Grid-scale batteries in CAISO earned $2.55/kW-month in June 2026.

That is down 4.6% from May's $2.67/kW and $0.52/kW below June 2025's $3.07/kW, a 16.9% year-over-year decline.

Revenues continue to hold around $2.5-2.7/kW for the third consecutive month.

Average daily highs reached 82.3°F against 83.0°F a year earlier, and average lows held at 55.4°F versus 55.3°F. With temperatures flat, the compression came from the supply side.

Wind generation rose by 31.5% year-over-year as the New Mexico-based SunZia continues to dampen prices.

Greenhouse Gas (GHG) price adders have begun printing non-zero prices for the first time since their launch in 2013. The result is an increase in prices during out-of-solar hours, allowing batteries to benefit from higher peak discharge prices.

The shift in greenhouse gas adders is a consequence of market enhancements introduced in May 2026 alongside CAISO’s Extended Day-Ahead Market (EDAM).

Within the Ancillary Services, Regulation Down prices fell from $5.36/MWh to $3.07/MWh, a 42.7% drop.

Read last month’s report here.

CAISO TB4 price spreads compressed 14% year-over-year

Daily average Top-Bottom four-hour (TB4) price spreads fell from $135/MW to $116/MW year-over-year.

The strongest day of June 2026 was June 21 at $159/MW. The weakest day, June 24, posted just $64/MW.

Evening Day-Ahead prices averaged $35/MWh at the 7pm peak hour, down 32.9% from $52/MWh in June 2025.

Midday charging prices fell to $7.04/MWh at the 2pm trough, from $16.55/MWh a year earlier.

Both ends of the spread moved lower, while the discharge side carried most of the compression.

CAISO’s Greenhouse Gas (GHG) price adders on imports added an average of $2.9/MWh to peak discharge prices - or 11% of the $2.55/kW-month total the fleet earned in June.

GHG price adders are now separated from the Energy component of LMPs, following changes introduced in May 2026 alongside the Day-Ahead Market Enhancements (DAME).

Before the shift, the cap-and-trade surcharge appeared as a negative adder to offers from generators in non-GHG-regulated areas.

Now, generators in the WECC can add the GHG component as a positive component on their bids to meet load in Washington and California.

Peak CAISO load held flat at 31.6GW

Average demand rose 0.8% year-over-year to 25.2GW from 25.0GW. Peak demand only rose by 1.0%, to 31.6GW from 31.3GW. The daily minimum held at 20.6GW.

This is the result of temperatures staying in line with last year's .

Average daily highs (82.3°F) and lows (55.4°F) sat within a degree of last June.

Net load tells the sharper story. The daily minimum deepened to -3.2GW from -1.4GW, while the daily maximum eased to 26.0GW from 26.8GW. The steepest evening ramp of the month hit 11,543MW at 7 pm on June 21, up 13.8% on last June's peak ramp.

Effective load (net load plus BESS charging) held at 3.5GW, level with June 2025. Charging demand grew in step with the deepening net-load trough.

Given that peak load rose only 1.0%, the disappearance of high-price hours came from the supply side absorbing the evening rather than from weaker demand.

SunZia raises wind generation 31.5%, while curtailment mitigates mid-day solar growth

CAISO's battery exports rose from 36.33 to 48.51 GWh per day, a 33.5% increase. The added discharge volume coincided with the 32.9% drop in evening peak prices.

Falling peak prices are closely associated with wind generation rising 31.5% (79.9 to 105.0GWh per day) on account of SunZia’s 3.5 GW addition to CAISO’s energy stack, as reported in previous months.

SunZia increases wind generation overnight more than at midday because CAISO holds only 2,131 MW of transmission rights against roughly 3,167 MW allocated to it, and most of its power flows into the state when Solar is not in surplus.

The project showcases what the future holds in store for CAISO. With the Humboldt and Mora Bay offshore wind projects expected to go live in the early 2030s, battery operators can expect dampened peak prices during windier periods of the year.

On the charging side, solar generation rose 4.7% year-over-year (220.7 to 231.0GWh per day), and peak instantaneous solar output reached 23.0GW, up from 21.5GW. Battery charging volumes rose 33.3% (41.89 to 55.86GWh per day). Negative-price hours tripled from 19 to 66.

Despite the continued deployment of solar projects in California, generation has not increased by much.

This is a consequence of rising curtailment, which reached an all-time high average of 4.8 GW over the past three months.

Midday prices surge by $20/MWh in the South, closing the NP15-SP15 premium

NP15 fell from $124/MW to $112/MW, SP15 from $160/MW to $132/MW, and ZP26 from $171/MW to $132/MW.

ZP26 saw the steepest compression, with all three hubs decreasing from last year.

The SP15-NP15 premium narrowed from $36/MW to $20/MW.