Three-Phase Power

Three-phase power is an electrical service that uses three alternating currents offset by 120 degrees, delivering more consistent and higher-capacity power than single-phase. It is standard for commercial and industrial buildings but uncommon in residential homes in the United States.

Three-phase power is occasionally found in larger residences, farms, or homes with commercial-grade equipment (like large workshops or agricultural operations). Solar installations on three-phase properties require a three-phase inverter or multiple single-phase inverters balanced across all three phases. Three-phase inverters are more common in commercial solar and are typically available in larger sizes (10 kW and above). If your property has three-phase service and you’re installing residential solar, make sure your installer is aware — using a single-phase inverter on a three-phase service may require load balancing and could affect utility interconnection requirements. The cost difference is usually minimal, but the equipment selection and system design must account for the three-phase configuration to ensure code compliance and proper grid connection.