California's grid survived a record-setting September heatwave due to several factors, including increased capacity, improved communication between agencies, and significant conservation by commercial and residential customers.

That's new analysis provided by the California Independent System Operator (CAISO), which outlined positives, and areas for improvement, stemming from the heatwave that struck much of the West from Aug. 31 through Sept. 9.

Part of the grid's gritty survival was credited to the increased capacity added under California's resource adequacy program since 2020, including 3,500 MW of battery storage.

Imported electricity from neighboring balancing authorities and market enhancements made since August 2020 also played key roles in maintaining reliability, CAISO said.

Maybe no source played a more critical role, though, than individual Californians.

CAISO issued Flex Alerts calling for voluntary consumer conservation for a record 10 consecutive days. On Sept. 6, when record temperatures were set all over California and the West, demand on the ISO system reached a record peak of 52,061 MW.

The all-new GridTECH Connect Forum will examine California's 2022 heatwave and what's next for demand response programs in the state. Register to attend the inaugural GridTECH Connect Forum event in San Diego on Feb. 6, 2023. The GridTECH Connect Forum is bringing together DER developers, utilities, and regulators together around the critical issues of DER interconnection integration.

Regional cooperation also contributed to maintaining reliability. That same evening, about 6,500 MW of net energy imports from neighboring energy providers and balancing authorities were made available to the grid when it was most strained. Another 1,000 MW of energy was transferred to the grid via the WEIM, a real-time market with participants throughout the western United States. 

It wasn't all good news. The report identified several areas for improvement in system operations.

First, the grid could benefit from improved coordination between day-ahead and real-time operation of batteries to ensure they are optimally dispatched and used most effectively during short and long heat events.

Second, a software issue associated with how the market allows or curtails low-priority exports under very high demand conditions should be addressed (A software upgrade was deployed in mid-October to address this issue).

And last, CAISO recommended that changes be made to the calculations used in the WEIM resource sufficiency test that resulted in the ISO’s balancing area only failing the test during two 15-minute intervals during the heat wave, when the ISO should have actually failed during six 15-minute intervals.