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PHOTOVOLTAIC ELECTRICAL POWER SYSTEMS INSPECTOR/INSTALLER CHECKLIST 1 of 7

PHOTOVOLTAIC ELECTRICAL POWER SYSTEMS
INSPECTOR/INSTALLER CHECKLIST


The following checklist is an outline of the general requirements found in the
2005 and 2008
National Electrical Codes (NEC) Article 690 for Photovoltaic (PV) Power Systems
installations.

The checklist is only a guide and applies to any component used or installed in a PV system
other than a listed, factory-assembled component.

The local authority having jurisdiction (AHJ) or inspector has the final say on what is or is not
acceptable. Local codes may modify the requirements of the
NEC.

This list should be used in conjunction with Article 690 and other applicable articles of the
NEC and includes inspection requirements for both stand-alone PV systems (with and without
batteries) and utility-interactive PV systems. Where Article 690 differs from other articles of
the
NEC, Article 690 takes precedence. [690.3]

References in brackets [ ] are to the 2005 and 2008
NEC and other relevant documents.
Changes related to
2008 NEC requirements are noted in {brackets}


Questions: John Wiles, Southwest Technology Development Institute, New Mexico State
University 575-646-6105 575-646-3841 FAX jwiles@nmsu.edu


Revised 6/25/08 2 of 7
CHECKLIST FOR PHOTOVOLTAIC POWER SYSTEM INSTALLATIONS

1. PV ARRAYS
PV modules listed to UL Standard 1703? [110.3] {690.4(D)}
a. Mechanical Attachment
Modules attached to the mounting structure according to the manufacturers
instructions? [110.3(B)]
Roof penetrations secure and weather tight?
b. Grounding
Each module grounded using the supplied hardware, the grounding point identified on
the module and the manufacturers instructions? Note: Bolting the module to a
grounded structure usually will not meet
NEC requirements [110.3(B)]. Array PV
mounting racks are usually not identified as equipment-grounding conductors.
Properly sized equipment-grounding conductors routed with the circuit conductors??
[690.45]

c. Conductors
Conductor type? If exposed: USE-2, UF (usually inadequate at 60°C), or SE, 90°C,
wet-rated and sunlight-resistant. [690.31(B)] {2008 NEC restricts exposed single-
conductor wiring to USE-2 and listed PV/Photovoltaic wire/cable}If in conduit: RHW-
2, THWN-2, or XHHW-2 90°C, wet-rated conductors. [310.15]
Conductor insulation rated at 90°C [UL-1703] to allow for operation at 70°C+ near
modules and in conduit exposed to sunlight (add 17-20°C to ambient temperature-
2005 NEC){see Table 310.15(B)(2) in the
2008 NEC}
Temperature-derated ampacity calculations based on 156% of short-circuit current
(Isc), and the derated ampacity greater than 156% Isc rating of overcurrent device?
[690.8,9]
Note: Suggest temperature derating factors of 65°C in installations where the backs of
the module receive cooling air (6 or more from surface) and 75°C where no cooling air
can get to the backs of the modules. Ambient temperatures in excess of 40°C may
require different derating factors.

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Portable power cords allowed only for tracker connections? [690.31(C), 400.3,7,8]
Strain reliefs/cable clamps or conduit used on all cables and cords? [300.4, 400.10]
Listed for the application and the environment?

2. OVERCURRENT PROTECTION
Overcurrent devices in the dc circuits listed for dc operation? If device not marked dc,
verify dc listing with manufacturer. Auto, marine, and telecom devices not acceptable.
Rated at 1.25 x 1.25 = 1.56 times short-circuit current from modules? [UL-1703,
690.8, module instructions] Note: Both 125% factors are now in the
NEC.
Supplementary listed devices are allowed in PV source circuits only, but branch-circuit
rated devices preferred. [690.9(C)].
Each module or series string of modules have an overcurrent device protecting the
module? [UL-1703/
NEC 110.3(B)] Note: Frequently, installers ignore this requirement
marked on the back of modules. Listed combiner PV combiner boxes meeting this
requirement are available. SMA Sunny Boy and some other string inverters
operating at high voltages may not require dc fuses with two strings of modules or
less. One or two strings of modules do not require overcurrent devices, but three
strings or more in parallel will usually require an overcurrent device.
Located in a position in the circuit to protect the module conductors from backfed
currents from parallel module circuits or from the charge controller or battery? [690-
9(A) FPN]
Smallest conductor used to wire modules protected? Sources of overcurrent are
parallel-connected modules, batteries, and ac backfeed through inverters. [690-9(A)]
User-accessible fuses in touch-safe holders or capable of being changed without
touching live contacts? [690.16]

