California Reaches Clean Energy Milestone as Solar Overtakes Natural Gas on the Grid

California has achieved a significant clean energy milestone, with solar power surpassing natural gas as the leading source of electricity generation on the state’s main power grid during the first five months of 2026. The development marks an important step in the state’s transition toward a lower-carbon energy system and highlights the growing impact of renewable energy investments.

According to data from the California Independent System Operator (CAISO), utility-scale solar generation increased by 21% compared to the same period in 2024, while electricity produced from natural gas fell by 60%. Solar power generated more electricity than natural gas on 82% of days between January and May 2026, a sharp rise from just 21% of days during the same period in 2024 and 2025.

The shift has been driven by substantial growth in renewable energy infrastructure. Utility-scale solar capacity expanded by 19% over the past two years, reaching 25 gigawatts (GW), while battery storage capacity surged by 79% to 16 GW. Overall grid capacity increased by approximately 11 GW, strengthening California’s ability to integrate more clean energy resources.

Battery storage has become a critical component of the state’s electricity system, storing surplus solar energy generated during daylight hours and delivering it back to the grid during evening and early morning periods when demand remains high. As a result, battery contributions to the grid during the first five months of 2026 were three times higher than in the corresponding period of 2024.

Despite a 7% increase in electricity demand, net generation within the CAISO system declined by 19%, with the difference largely met through increased electricity imports from neighboring regions. Improved hydropower availability in the Pacific Northwest and additional wind energy imports have helped support grid reliability.

The milestone underscores how expanding solar generation, growing energy storage capacity, and regional power connectivity are reshaping California’s electricity mix and accelerating the state’s clean energy transition.

Solar overtaking gas in California is a real inflection, and it changes what corporates operating in the state can genuinely claim in Scope 2 disclosure. Our energy-transition and climate-action teams help clients evaluate what these dispatch dynamics mean for Scope 2 disclosure narrative.