Total California solar output hit a new record this week, placing sun-driven generation at the top of the overall California generation mix so far this month.
California solar photovoltaic generation hit a new record Thursday at about 100.2 GWh/d, according to Cal-ISO data, breaking the previous solar PV record of 100.1 GWh/d set May 7.
Solar PV and solar thermal combined were about 105.5 GWh/d Thursday, also the highest total for solar output in the ISO's footprint.
If solar remains strong for the rest of May, it could become the top generation source in the overall fuel mix for the state, right behind imported power.
In the past, thermal generation -- comprising mainly natural gas-fired generation -- typically topped the overall fuel mix.
In some spring months, hydro generation can sit atop the overall generation mix as winter precipitation comes off the mountains.
California imports so far this month have averaged just under 27% of the overall ISO fuel mix, which is slightly below the May 2017 level of 28%.
Solar generation this May has averaged above 16% of the ISO fuel mix, putting it slightly above thermal generation, which is averaging just below 16%. Last May, thermal generation was around 18.5%.
Hydro generation has been depressed this spring because of below-average winter precipitation.
Hydro has averaged about 14% of the fuel mix this month, which is about six percentage points below last May, when California's water supply saw above-normal levels.
Also picking up from last year is nuclear generation, at around 9% of fuel mix so far this month, which is more than double May 2017 as a refueling outage occurred at Pacific Gas and Electric's Diablo Canyon nuclear power station.
Wind generation rose about three percentage points to just shy of 12% of the fuel mix.
The California Energy Commission estimated there was roughly 16.2 GW of solar PV capacity near the end of 2017.
The growth of solar is expected to continue in the coming years.
According to the ISO generation queue, about 1.2 GW of solar PV is expected to connect to the grid in the rest of 2018, 2.3 GW in 2019 and 6.6 GW in 2020.
Further, in 2020, recently enacted CEC rules kick into play that will mandate solar energy systems on every new home built in California.