3. ELECTRICAL CONNECTIONS
Pressure terminals tightened to the recommended torque specification?
Crimp-on terminals listed and installed with listed crimping tools by the same
manufacturer? 4 of 7
Twist-on wire connectors listed for the environment (i.e. dry, damp, wet, or direct
burial) and installed per the manufacturers instructions?
Pressure lugs or other terminals listed for the environment? (i.e. inside, outside, wet,
direct burial)
Power distribution blocks
listed and not just UL Recognized?
Terminals containing more than one conductor listed for multiple conductors?
Connectors or terminals using flexible, fine-stranded conductors listed for use with
such conductors?
Locking (tool-required) on readily accessible PV conductors operating over 30 volts
{690.33(C)}

4. CHARGE CONTROLLERS
Charge controller listed to UL Standard 1741? [110.3] {690.4(D)}
Exposed energized terminals not readily accessible?
Does a diversion controller have an independent backup control method?
[690.72(B)(1)]

5. DISCONNECTS
Disconnects listed for dc operation in dc circuits? Automotive, marine, and telecom
devices are not acceptable.
PV Disconnect readily accessible and located at first point of penetration of PV
conductors?
PV conductors outside structure until reaching first readily accessible disconnect
unless in metallic raceway? [690.14, 690.31(F)]
Disconnects for all current-carrying conductors of PV source? [690.13]
Disconnects for equipment? [690.17]
Grounded conductors
not fused or switched? Bolted disconnects OK.
Note: Listed PV Centers by Xantrex, Outback, and others for 12, 24, and 48-volt
systems contain charge controllers, disconnects, and overcurrent protection for entire
dc system with possible exception of source circuit or module protective fuses.
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6. INVERTERS (Stand-alone Systems)
Inverter listed to UL Standard 1741? [110.3] {690.4(D)} Note: Inverters listed to
telecommunications or other standards do not meet
NEC requirements.
DC input currents calculated for cable and fuse requirements? Input current = rated ac
output in watts divided by lowest battery voltage divided by inverter efficiency at that
power level. [690.8(B)(4)]
Cables to batteries sized 125% of calculated inverter input currents? [690.8(A)]
Overcurrent/Disconnects mounted near batteries and external to PV load centers if
cables are longer than 4-5 feet to batteries or inverter?
High interrupt, listed, dc-rated fuses or circuit breakers used in battery circuits?
AIR/AIC at least 20,000 amps? [690.71(C), 110.9]
No multiwire branch circuits where single 120-volt inverters connected to 120/240-volt
load centers? [100Branch Circuit, Multiwire], [690.10(C)]

7. BATTERIES

None are listed.
Building-wire type cables used? [Chapter 3] Note: Welding cables, marine, locomotive
(DLO), and auto battery cables don't meet
NEC. Flexible, listed RHW, or THW cables
are available. Article 400 flexible cables larger than 2/0 AWG are OK for battery cell
connections, but not in conduit or through walls. [690.74, 400.8] Flexible, fine stranded
cables require very limited, specially listed terminals. See stand-alone inverters for
ampacity calculations.
Access limited? [690.71(B)]
Installed in well-vented areas (garages, basements, outbuildings, and not living
areas)? Note: Manifolds, power venting, and single exterior vents to the outside are
not required and should be avoided.
Cables to inverters, dc load centers, and/or charge controllers in conduit?
Conduit enters the battery enclosure below the tops of the batteries? [300.4]
Note: There are no listed battery boxes. Lockable heavy-duty plastic polyethylene
tool boxes are usually acceptable
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8. INVERTERS (Utility-interactive Systems)
Inverter listed to UL Standard 1741 and identified for use in interactive photovoltaic
power systems? [690.4(D), 690.60] Note: Inverters listed to telecommunications and
other standards do not meet
NEC requirements.
Backup charge controller to regulate the batteries when the grid fails? [690.72(B)(1)]
Connected to dedicated branch circuit with back-fed overcurrent protection? [690.64]
Listed dc and ac disconnects and overcurrent protection? [690.15,17]
Total rating of overcurrent devices supplying power to ac load center (main breaker
plus backfed PV breaker) less than load-center rating (120% of rating in residences)?
[690.64(B)(2)]