Important: Other than a Dwelling Unit, an electrical engineer’s signature and seal is required for any photovoltaic (PV) system to be installed. A structural engineer’s signature and seal is required for PV modules to be installed. If the letter states that the trusses need to be structurally reinforced to handle the additional weight then a Building Permit is required, if no reinforcing is required then a Building Permit can be submitted and only electrical inspections will be performed.
PV system submittal must include all of the following:
- Manufacturer’s specs for ALL PV equipment, including listing, nameplate short-circuit current (Isc) and open-circuit voltage (Voc) for modules, and direct current (DC) listing for fuses and circuit breakers used in DC circuits. NOTE: Fuses and circuit breakers listed for use in Automobile, Marine, or telecom applications are NOT acceptable.
- Calculations: Conductor ampacity = Module nameplate Isc X 156% X the temperature derating factor from National Electrical Code (NEC) table 690.31(C). NOTE: Temperature derating shall apply to all conductors installed in areas with high ambient temperatures (such as rooftops or in attics). For conductors in conduit and cables connecting PV modules assume an ambient temperature of 65°C where there is cooling air available at the back of the modules (minimum of 6” clearance to rooftop) and 75°C where clearance is less than 6”.
- Fuses and circuit breakers shall be sized @ Isc X 156% and shall be used in 1 amp increments up to 15 amps. Devices exceeding 15 amps shall use the next standard size. NOTE: In no case shall the overcurrent protection (OCP) device rating exceed the calculated conductor ampacity.
- One-line Diagram: Shall include all of the following:
- Conductor sizes and types
- Conduit sizes and types
- Fuse and circuit breaker ratings
- Inverter rating
- Ground fault protection device rating
- AC and DC disconnect ratings
- Electrode conductor size
- Equipment grounding conductor size
- Weight Roof Framing: Please provide by the Structure Engineer.
- Dead Load
- Snow load
- Wind load 105 mph, 3 second gust, exposure C
- Type of hardware to attach Modules/Racks