A battery energy storage system (BESS) is a stationary installation of batteries, inverters, and controls that stores electricity for later use. Grid-scale systems shift solar from midday to evening; behind-the-meter systems at a building or garage shave demand peaks and provide backup.
Scale and duration
- California’s grid fleet exceeded 17,000 megawatts in 2026, with most lithium-ion systems rated for four to six hours of discharge.
- Behind-the-meter storage in California reached about 1,600 megawatts at the end of 2025, and 37 percent of new rooftop solar systems now include a battery.
Why it matters for parking
A garage’s evening peak is usually a few hundred kilowatt-hours, small enough for a behind-the-meter system to cover. Inside an enclosed structure the system falls under NFPA 855, and the Moss Landing fire of January 2025 is the reference event every fire marshal has read about. Sources: CAISO; Grid Status.