US ISOs Still Bullish on Renewables

EIA data shows significant growth in ERCOT, CAISO, and MISO.

Recently published EIA generator data revealed significantly higher renewable capacity growth in the first 10 months of 2025 - led by batteries and solar. But the story varies considerably depending on where you look.

ERCOT added 9 GW of renewables so far this year, more than any major US ISO, continuing Texas's push for flexible generation. CAISO matched ERCOT's battery additions at 4 GW, but solar was a different story - only 1 GW installed, down from 2.6 GW in 2024. That's a tempered number for an ISO that's led solar deployment for many years.

MISO showed impressive solar additions in 2025, matching its growth from recent years. And although MISO has signaled interest in adding more batteries to its fleet, the capacity additions indicate that's yet to materialize.

Then there's PJM, which had zero battery capacity additions in 2025. The ISO added around 1.5 GW of solar—the only significant renewable activity in a market that continues prioritizing conventional generation.

Data source: EIA generator capacity additions, January–October 2025