performance Model. This model is used by the System Advi‐ sor Model simulation program provided by the National Renew‐ able Energy Laboratory.
    2. For PV systems with a generating capacity of 100 kW or greater, a documented and stamped PV system design, using an industry standard method and provided by a licensed professional electrical engineer, shall be permit‐ ted. The calculated maximum current value shall be based on the highest 3-hour current average resulting from the simulated local irradiance on the PV array accounting for elevation and orientation. The current value used by this method shall not be less than 70 percent of the value calculated using 690.8(A)(1)(1).
    1. Photovoltaic Output Circuit Currents. The maximum current shall be the sum of parallel source circuit maximum currents as calculated in 690.8(A)(1).
    2. Inverter Output Circuit Current. The maximum current shall be the inverter continuous output current rating.
    3. Stand-Alone Inverter Input Circuit Current. The maxi‐ mum current shall be the stand-alone continuous inverter input current rating when the inverter is producing rated power at the lowest input voltage.
    4. DC-to-DC Converter Source Circuit Current. The maxi‐ mum current shall be the dc-to-dc converter continuous output current rating.N
    5. DC-to-DC Converter Output Circuit Current. The maxi‐ mum current shall be the sum of parallel connected dc-to-dc converter source circuit currents as calculated in 690.8(A)(5).
2. Conductor Ampacity. PV system currents shall be consid‐ ered to be continuous. Circuit conductors shall be sized to carry not less than the larger of 690.8(B)(1) or (B)(2) or where protected by a listed adjustable electronic overcurrent protec‐ tive device in accordance 690.9(B)(3), not less than the current in 690.8(B)(3).
  1. Before Application of Adjustment and Correction Factors. One hundred twenty-five percent of the maximum currents calculated in 690.8(A) before the application of adjustment and correction factors.Exception: Circuits containing an assembly, together with its overcur‐ rent device(s), that is listed for continuous operation at 100 percent of its rating shall be permitted to be used at 100 percent of its rating.
  2. After Application of Adjustment and Correction Factors. The maximum currents calculated in 690.8(A) after the appli‐ cation of adjustment and correction factors.N
  3. Adjustable Electronic Overcurrent Protective Device. The rating or setting of an adjustable electronic overcurrent protec‐ tive device installed in accordance with 240.6.
3. Systems with Multiple Direct-Current Voltages. For a PV power source that has multiple output circuit voltages and employs a common-return conductor, the ampacity of the common-return conductor shall not be less than the sum of the ampere ratings of the overcurrent devices of the individual output circuits.
4. Sizing of Module Interconnection Conductors. Where a single overcurrent device is used to protect a set of two or more parallel-connected module circuits, the ampacity of each of the module interconnection conductors shall not be less than the sum of the rating of the single overcurrent device plus 125 percent of the short-circuit current from the other parallel- connected modules.
Overcurrent Protection.
1. Circuits and Equipment. PV system dc circuit and inverter output conductors and equipment shall be protected against overcurrent. Overcurrent protective devices shall not be required for circuits with sufficient ampacity for the highest available current. Circuits connected to current limited supplies (e.g., PV modules, dc-to-dc converters, interactive inverter output circuits) and also connected to sources having higher current availability (e.g., parallel strings of modules, utility power) shall be protected at the higher current source connection.Exception: An overcurrent device shall not be required for PV modules or PV source circuit or dc-to-dc converters source circuit conductors sized in accordance with 690.8(B) where one of the following applies:
  1. There are no external sources such as parallel-connected source circuits, batteries, or backfeed from inverters.
  2. The short-circuit currents from all sources do not exceed the ampacity of the conductors and the maximum overcurrent protec‐ tive device size rating specified for the PV module or dc-to-dc converter.
  Informational Note: Photovoltaic system dc circuits are current limited circuits that only need overcurrent protection when connected in parallel to higher current sources. The overcur‐ rent device is often installed at the higher current source end of the circuit.
2. Overcurrent Device Ratings. Overcurrent devices used in PV system dc circuits shall be listed for use in PV systems. Over‐ current devices, where required, shall be rated in accordance with one of the following:
  1. Not less than 125 percent of the maximum currents calculated in 690.8(A).
  2. An assembly, together with its overcurrent device(s), that is listed for continuous operation at 100 percent of its rating shall be permitted to be used at 100 percent of its rating.
  (3) Adjustable electronic overcurrent protective devices ratedor set in accordance with 240.6.
  Informational Note: Some electronic overcurrent protectivedevices prevent backfeed current.•
  Informational Note: Due to improved ground-fault protectionrequired in PV systems by 690.41(B), a single overcurrent protective device in either the positive or negative conductors of a PV system in combination with this ground-fault protection provides adequate overcurrent protection.
3. Photovoltaic Source and Output Circuits. A single over‐ current protective device, where required, shall be permitted to protect the PV modules and conductors of each source circuit or the conductors of each output circuit. Where single overcur‐ rent protection devices are used to protect PV source or output circuits, all overcurrent devices shall be placed in the same polarity for all circuits within a PV system. The overcurrent devices shall be accessible but shall not be required to be read‐ ily accessible.
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4. Power Transformers. Overcurrent protection for a trans‐
