California’s utility-scale PV and Concentrated Solar Power (CSP) output peaked in the afternoon of May 30th, 2014 at around 4.7 GW.

Renewable energy consultant Bernard Chabot has published his latest analysis of renewable energy in California, which shows that the state’s utility-scale solar photovoltaic (PV) plants produced 1,070 gigawatt-hours (GWh) of electricity during May 2014. Concentrating solar power (CSP) plants produced another 114 GWh.

This means that utility-scale PV met 5.4% of the state’s electricity demand during the month, with CSP meeting another 0.6%. When all renewable energy sources including wind, hydro, geothermal and biomass are included, utility-scale renewable energy met 28% of the state’s electricity demand in May 2014.

Chabot’s analysis is based upon data from the state’s grid operator, which does not include “behind-the-meter” PV systems, estimated at around 2.62 GW by GTM Research. If the output of these systems were counted, the portion of demand met with PV and CSP would be even higher.

Over the first five months of 2014, utility-scale PV and CSP met 4.7% of California’s electricity demand, part of the 22% of demand met with renewables overall.

Concentrated Solar Power (CSP) with storage needed

The analysis includes a special focus on CSP, which Chabot argues is more suited to meet demand in California than PV. While CSP output during April and May were higher and more stable than in the first quarter of 2014, CSP remained more variable on a day-to-day basis than PV.

Chabot says that this is due to CSP’s sensitivity to low daily solar irradiation, as the plants deployed in the state lack thermal energy storage. “One conclusion from this result is that future solar thermal power plants should be built only with storage capabilities in order to present at least the same electricity system integration performance than PV plants,” notes Chabot.

Chabot’s full analysis can be downloaded here.