The State of California, the California Independent System Operator (CAISO) and renewable energy advocates take great pride in the growth of renewable generation in the California market, as illustrated in the Facebook posts highlighted in our commentary “California Dreaming”. California has committed to achieve 60% renewable generation by 2030 and 100% renewable plus zero emissions generation by 2045.

The image below shows the CAISO electric generation “fuel” mix over a 6-day period from March 12th – 17th, 2026. There is substantial, reasonably consistent solar generation on each day during the period. Wind generation is inconsistent with greatest wind generation on the weekend nights, the 14th & 15th. Battery storage contributes each day during the early morning and early evening “duck peak” periods. Overnight demand is met primarily by natural gas, imports, storage and large hydro. Nuclear, geothermal, biomass, biogas, and small hydro contribute consistently throughout the period. 

California has an installed utility-scale generating capacity of approximately 50 GW. CAISO does not identify a contribution by behind-the-meter solar generation in the image below, though that source represents a generating capacity of approximately 20 GW, approximately equal to the generator output shown in the image below.

CAISO achieves approximately 48% renewable generation on 3/17 as shown in the image below. Solar generated approximately 200 GWh and wind generated approximately 50 GWh, while natural gas and electricity imports represented approximately 125 GWh each for the day. Batteries delivered approximately 50 GWh, approximately 5 GWh in the early morning and approximately 45 GWh in the early evening. 

Solar generation would be required to increase by approximately 6 GW to displace the natural gas and imported generation during the period when solar is available, or by approximately 75 GWh; and, by approximately 7 GW or 85 GWh to achieve the 60% renewable percentage required by 2030.

Solar generation would be required to increase by approximately 25 GW and 250 GWh or approximately 125% to displace all of the natural gas generated and imported electricity required to meet demand on 3/17 and storage would be required to increase by approximately 100 GW or 400 GWh or 800% to time shift the additional solar energy generation to the period when solar generation is insufficient.

The calculations above are based on this one particular day, which is reasonably representative of typical seasonal conditions. The storage calculation assumes that sufficient solar generator output would occur on the next day to recharge storage. If that were not the case, storage w2ould need to increase by approximately 400 GWh for each succeeding day with no solar output and solar generator capacity would be required to increase by approximately 50 GW for each potential successive day with no solar contribution to fully recharge storage over the same number of days over which it was discharged.

CAISO is close to achieving its required 60% renewable generation by 2030. Irt currently lacks sufficient storage capacity to avoid curtailment of solar and wind generation, as it curtailed up to 2 GW of solar generation from 7 am to 6 pm on 3/17.  However, CAISO is a long way from a freestanding, reliable renewable plus zero emissions grid.