CAISO sets new solar peak, steepest three-hour average ramp records

The California Independent System Operator set a new solar peak generation record of 16.056 GW, surpassing the previous record by just 12 MW, but the grid operator will face a challenge Oct. 14 when an eclipse snuffs out solar-powered generation.

The new solar record was set at 11:32am PT Sept. 26, according to CAISO's latest Key Statistics report. The previous record was reached on Sept. 6.

In addition, a new record was set for steepest three-hour average ramp of 20.935 GW at 2:30 pm PT Sept. 24, surpassing the previous record from Feb. 15 by 3%, according to the Key Statistics report.

Solar capture prices averaged $21.62/MWh Sept. 26, down 33% from the September average, according to data from Platts, a division of S&P Global Commodity Insights. September solar capture prices were 51% lower month on month and 70% lower than a year ago.

Solar curtailments averaged 45.23 MW for Sept. 26, 49% lower than the September average, according to solar curtailment index data from Platts. The September solar curtailment index was 72% higher than August, but 99% lower than a year ago.

CAISO installed solar capacity has increased nearly 11% year on year to 17.277 GW, according to the Key Statistics report. Solar accounts for over 60% of total renewable generation capacity.

Renewables account for roughly 70% of CAISO's supply during its midday peak with solar making up over 80% of total renewable generation at its daily peak, according to CAISO data.

Solar eclipse

CAISO will face a challenge Oct. 14 when an annular solar eclipse is expected to snuff out 9.374 GW, while at the same time gross load will increase by 2.374 GW.

The annular solar eclipse begins in Oregon at 9:13 am PT and ends in Texas at 12:03 pm CT, according to NASA. An annular solar eclipse occurs when the moon passes in front of the sun, appearing slightly smaller than the sun, so it does not block the entire solar disk.

The California Balancing Authority Area will be affected from about 8:05-10:57 am PT, ranging from 89% sun obscuration in Northern California to 68% along the Southern California coast, according to a CAISO technical bulletin. CAISO will work with both interstate and intrastate gas suppliers to ensure availability during the eclipse, as well as with hydro and battery resources to assist with large ramps.

"Operators will issue market notifications and operating instructions to require renewable and battery resources follow Dispatch Operating Target to help with grid reliability, and operators can use a Minimum State-of-Charge tool to ensure that storage resources are charged in the real-time market to be able to deliver on their day-ahead schedules," CAISO spokesperson Anne Gonzales said. Oct. 10.

CAISO's battery storage fleet has been growing significantly in recent years. CAISO has 5.888 GW of installed battery storage capacity, a jump of 35% from a year ago and over 200% higher than two years ago, according to the Key Statistics report.

California leads the US in solar capacity with 17.934 GW by the end of Q2, according to the American Clean Power Association's Q2 report. CAISO manages the flow of electricity for about 80% of California and a small part of Nevada.