Photovoltaic Systems are provided as utility-interactive or stand-alone power supply systems. NEC Code 690 covers details about PV installations.
NEC 690.2 covers the definition details of PV equipment including Bipolar arrays, Inverts, Charge Controllers, Solar cells
NEC 690.4 provides details about PV Installation. PV systems are permitted to supply power to buildings or other structures along with other sources of power supply systems. PV source circuits (conductors connected to PV arrays) and PV output circuits (conductors connected between inverter & load) shall not be provided in the same raceways, cable tray, outlet, or junction boxes where non-PV system conductors, feeders, and branch circuits are routed. If it has to be provided it shall be done with proper partition. NEC 690.4(B) covers details about PV circuit identification and grouping details. PV source and Inverter circuits shall be identified at all points of conductors or circuit terminations, connections, and splices. In the case of conductors, more than one PV system is to be routed in the same junction box, raceway, or equipment, then conductors of each PV system are identified at terminations, connections, and splices. Suppose the conductors of multiple PV systems are routed through the same raceways or junction boxes with removable covers. In that case, the conductors (a.c and d.c) are to be grouped separately with wire ties at an interval not exceeding 1.8 mts (6 ft) in length.
NEC 690.4(C) requires that a jumper is to be provided between the PV source circuit and the module terminal or panel such that the PV module or panel can be removed from the PV source circuit without interrupting the ground connections to the PV source circuit.
NEC 690.4(D) requires that equipment such as Inverters, PV modules, PV panels, motor generators, and other equipment shall be identified and listed for PV power system application. The equipment listed for mobile, telecommunication, marine, or other applications shall not be used for permanent PV installations.
NEC 690.4(E) requires that PV equipment & systems and associated wiring & connection installations shall be carried out by qualified persons
NEC 690.4(F) covers circuit routing details of PV source and inverter output conductors. In case of circuits routing through embedded in built-up, laminate, or membrane roofing materials in the roof areas not covered by PV equipment or modules, the location of the PV circuit conductors shall be clearly marked
NEC 690.4(G) covers details related to Bipolar PV systems. In the case of monopole subarrays of the bipolar PV system whose sum of voltages without considering the polarity is greater than the rating of the connected conductors, equipment shall be physically separated. Electrical output circuit conductors of each monopole subarray system shall be routed through separate raceways until connected to the inverter. The disconnecting means and over current protection devices of each PV monopoly subarray output system shall be provided in separate enclosures. All the PV source circuit conductors connected from separate monopole subarrays shall be routed through the same raceways
NEC 690.4(H) covers details about the installation of multiple inverters in the PV system. Multiple utility interactive inverters of the PV system can be installed in a single building or structure. In case of inverters located remotely from each other, a directory is to be provided in accordance with 705.10
NEC 690.5 covers details about the provision of Ground Fault Protection for PV systems. A Ground Fault Current Interruption (GFCI) is intended for the protection of personnel in single-phase ac systems against electric shocks. GFCI opens the ungrounded conductors in case of a fault (5 mA fault current) is detected. Ground Fault Protection in the case of PV systems is intended to prevent fires in dc PV circuits due to earth faults. NEC 690.5(A) covers Ground fault detection & interruption system. In case of any ground fault, the GFCI device is permitted to open the grounded conductor of the fault circuit for clearing the fault. In this case, all the conductors of the faulted circuits shall be opened automatically and simultaneously. This clause also requires that the manual opening of PV dc disconnections shall not result in the operation of the GFCI device or result in an opening in any grounded conductors. NEC 690.5(B) covers the methods to isolate the faulted circuits. Faulted circuits can be isolated by automatically disconnecting all ungrounded conductors of faulted circuits or by automatically cutting power supply to PV output circuits fed from an inverter or charge controller. Typically, a GFCI device operating in a PV system with a voltage rating of 48V or less automatically disconnects the ungrounded conductors using a circuit breaker. In the case of PV systems with a voltage greater than 48V, the GFCI device automatically trips off connected equipment when a ground fault is detected.
NEC 690.6 covers alternating current modules of a PV system. AC module consists of inverters and circuit conductors. Inverter output circuits are considered as the output of the ac modules. NEC 690.6(C) specifies that a single disconnecting means is permitted for the combined output of one or more ac output modules. In addition, each ac module in multiple ac module systems is provided with a connector, bolted or terminal type disconnecting means. NEC 690.6D) permits ac module systems to use a single detection device for the detection of ground faults to disable the array by removing ac power to ac modules.