former with a source(s) on each side shall be provided in accordance with 450.3 by considering first one side of the trans‐ former, then the other side of the transformer, as the primary.Exception: A power transformer with a current rating on the side connected toward the interactive inverter output, not less than the rated continuous output current of the inverter, shall be permitted without overcurrent protection from the inverter.
Stand-Alone Systems. The wiring system connected to a stand-alone system shall be installed in accordance with 710.15.•
Arc-Fault Circuit Protection (Direct Current). Photo‐interrupter orovoltaic systems operating at 80 volts dc or greater between any two conductors shall be protected by a listed PV arc-fault circuit ther system components listed to provide equiv‐alent protection. The system shall detect and interrupt arcing faults resulting from a failure in the intended continuity of a conductor, connection, module, or other system component in the PV system dc circuits.Informational Note: Annex A includes the reference for thePhotovoltaic DC Arc-Fault Circuit Protection product standard.•
Exception: For PV systems not installed on or in buildings, PV outputcircuits and dc-to-dc converter output circuits that are direct buried, installed in metallic raceways, or installed in enclosed metallic cable trays are permitted without arc-fault circuit protection. Detached struc‐ tures whose sole purpose is to house PV system equipment shall not be considered buildings according to this exception.
Rapid Shutdown of PV Systems on Buildings. PV system circuits installed on or in buildings shall include a rapid shutdown function to reduce shock hazard for emergency responders in accordance with 690.12(A) through (D).Exception: Ground mounted PV system circuits that enter buildings, ofwhich the sole purpose is to house PV system equipment, shall not be required to comply with 690.12.•
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1. Controlled Conductors. Requirements for controlled conductors shall apply to PV circuits supplied by the PV system.N
2. Controlled Limits. The use of the term array boundary in this section is defined as 305 mm (1 ft) from the array in all directions. Controlled conductors outside the array boundary shall comply with 690.12(B)(1) and inside the array boundary shall comply with 690.12(B)(2).
  1. Outside the Array Boundary. Controlled conductors loca‐ ted outside the boundary or more than 1 m (3 ft) from the point of entry inside a building shall be limited to not morethan 30 volts within 30 seconds of rapid shutdown initiation. Voltage shall be measured between any two conductors and between any conductor and ground.
  2. Inside the Array Boundary. The PV system shall comply with one of the following:
    1. The PV array shall be listed or field labeled as a rapid shutdown PV array. Such a PV array shall be installed and used in accordance with the instructions included with the rapid shutdown PV array listing or field labeling.Informational Note: A listed or field labeled rapid shutdown PV array is evaluated as an assembly or system as defined in the installation instructions to reduce but not eliminate risk of elec‐ tric shock hazard within a damaged PV array during fire-fighting procedures. These rapid shutdown PV arrays are designed to reduce shock hazards by methods such as limiting access to energized components, reducing the voltage difference between energized components, limiting the electric current that might flow in an electrical circuit involving personnel with increased resistance of the conductive circuit, or by a combination of such methods.
    2. Controlled conductors located inside the boundary or not more than 1 m (3 ft) from the point of penetration of the surface of the building shall be limited to not more than 80 volts within 30 seconds of rapid shutdown initia‐ tion. Voltage shall be measured between any two conduc‐ tors and between any conductor and ground.
    3. PV arrays with no exposed wiring methods, no exposed conductive parts, and installed more than 2.5 m (8 ft) from exposed grounded conductive parts or ground shall not be required to comply with 690.12(B)(2).
    The requirement of 690.12(B)(2) shall become effective January 1, 2019.N
3. Initiation Device. The initiation device(s) shall initiate the rapid shutdown function of the PV system. The device “off” position shall indicate that the rapid shutdown function has been initiated for all PV systems connected to that device. For one-family and two-family dwellings, an initiation device(s) shall be located at a readily accessible location outside the building.The rapid shutdown initiation device(s) shall consist of at least one of the following:
  1. Service disconnecting means
  2. PV system disconnecting means
  3. Readily accessible switch that plainly indicates whether it is in the “off” or “on” position
  Informational Note: One example of why an initiation device that complies with 690.12(C)(3) would be used is where a PV system is connected to an optional standby system that remains energized upon loss of utility voltage.Where multiple PV systems are installed with rapid shutdown functions on a single service, the initiation device(s) shall consist of not more than six switches or six sets of circuit break‐ ers, or a combination of not more than six switches and sets of circuit breakers, mounted in a single enclosure, or in a group of separate enclosures. These initiation device(s) shall initiate the rapid shutdown of all PV systems with rapid shutdown func‐ tions on that service. Where auxiliary initiation devices are installed, these auxiliary devices shall control all PV systems with rapid shutdown functions on that service.
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4. Equipment. Equipment that performs the rapid shut‐ down functions, other than initiation devices such as listed disconnect switches, circuit breakers, or control switches, shall be listed for providing rapid shutdown protection.
Informational Note: Inverter input circuit conductors often remain energized for up to 5 minutes with inverters not listed for rapid shutdown.
Part III. Disconnecting Means
Photovoltaic System Disconnecting Means. Means shall be provided to disconnect the PV system from all wiring systems including power systems, energy storage systems, and utilization equipment and its associated premises wiring.

