The California Independent System Operator (ISO) projects electricity supply for summer 2021 to be better than last year. Although a series of policy changes and redesigns of ISO’s system has occurred, along with improved communications and coordination protocols, the power grid is still prone to be overstressed during extreme heat waves—according to the ISO’s summer outlook released this month.

The 2021 Summer Loads and Resources Assessment estimates the energy grid will be more prepared than it was last year, having additional capacity to help avert rotating power outages such as those in August 2020. The extra capacity came from resource procurement ordered by the state. Still, if this summer brings heatwaves similar to those last year, the state could risk supply shortages and possible emergency conditions.

“The ISO and its partners in the state and throughout the western region are focused on being as prepared as we can for the summer heat,” said Elliot Mainzer, president and CEO of the ISO. “New resources are coming online by summer, and we have taken the lessons learned from last year to make modifications to our market and operations.”

“This makes us cautiously optimistic that there will be enough electricity to meet demand this summer. But, there are remaining risks to reliability, such as an extremely prolonged heatwave affecting wide swaths of the West, or serious wildfires,” he continued.

The ISO’s annual Summer Assessment evaluates the expected supply and demand in order to prepare for the hot weather months of June through September. Imports will be critical in this summer’s power grid reliability and sustainability. Conservation will be vital to padding the grid to reduce stress during emergency and high-demand conditions.

Demand for air conditioning is typical during hot summer evenings and when solar production goes offline. ISO plans to issue Flex Alerts—voluntary calls to consumers to lower electricity usage between 4:00 p.m. and 9:00 p.m.— in coordination with the California Public Utilities Commission (CPUC) when system conditions are forecasted to be tighter.

The ISO, and its partners, will continue seeking out and using the best measures during emergencies to avoid rotating outages.