CAISO: California Independent System Operator
CAISO operates California's electricity grid and wholesale market, serving approximately 80% of the state's load. As a global leader in clean energy policy, California is driving toward 100% clean electricity by 2045.
Source: CAISO
Last updated: December 22, 2024
Coverage Area
CAISO serves the majority of California, including the state's largest utilities: Pacific Gas & Electric (PG&E), Southern California Edison (SCE), and San Diego Gas & Electric (SDG&E). Some areas, including Los Angeles Department of Water and Power (LADWP) and Sacramento Municipal Utility District (SMUD), operate outside CAISO but coordinate closely.
Clean Energy Policy Leadership
California has the most aggressive clean energy mandates in the nation. SB 100 requires 100% clean electricity by 2045, with interim targets of 60% renewable by 2030. The state's Renewable Portfolio Standard (RPS) has driven massive investment in solar, wind, and increasingly battery storage.
The Duck Curve Challenge
CAISO pioneered identification of the "duck curve"—the pattern created when abundant midday solar production drives net load down, followed by a steep evening ramp as solar fades and demand peaks. This challenge has driven California to become the global leader in grid-scale battery storage deployment.
Battery storage now exceeds 10 GW in California, providing critical evening peak capacity and enabling higher solar penetration. Storage has repeatedly proven essential during heat waves and reliability events.
Offshore Wind Development
California is developing floating offshore wind projects along its coast, with targets of 25 GW by 2045. The Morro Bay and Humboldt wind energy areas have been leased, with projects expected online in the early 2030s. Offshore wind will complement solar by generating power during evening hours and winter months.
Extended Day-Ahead Market (EDAM)
CAISO is expanding its Western Energy Imbalance Market (WEIM) with the Extended Day-Ahead Market, which will enable day-ahead trading across much of the Western Interconnection. This expansion will improve renewable integration and reduce costs through regional coordination.
State Guide in CAISO
Frequently Asked Questions
What is the duck curve?
The duck curve describes the pattern of net load (demand minus solar generation) that dips during midday when solar is abundant, then rises steeply in the evening as solar fades. Managing this ramp requires flexible resources like batteries and demand response.
Why is California leading in battery storage?
California's aggressive clean energy policies, combined with the duck curve challenge, have driven massive storage deployment. State mandates and utility procurement requirements accelerated the market, making California home to over half of US grid storage capacity.
How will offshore wind change CAISO?
Offshore wind will provide generation during evening hours and winter months when solar is less productive, helping balance the grid and reduce reliance on natural gas for evening peaks.