Location. The PV system disconnecting means shall be installed at a readily accessible location.Informational Note: PV systems installed in accordance with690.12 address the concerns related to energized conductors entering a building.•
Marking. Each PV system disconnecting means shall plainly indicate whether in the open (off) or closed (on) posi‐ tion and be permanently marked “PV SYSTEM DISCONNECT” or equivalent. Additional markings shall be permitted based upon the specific system configuration. For PV system discon‐ necting means where the line and load terminals may be ener‐ gized in the open position, the device shall be marked with the following words or equivalent:WARNING ELECTRIC SHOCK HAZARDTERMINALS ON THE LINE AND LOADSIDES MAY BE ENERGIZED IN THE OPEN POSITIONThe warning sign(s) or label(s) shall comply with 110.21(B).
Suitable for Use. If the PV system is connected to the supply side of the service disconnecting means as permitted in 230.82(6), the PV system disconnecting means shall be listed as suitable for use as service equipment.Informational Note: This requirement does not limit thenumber of PV systems connected to a service as permitted in 690.4(D). This requirement allows up to six disconnecting means to disconnect a single PV system. For PV systems where all power is converted through interactive inverters, a dedicated circuit breaker, in 705.12(B)(1), is an example of a single PV system disconnecting means.
Maximum Number of Disconnects. Each PV system disconnecting means shall consist of not more than six switches or six sets of circuit breakers, or a combination of not more than six switches and sets of circuit breakers, mounted in a single enclosure, or in a group of separate enclosures. A single PV system disconnecting means shall be permitted for the combined ac output of one or more inverters or ac modules in an interactive system.
Ratings. The PV system disconnecting means shall have ratings sufficient for the maximum circuit current available short-circuit current, and voltage that is available at the termi‐ nals of the PV system disconnect.
Type of Disconnect.N
1. Simultaneous Disconnection. The PV system disconnect‐ ing means shall simultaneously disconnect the PV system conductors of the circuit from all conductors of other wiring systems. The PV system disconnecting means shall be an exter‐ nally operable general-use switch or circuit breaker, or other approved means. A dc PV system disconnecting means shall be marked for use in PV systems or be suitable for backfeed opera‐ tion.
2. Devices Marked “Line” and “Load.” Devices marked with “line” and “load” shall not be permitted for backfeed or reverse current.
3. DC-Rated Enclosed Switches, Open-Type Switches, and Low-Voltage Power Circuit Breakers. DC-rated, enclosed switches, open-type switches, and low-voltage power circuit breakers shall be permitted for backfeed operation.

