While NERC did track about 7 gigawatts of new fossil gas generation added since last summer, that was eclipsed by the 30.5 gigawatts of solar generation capacity added in the same period, according to the report.
Solar doesn’t provide its full nameplate generation capacity during morning and evening hours or when it’s cloudy, and of course it generates nothing at night. But it does generate a lot of power during the hottest hours of typical summer days. NERC found that the 30.5 gigawatts of new solar are contributing 16.4 gigawatts of capacity at times of peak summer demand.
Batteries that can store excess solar power for use later in the day have also come online at a rapid clip. NERC tallied more than 16 gigawatts of battery capacity added since last summer.
Most of those batteries have been built in Texas and California, as well as in other parts of the U.S. West, the report notes. Solar-charged batteries have been saving the California and Texas grids from summer shortfalls in recent years, helping to dramatically reduce the risk of heatwave-driven blackouts.
But solar and batteries have also bolstered other regions.
“MISO’s capacity resources have improved since Summer 2025,” the report says, with the new additions “made up of predominantly solar resource installations, along with smaller amounts of natural gas, wind, and battery storage resources.”
“This is not a conversation about renewables being tied to reliability risk,” she said. “This report reflects the conclusion that renewables are significant contributors to reducing risk on the system today.”
To prove the point, Eidbo highlighted the section of NERC’s report that calculates what proportion of the total capacity of solar, wind, hydropower, and battery storage is available to serve the peak demand hour in a given area. That’s an important metric to determine how helpful different resources are during crunch time for the grid.
NERC found that the 20.4 gigawatts of solar available in MISO are capable of providing 60% of their nameplate generation capacity during peak hours. NERC’s assessment of the peak load contribution of MISO’s fleet of roughly 3.6 gigawatts of battery storage was even higher, at 97%.
NERC found similar, if slightly lower, values for solar and batteries to meet summer peak hours in the Southwest Power Pool, a grid operator serving 14 Midwest and Great Plains states. The report assigned a 54% peak contribution rating to SPP’s 3.9 gigawatts of solar, and an 84% peak contribution rating to the region’s 1.3 gigawatts of battery storage.
Both of those regions have fallen from “elevated” risk to “normal” risk from summer 2025 to summer 2026, Eidbo noted — and both “have very high percentages of nameplate capacity from energy storage systems.”
This is a good sign that solar and batteries, both of which can be built more quickly and cheaply than gas plants, can also serve the grid when the summer heat hits and demand goes through the roof.
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