CAISO sets solar peak generation record of 15.178 GW, the fourth record this year

The California Independent System Operator set a new solar peak generation record for the third month in a row, as solar output has reached the highest level on record so far this month.

The new record of 15.178 GW was reached at 12:11 pm PT June 2, surpassing the previous record from May 23 by 72 MW, according to the latest CAISO Key Statistics report published June 12.

The records come as no surprise since CAISO solar capacity continues to rise, even if the increase is slower than expected, Morris Greenberg, a senior manager with the low-carbon electricity team at S&P Global, said June 13.

"There are about 3.5 GW under construction and due on by the end of 2024," Greenberg said. "Solar/storage projects will account for the bulk of CAISO additions for the foreseeable future."

So far in June, solar generation output has averaged 141.964 GWh, the highest monthly average on record, according to CAISO data.

Following the trend from past years, the June 2 record marks the fourth solar peak generation record set in CAISO so far this year. The first record was reached April 27 at 14.774 GW, followed by a record of 14.812 GW May 12, according to CAISO reports. CAISO solar set four peak generation records in 2022 between March 24 and June 7, and in 2021 set four such records between March 1 and May 27.

Solar pulls prices

The surge of solar generation pulled down solar capture prices. CAISO SP15 solar capture prices sank 86% year on year to $9.38/MWh June 2, according to Platts data.

S&P Global's renewable generation curtailment index showed CAISO on-peak local solar curtailments were 384.58 MW June 2, an 130% year-on-year jump, while system curtailments were 69.6 MW, a drop of 58.4% year on year, according to data from Platts, a division of S&P Global Commodity Insights. There are two types of generation curtailments: systemwide curtailments occur when there is an oversupply and localized curtailments occur when the amount of power from one transmission point to another is controlled for congestion management.

As the solar record was reached June 2, SP15 on-peak day-ahead locational marginal prices dropped to $17.56/MWh, a nearly $13 discount to the off-peak package, according to CAISO data.

Day-ahead and real-time on-peak power prices in CAISO proved significantly lower year on year during the May and June trading days when solar generation reached record highs. NP15 and SP15 day-ahead on-peak LMPs were both valued near $17.50/MWh June 2, tumbling 78.3% and 77.3% year on year, respectively, according to CAISO data. Likewise, on-peak real-time LMPs at the two hubs were in the low $20s/MWh, down 69.2% and 66.5% from a year ago.

California solar capacity

CAISO has added more than 2 GW of solar generation capacity in the last year and 7 GW in the past five years, including behind the meter, Greenberg said. CAISO managed about 80% of California's electric flow.

California has the most utility-scale solar capacity in the US with 17.754 GW by the end of the first quarter, 42% more than the second-ranked state, Texas, which has 12.538 GW, according to the American Clean Power Association's quarterly report.

California also ranks first for battery storage capacity with 5.034 GW, more than double the second-ranked state, which was also Texas, which has 2.165 GW, according to ACP's report.