Informational Note: The purpose of these isolating devices are

for the safe and convenient replacement or service of specific PV system equipment without exposure to energized conduc‐ tors.

690.15 Disconnection of Photovoltaic Equipment. Isolating devices shall be provided to isolate PV modules, ac PV modules, fuses, dc-to-dc converters inverters, and charge controllers from all conductors that are not solidly grounded. An equip‐ ment disconnecting means or a PV system disconnecting means shall be permitted in place of an isolating device. Where the maximum circuit current is greater than 30 amperes for the output circuit of a dc combiner or the input circuit of a charge controller or inverter, an equipment disconnecting means shall be provided for isolation. Where a charge control‐ ler or inverter has multiple input circuits, a single equipment disconnecting means shall be permitted to isolate the equip‐ ment from the input circuits.

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Location. Isolating devices or equipment disconnectingmeans shall be installed in circuits connected to equipment at a location within the equipment, or within sight and within 3 m (10 ft) of the equipment. An equipment disconnecting means shall be permitted to be remote from the equipment where the equipment disconnecting means can be remotely operated from within 3 m (10 ft) of the equipment.N
Interrupting Rating. An equipment disconnecting means shall have an interrupting rating sufficient for the maximum short-circuit current and voltage that is available at the termi‐ nals of the equipment. An isolating device shall not be required to have an interrupting rating.N
Isolating Device. An isolating device shall not be required to simultaneously disconnect all current-carrying conductors of a circuit. The isolating device shall be one of the following:
1. A connector meeting the requirements of 690.33 and listed and identified for use with specific equipment
2. A finger safe fuse holder
3. An isolating switch that requires a tool to open
4. An isolating device listed for the intended application
An isolating device shall be rated to open the maximum circuit current under load or be marked “Do Not Disconnect Under Load” or “Not for Current Interrupting.”N
Equipment Disconnecting Means. An equipment discon‐ necting means shall simultaneously disconnect all current- carrying conductors that are not solidly grounded of the circuit
to which it is connected. An equipment disconnecting means shall be externally operable without exposing the operator to contact with energized parts, shall indicate whether in the open (off) or closed (on) position, and shall be lockable in accordance with 110.25. An equipment disconnecting means shall be one of the following devices:
1. A manually operable switch or circuit breaker
2. A connector meeting the requirements of 690.33(E)(1)
3. A load break fused pull out switch
4. A remote-controlled circuit breaker that is operable locally and opens automatically when control power is interrupted

For equipment disconnecting means, other than those complying with 690.33, where the line and load terminals can be energized in the open position, the device shall be marked in accordance with the warning in 690.13(B).

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Part IV. Wiring Methods

690.31 Methods Permitted.

Wiring Systems. All raceway and cable wiring methods included in this Code, other wiring systems and fittings specifi‐ cally listed for use on PV arrays, and wiring as part of a listed system shall be permitted. Where wiring devices with integral enclosures are used, sufficient length of cable shall be provided to facilitate replacement.Where PV source and output circuits operating at voltages greater than 30 volts are installed in readily accessible loca‐ tions, circuit conductors shall be guarded or installed in Type MC cable or in raceway. For ambient temperatures exceeding 30°C (86°F), conductor ampacities shall be correc‐ ted in accordance with Table 690.31(A).•
Identification and Grouping. PV source circuits andPV output circuits shall not be contained in the same raceway, cable tray, cable, outlet box, junction box, or similar fitting as conductors, feeders, branch circuits of other non-PV systems, or inverter output circuits, unless the conductors of the differ‐ ent systems are separated by a partition. PV system circuit conductors shall be identified and grouped as required by 690.31(B)(1) through (2). The means of identification shall be permitted by separate color coding, marking tape, tagging, or other approved means.
1. Identification. PV system circuit conductors shall be iden‐ tified at all accessible points of termination, connection, and splices.Exception: Where the identification of the conductors is evident by spac‐ing or arrangement, further identification shall not be required.The means of identification shall be permitted by separate color coding, marking tape, tagging, or other approved means. Only solidly grounded PV system circuit conductors, in accord‐ ance with 690.41(A)(5), shall be marked in accordance with 200.6.
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2. Grouping. Where the conductors of more than one
PV system occupy the same junction box or raceway with a removable cover(s), the ac and dc conductors of each system shall be grouped separately by cable ties or similar means at least once and shall then be grouped at intervals not to exceed1.8 m (6 ft).Exception: The requirement for grouping shall not apply if the circuit enters from a cable or raceway unique to the circuit that makes the grouping obvious.
Single-Conductor Cable.(1) General. Single-conductor cable Type USE-2 and single- conductor cable listed and identified as photovoltaic (PV) wire shall be permitted in exposed outdoor locations in PV source circuits within the PV array. PV wire shall be installed in accordance with 338.10(B)(4)(b) and 334.30.
- (2) Cable Tray. PV source circuits and PV output circuitsusing single-conductor cable listed and identified as photovoltaic (PV) wire of all sizes, with or without a cable tray marking/rating, shall be permitted in cable trays installed in outdoor locations, provided that the cables are supported at intervals not to exceed 300 mm (12 in.) and secured at intervals not to exceed 1.4 m (41∕2 ft).Informational Note: Photovoltaic wire and PV cable have a nonstandard outer diameter. Table 1 of Chapter 9 contains the allowable percent of cross section of conduit and tubing for conductors and cables.(D) Multiconductor Cable.Jacketed multiconductor cable assemblies listed and identified for the application shall be permitted in outdoor locations. The cable shall be secured at intervals not exceeding 1.8 m (6 ft).
  N Table 690.31(A) Correction Factors
  Temperature Rating of ConductorAmbient Temperature60°C75°C90°C105°CAmbient Temperature(°C)(140°F)(167°F)(194°F)(221°F)(°F)301.001.001.001.008631–350.910.940.960.9787–9536–400.820.880.910.9396–10441–450.710.820.870.89105–11346–500.580.750.820.86114–12251–550.410.670.760.82123–13156–60—0.580.710.77132–14061–70—0.330.580.68141–15871–80——0.410.58159–176
  1. Flexible Cords and Cables Connected to Tracking PV Arrays. Flexible cords and flexible cables, where connec‐ ted to moving parts of tracking PV arrays, shall comply with Article 400 and shall be of a type identified as a hard service cord or portable power cable; they shall be suitable for extra- hard usage, listed for outdoor use, water resistant, and sunlight resistant. Allowable ampacities shall be in accordance with
    1. Conduit bodies in which any of the available conduit openings are unused
    2. Marking and Labeling Methods and Locations. The labels or markings shall be visible after installation. The labels shall be reflective, and all letters shall be capitalized and shall be a minimum height of 9.5 mm (3∕8 in.) in white on a red back‐
    400.5. Stranded copper PV wire shall be permitted to be connected to moving parts of tracking PV arrays in accordance with the minimum number of strands specified in Table 690.31(E).•
  2. Small-Conductor Cables. Single-conductor cables listed

