This spring has provided fertile ground CAISO batteries to operate, starting with the rollout of the ISO’s Extended Day-Ahead Market (EDAM) where its first added participant was PacifiCorp. Along with the EDAM, CAISO rolled out its Day-Ahead Market Enhancement (DAME) upgrade that was designed to provide more market price discovery in the integrated market regulation up and down markets and which was is a benefit to all flexible resources given the transparency it provides for all ancillary service and flexible capacity payments intertwined within the marketplace. Against this backdrop, batteries have also been operating in an environment characterized by significant solar growth in southern California and the Desert Southwest prompting midday curtailments and negative pricing, which is a benefit to battery arbitrage operations. In our latest Battery Report, “What’s Next in CAISO?”, we detail the key takeaways from CAISO’s battery fleet in May as well as the landscape moving forward as thing within California and the West are set to start heating up.

Figure 1 | Monthly Comparison of Value Streams ($/kW-M)

The table above is part of the CAISO Monthly Battery Dashboard, where it breaks down the Energy-Balanced Regulation (EBR) and RTM and DAM Arbitrage opportunities ($/kW-M) for each gen hub (NP15 and SP15). A couple of items are worth pointing out for the month of May with the first being that NP15’s EBR averaged $8.01 while SP15 pulled up at $4.98. The former has not seen such a value since last year around this time as the market trended lower throughout Q3/Q4 2025 and January 2026. Yes, the monthly average is lower than May 2025, but the trend line is pointed in a different direction (upward). The latter has the same upward trajectory, just at a lower scale given all the binding constraints that are intermixed within the CAISO DA and RT markets. The second item is the RTM and DAM arbitrage values taking on slightly stronger tone within SP15 while NP15 was basically unchanged from the previous month. Both are lower in comparison to the March 2026 values while the DAM posted numbers present a flat valuation across the board.

Figure 2 | CAISO Peak Load – Actual and Forecast

Temperatures are currently climbing in CAISO and are expected to break 100 degrees this afternoon in Sacramento, Bakersfield, and Fresno and lead to an increase in system load up to 37.7 GW for the evening peak. Lingering warmth persists in the forecast through the middle of next week, followed by a return to milder conditions. Increased load within CAISO is good news for its solar fleet but can negatively impact batteries with reduced oversupply nudging midday LMPs higher during a key charging window. Already we’ve seen a reduction from the prodigious rate of renewable curtailments in CAISO. After averaging 46.7 MWh per day during May, through the first nine days of June wind+solar curtailments are averaging just 23.8 MWh, although this is still a massive increase over the 8.7 MWh average from June of last year.

Figure 3 | CAISO Running Total Annual Renewable Curtailments – System and Local (MWh)

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