Do solar systems with battery storage require additional breakers?

Breaker Sizing Considerations

When designing a solar system with battery storage, it’s essential to consider the additional electrical load imposed by the batteries. In most cases, the breaker for the solar array and the battery charger will need to be upsized to accommodate the increased current draw. For example, a 2000-watt solar array with a 2000-watt battery charger would typically require a 50-amp breaker, whereas a standard residential electrical panel might only have 15-amp or 20-amp breakers.

National Electric Code Compliance

The National Electric Code (NEC) dictates specific requirements for breaker sizing in solar installations. According to the NEC, the ampacity of the circuit must be calculated based on the maximum current rating of the solar array and battery charger combined. For instance, if the solar array and battery charger have the same rating of 2000 watts, the total ampacity would be 2000/240V = 8.3 amps. However, to ensure safe operation, the NEC recommends increasing this value by 25% to account for inrush currents, resulting in a minimum 10.375-amp breaker.

Grounding and Bonding Considerations

In addition to breaker sizing, solar systems with battery storage also require careful attention to grounding and bonding. This includes ensuring that the solar array and battery charger are properly grounded to the electrical panel, and that the electrical panel is bonded to the grounding system. Failure to comply with these requirements can lead to electrical shock or fire hazards. As a general rule, it’s recommended to have at least a 6’ grounding electrode system that is bonded to the electrical panel and solar array.