for outdoor use that are sunlight resistant and moisture resist‐ ant in sizes 16 AWG and 18 AWG shall be permitted for module interconnections where such cables meet the ampacity require‐ ments of 400.5. Section 310.15 shall be used to determine the cable ampacity adjustment and correction factors.

(G)

Photovoltaic System Direct Current Circuits on or in a Building. Where PV system dc circuits run inside a building, they shall be contained in metal raceways, Type MC metal-clad cable that complies with 250.118(10), or metal enclosures from the point of penetration of the surface of the building to the first readily accessible disconnecting means. The disconnecting means shall comply with 690.13(B) and (C) and 690.15(A) and (B). The wiring methods shall comply with the additional installation requirements in 690.31(G)(1) through (4).

Embedded in Building Surfaces. Where circuits are embedded in built-up, laminate, or membrane roofing materi‐ als in roof areas not covered by PV modules and associated equipment, the location of circuits shall be clearly marked using a marking protocol that is approved as being suitable for continuous exposure to sunlight and weather.
Flexible Wiring Methods. Where flexible metal conduit (FMC) smaller than metric designator 21 (trade size 3∕4) or Type MC cable smaller than 25 mm (1 in.) in diameter contain‐ ing PV power circuit conductors is installed across ceilings or floor joists, the raceway or cable shall be protected by substan‐ tial guard strips that are at least as high as the raceway or cable. Where run exposed, other than within 1.8 m (6 ft) of their connection to equipment, these wiring methods shall closely follow the building surface or be protected from physical damage by an approved means.
Marking and Labeling Required. The following wiring methods and enclosures that contain PV system dc circuit conductors shall be marked with the wording WARNING: PHOTOVOLTAIC POWER SOURCE by means of permanently affixed labels or other approved permanent marking:

Exposed raceways, cable trays, and other wiring methods
Covers or enclosures of pull boxes and junction boxes

PV Wire AWG	Minimum Strands
18	17
16–10	19
8–4	49
2	130
1 AWG–1000 MCM	259

N Table 690.31(E) Minimum PV Wire Strands

ground. PV system dc circuit labels shall appear on every

section of the wiring system that is separated by enclosures, walls, partitions, ceilings, or floors. Spacing between labels or markings, or between a label and a marking, shall not be more than 3 m (10 ft). Labels required by this section shall be suita‐ ble for the environment where they are installed.

