California Utility-Scale Battery Storage Capacity

## What this measures

The nameplate power capacity, in gigawatts, of utility-scale battery storage operating in California at each month's end.

## Why it matters

Batteries are the fastest-growing kind of power capacity on the U.S. grid. They store midday solar output for the evening peak, steady the grid as demand from data centers and electrification grows, and make a direct, monthly read of the build-out that tax credits, falling cell prices and interconnection queues drive.

## How to read it

California’s capacity was 16.0 GW in July 2026, against 13.4 GW a year earlier. At the end of each year it was 4.9 GW in 2022, 8.0 GW in 2023, 11.8 GW in 2024 and 14.7 GW in 2025. California had the most battery capacity of any state until Texas passed it in January 2026. Higher means more storage on the grid. The line rarely falls, because units are seldom retired, so read the pace: the gigawatts added over twelve months. Read with planned additions (energy.battery_storage.planned_12m_gw.us) and U.S. lithium-ion battery imports (trade.li_ion_batteries.us_imports).

## What it does not say

This is power, not energy: gigawatts say how fast the batteries can discharge, not for how many hours. It counts utility-scale units at plants of 1 MW or more; home, business and other small batteries are left out. Only units reported as operating count, not those on standby or out of service. EIA-860M is preliminary: EIA revises it, and the annual EIA-860 survey later replaces it, so recent months can change.

## How it's built

EIA's monthly generator inventory lists every operable generator. Palanor sums the nameplate capacity of each unit with technology "Batteries" and status "operating" located in California, month by month from January 2010, and converts megawatts to gigawatts. Weekly runs re-read the last 13 months so revisions carry through.

## Source

U.S. Energy Information Administration, Form EIA-860M Preliminary Monthly Electric Generator Inventory, via the EIA Open Data API (electricity/operating-generator-capacity). EIA data are in the public domain.