Quick Answer
To ensure compliance with local building codes for solar, verify the system design meets the National Electric Code (NEC) and International Residential Code (IRC) requirements, and hire a licensed electrician for installation.
Understanding Solar Breaker Sizing Requirements
When designing a solar electric system, it’s essential to size the main service breaker correctly. According to the NEC, the main service breaker must be sized for the total fault current of the system, including the solar array, charge controller, inverter, and other loads. A common rule of thumb is to size the main service breaker for 125% of the inverter’s maximum DC output current.
Calculating DC Output Current
To calculate the inverter’s maximum DC output current, you’ll need to know the system’s total DC power output. This can be calculated using the solar array’s total wattage rating and the inverter’s efficiency rating. For example, if the solar array produces 5,000 watts and the inverter is 98% efficient, the inverter’s maximum DC output current would be approximately 51 amps (5,000 W / 98% * 1.25 to account for inverter and panel inefficiencies).
Local Building Code Compliance
Before installing a solar electric system, verify the design meets local building codes and regulations. This may involve hiring a licensed electrician to inspect the system and ensure compliance with the NEC and IRC. Additional requirements may include submitting plans for review and approval by local authorities, and obtaining any necessary permits or inspections before installation.
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