Flexible, Fine-Stranded Cables. Flexible, fine-stranded cables shall be terminated only with terminals, lugs, devices, or connectors in accordance with 110.14.
Bipolar Photovoltaic Systems. Where the sum, without consideration of polarity, of the voltages of the two monopole subarrays exceeds the rating of the conductors and connected equipment, monopole subarrays in a bipolar PV system shall be physically separated, and the electrical output circuits from each monopole subarray shall be installed in separate raceways until connected to the inverter. The disconnecting means and overcurrent protective devices for each monopole subarray output shall be in separate enclosures. All conductors from each separate monopole subarray shall be routed in the same raceway. Solidly grounded bipolar PV systems shall be clearly marked with a permanent, legible warning notice indicating that the disconnection of the grounded conductor(s) may result in overvoltage on the equipment.

Exception: Listed switchgear rated for the maximum voltage between circuits and containing a physical barrier separating the disconnecting means for each monopole subarray shall be permitted to be used instead of disconnecting means in separate enclosures.

690.32 Component Interconnections. Fittings and connectors

that are intended to be concealed at the time of on-site assem‐ bly, where listed for such use, shall be permitted for on-site interconnection of modules or other array components. Such fittings and connectors shall be equal to the wiring method employed in insulation, temperature rise, and fault-current withstand, and shall be capable of resisting the effects of the environment in which they are used.

Connectors. Connectors, other than those covered by 690.32, shall comply with 690.33(A) through (E).
1. Configuration. The connectors shall be polarized and shall have a configuration that is noninterchangeable with receptacles in other electrical systems on the premises.
2. Guarding. The connectors shall be constructed and instal‐ led so as to guard against inadvertent contact with live parts by persons.
3. Type. The connectors shall be of the latching or locking type. Connectors that are readily accessible and that are used in circuits operating at over 30 volts dc or 15 volts ac shall require a tool for opening.
4. Grounding Member. The grounding member shall be the first to make and the last to break contact with the mating connector.
5. Interruption of Circuit. Connectors shall be either (1) or (2):
  1. Be rated for interrupting current without hazard to the operator.
  2. Be a type that requires the use of a tool to open and marked “Do Not Disconnect Under Load” or “Not for Current Interrupting.”
Access to Boxes. Junction, pull, and outlet boxes loca‐ ted behind modules or panels shall be so installed that the wiring contained in them can be rendered accessible directly or by displacement of a module(s) or panel(s) secured by removable fasteners and connected by a flexible wiring system.

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Part V. Grounding and Bonding

690.41 System Grounding.

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(A) PV System Grounding Configurations. One or more of

2-wire PV arrays with one functional grounded conductor
Bipolar PV arrays according to 690.7(C) with a functional ground reference (center tap)

the following system grounding configurations shall be employed:

PV arrays not isolated from the grounded inverter output circuitarraysarrays
Ungrounded PVless of voltage. Equipment grounding conductors and devices shall comply with 690.43(A) through (C).
1. Photovoltaic Module Mounting Systems and Devices. Devices and systems used for mounting PV modules that are also used for bonding module frames shall be listed, labeled, and identified for bonding PV modules. Devices that mount adjacent PV modules shall be permitted to bond adjacent PV modules.
2. Equipment Secured to Grounded Metal Supports. Devices listed, labeled, and identified for bonding and ground‐ ing the metal parts of PV systems shall be permitted to bond the equipment to grounded metal supports. Metallic support structures shall have identified bonding jumpers connected between separate metallic sections or shall be identified for equipment bonding and shall be connected to the equipment grounding conductor.
3. With Circuit Conductors. Equipment grounding conduc‐ tors for the PV array and support structure (where installed) shall be contained within the same raceway, cable, or otherwise run with the PV array circuit conductors when those circuit conductors leave the vicinity of the PV array.•
  1. Size of Equipment Grounding Conductors. Equip‐ment grounding conductors for PV source and PV output
Solidly grounded PVExceptionas permitted in 690.41(B)circuits shall be sized in accordance with 250.122. Where no overcurrent protective device is used in the circuit, an assumed
PV systems that use other methods that accomplish equiv‐

alent system protection in accordance with 250.4(A) with equipment listed and identified for the use

Ground-Fault Protection. DC PV arrays shall be provided with dc ground-fault protection meeting the requirements of 690.41(B)(1) and (2) to reduce fire hazards.Exception: PV arrays with not more than two PV source circuits and with all PV system dc circuits not on or in buildings shall be permitted without ground-fault protection where solidly grounded.
1. Ground-Fault Detection. The ground fault protective device or system shall detect ground fault(s) in the PV array dc current–carrying conductors and components, including any functional grounded conductors, and be listed for providing PV ground-fault protection.•
2. Isolating Faulted Circuits. The faulted circuits shall be

(1) The current-carrying conductors of the faulted circuit

shall be automatically disconnected.

isolated by one of the following methods:

(2) The inverter or charge controller fed by the faulted circuit shall automatically cease to supply power to output circuits and isolate the PV system dc circuits from the ground reference in a functional grounded system.

