Department of Market Monitoring 2025 Special Report on Battery Storage posted

The California ISO (ISO) Department of Market Monitoring (DMM) has posted the 2025 Special Report on Battery Storage to the Special reports and presentations webpage, providing analysis of battery resource participation and performance in the ISO market footprint during 2025. Key findings of this analysis include the following:

• Battery storage capacity in the ISO market footprint reached 25,700 MW at year-end 2025, a 42 percent increase from year-end 2024. This growth was most concentrated in California and the Desert Southwest Region.
• Batteries account for a significant portion of energy supply and capacity during the late afternoon and early evening when net loads are highest.
• Batteries account for a significant portion of load during peak solar hours.
• Net market revenue for batteries in the CAISO balancing area decreased from an average of about $53/kW-yr in 2024 to $45/kW-yr in 2025.
• Batteries received $6.3 million of real-time bid cost recovery payments in 2025, representing 5 percent of total bid cost recovery to generators.
• DMM continues to find that the fleet of primarily 4-hour batteries used to meet resource adequacy requirements are partially unavailable to the market during consecutive hours with tight system conditions.

For questions, please contact Matt Gevercer at mgevercer@caiso.com, and the Department of Market Monitoring at DMM@caiso.com.