Where to find NEC guidelines specific to solar installations?

Finding NEC Guidelines

To find NEC guidelines specific to solar installations, visit the National Fire Protection Association (NFPA) website at nfpa.org. From there, navigate to “Codes and Standards” and select “NEC” to access the most recent editions and articles relevant to solar installations. You can also purchase a physical copy of the NEC codebook from the NFPA website or other online retailers.

Understanding NEC Articles 690 and 705

NEC Article 690 covers the installation and safety requirements for solar photovoltaic (PV) systems, while Article 705 addresses the installation and safety requirements for interconnecting PV systems to the utility grid. When designing solar installations, it’s essential to understand the requirements outlined in these articles, including the maximum allowable PV array size, PV system disconnect requirements, and electrical connection requirements.

Solar Breaker Sizing

When sizing breakers for solar installations, NEC 705.12(B) requires that the maximum PV array output be limited to the rating of the overcurrent protective device (OCPD). For example, if a PV array produces a maximum of 12,000 watts (12 kW) of power, the OCPD rating should be 150 amps (12 kW / 80% of the array’s maximum DC output voltage). The NEC also requires that the OCPD rating be calculated based on the PV system’s DC output voltage, which can be found in the PV panel data sheet. By following these guidelines, solar installers can ensure that their PV systems are safely and properly sized for optimal performance and reliability.