•

690.42 Point of System Grounding Connection. Systems with

For solidly grounded PV systems, as permitted in 690.41(A)

(5), the grounded conductor shall be connected to a ground‐ ing electrode system by means of a grounding electrode conductor sized in accordance with 250.166.

a ground-fault protective device in accordance with 690.41(B) shall have any current-carrying conductor-to-ground connec‐ tion made by the ground-fault protective device. For solidly grounded PV systems, the dc circuit grounding connection

overcurrent device rated in accordance with 690.9(B) shall be used when applying Table 250.122. Increases in equipment grounding conductor size to address voltage drop considera‐ tions shall not be required. An equipment grounding conduc‐ tor shall not be smaller than 14 AWG.

Array Equipment Grounding Conductors. For PV modules, equipment grounding conductors smaller than 6 AWG shall comply with 250.120(C).•
Grounding Electrode System.

Buildings or Structures Supporting a PV Array. A building or structure supporting a PV array shall have a grounding elec‐ trode system installed in accordance with Part III of Article 250.PV array equipment grounding conductors shall be connec‐ ted to the grounding electrode system of the building or struc‐ ture supporting the PV array in accordance with Part VII of Article 250. This connection shall be in addition to any other equipment grounding conductor requirements in 690.43(C). The PV array equipment grounding conductors shall be sized in accordance with 690.45.For PV systems that are not solidly grounded, the equipment grounding conductor for the output of the PV system, connec‐ ted to associated distribution equipment, shall be permitted to be the connection to ground for ground-fault protection and equipment grounding of the PV array.
- shall be made at any single point on the PV output circuit.
Informational Note: Most PV systems installed in the pastdecade are actually functional grounded systems rather than solidly grounded systems as defined in this Code. For functional grounded PV systems with an interactive inverter output, the ac equipment grounding conductor is connected to associated grounded ac distribution equipment. This connection is often690.43 Equipment Grounding and Bonding. Exposed non– current-carrying metal parts of PV module frames, electrical equipment, and conductor enclosures of PV systems shall be grounded in accordance with 250.134 or 250.136(A), regard‐

the connection to ground for ground-fault protection andequipment grounding of the PV array.N
Additional Auxiliary Electrodes for Array Grounding. Grounding electrodes shall be permitted to be installed in accordance with 250.52 and 250.54 at the location of ground- and roof-mounted PV arrays. The electrodes shall be permitted to be connected directly to the array frame(s) or structure. The grounding electrode conductor shall be sized according to

250.66. The structure of a ground-mounted PV array shall be permitted to be considered a grounding electrode if it meets the requirements of 250.52. Roof mounted PV arrays shall be permitted to use the metal frame of a building or structure if the requirements of 250.52(A)(2) are met.

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Equipment Bonding Jumpers. Equipment bondingjumpers, if used, shall comply with 250.120(C).
Part VI. Marking
Modules. Modules shall be marked with identification of terminals or leads as to polarity, maximum overcurrent device rating for module protection, and with the following ratings:
1. Open-circuit voltage
2. Operating voltage
3. Maximum permissible system voltage
4. Operating current
5. Short-circuit current
6. Maximum power
Alternating-Current Photovoltaic Modules. Alternating-current modules shall be marked with identifica‐ tion of terminals or leads and with identification of the follow‐ ing ratings:
1. Nominal operating ac voltage
2. Nominal operating ac frequency
3. Maximum ac power
4. Maximum ac current
5. Maximum overcurrent device rating for ac module protection
1. Maximum voltageInformational Note to (1): See 690.7 for voltage.
2. Maximum circuit currentInformational Note to (2): See 690.8(A) for calculation of maxi‐ mum circuit current.
3. Maximum rated output current of the charge controller or dc-to-dc converter (if installed)
Direct-Current Photovoltaic Power Source. A perma‐ nent label for the dc PV power source indicating the informa‐ tion specified in (1) through (3) shall be provided by the installer at dc PV system disconnecting means and at each dc equipment disconnecting means required by 690.15. Where a disconnecting means has more than one dc PV power source, the values in 690.53(1) through (3) shall be specified for each source.
•
Interactive System Point of Interconnection. All inter‐active system(s) points of interconnection with other sources shall be marked at an accessible location at the disconnecting means as a power source and with the rated ac output current and the nominal operating ac voltage.
Photovoltaic Systems Connected to Energy Storage Systems. The PV system output circuit conductors shall be marked to indicate the polarity where connected to energy storage systems.
Identification of Power Sources.

