Energy Storage System (ESS)

An Energy Storage System (ESS) is the complete battery setup that stores electricity for later use, including the battery cells, battery management system (BMS), inverter/charger, enclosure, and monitoring software. In residential solar, ESS is used interchangeably with terms like “home battery” or “solar battery system.”

An ESS paired with solar panels allows homeowners to store excess solar energy generated during the day and use it at night, during peak electricity rate periods, or during grid outages. Key specifications to compare when shopping for an ESS include: usable capacity (kWh), continuous power output (kW), peak/surge power (kW), round-trip efficiency (%), cycle life (number of charge/discharge cycles), and warranty duration. Popular residential ESS options in the US market include the Tesla Powerwall, Enphase IQ Battery, LG RESU, Franklin WH, and Generac PWRcell. As of 2026, home batteries qualify for the 30% federal tax credit when installed with or added to a solar system. The cost of residential ESS typically ranges from $10,000 to $20,000 per unit installed, and multiple units can be stacked for greater capacity.