Facilities with Stand-Alone Systems. Any structure or building with a PV power system that is not connected to a util‐ ity service source and is a stand-alone system shall have a permanent plaque or directory installed on the exterior of the building or structure at a readily visible location. The plaque or directory shall indicate the location of system disconnecting means and that the structure contains a stand-alone electrical power system.
Facilities with Utility Services and Photovoltaic Systems. Plaques or directories shall be installed in accordance with 705.10.
Buildings with Rapid Shutdown. Buildings with PV systems shall have permanent labels as described in 690.56(C) (1) through (C)(3).N
1. Rapid Shutdown Type. The type of PV system rapid shut‐ down shall be labeled as described in 690.56(C)(1)(a) or (1)(b):
  1. For PV systems that shut down the array and conduc‐ tors leaving the array:SOLAR PV SYSTEM IS EQUIPPED WITH RAPID SHUT‐DOWN.TURN RAPID SHUTDOWN SWITCH TO THE “OFF” POSI‐ TION TO SHUT DOWN PV SYSTEM AND REDUCE SHOCK HAZARD IN ARRAY.The title “SOLAR PV SYSTEM IS EQUIPPED WITH RAPIDSHUTDOWN” shall utilize capitalized characters with a mini‐ mum height of 9.5 mm (3∕8 in.) in black on yellow background, and the remaining characters shall be capitalized with a mini‐ mum height of 4.8 mm (3∕16 in.) in black on white background. [See Figure 690.56(C)(1)(a).]
  2. For PV systems that only shut down conductors leav‐ ing the array:SOLAR PV SYSTEM IS EQUIPPED WITH RAPID SHUT‐DOWNTURN RAPID SHUTDOWN SWITCH TO THE “OFF” POSI‐ TION TO SHUT DOWNCONDUCTORS OUTSIDE THE ARRAY. CONDUCTORS IN ARRAY REMAINENERGIZED IN SUNLIGHT.The title “SOLAR PV SYSTEM IS EQUIPPED WITH RAPIDSHUTDOWN” shall utilize capitalized characters with a mini‐ mum height of 9.5 mm (3∕8 in.) in white on red background, and the remaining characters shall be capitalized with a mini‐ mum height of 4.8 mm (3∕16 in.) in black on white background. [See Figure 690.56(C)(1)(b).]The labels in 690.56(C)(1)(a) and (b) shall include a simple diagram of a building with a roof. The diagram shall have sections in red to signify sections of the PV system that are not shut down when the rapid shutdown switch is operated.The rapid shutdown label in 690.56(C)(1) shall be located on or no more than 1 m (3 ft) from the service disconnecting means to which the PV systems are connected and shall indi‐690.56 ARTICLE 691 — LARGE-SCALE PHOTOVOLTAIC (PV) ELECTRIC POWER PRODUCTION FACILITY
    SOLAR PV SYSTEM EQUIPPED WITH RAPID SHUTDOWNTURN RAPID SHUTDOWN SWITCH TO THE“OFF” POSITION TO SHUT DOWN PV SYSTEM AND REDUCESHOCK HAZARDIN THE ARRAY.SOLAR ELECTRIC PV PANELSPart VII. Connection to Other SourcesN690.59 Connection to Other Sources. PV systems connected to other sources shall be installed in accordance with Parts I and II of Article 705.•
    Part VIII. Energy Storage Systems
    1. General. An energy storage system connected to a PV system shall be installed in accordance with Article 706.•
    2. Self-Regulated PV Charge Control. The PV source
    circuit shall be considered to comply with the requirements of 706.23 if:
    N FIGURE 690.56(C)(1)(a) Label for PV Systems that Shut Down the Array and the Conductors Leaving the Array.
    cate the location of all identified rapid shutdown switches if not at the same location.N
2. Buildings with More Than One Rapid Shutdown Type. For buildings that have PV systems with both rapid shutdown types or a PV system with a rapid shutdown type and a PV system with no rapid shutdown, a detailed plan view diagram of the roof shall be provided showing each different PV system and a dotted line around areas that remain ener‐ gized after the rapid shutdown switch is operated.N
3. Rapid Shutdown Switch. A rapid shutdown switch shall have a label located on or no more than 1 m (3 ft) from the switch that includes the following wording: