Executive Summary
The purpose of this report is to provide market participants a monthly summary of day-ahead and real-time markets performance for May, 2026. The key market performance highlights are presented here:
CAISO area performance:
Peak loads for ISO area increased a little in May compared to the previous month.
The cumulative frequency of prices in FMM above $250/MWh decreased from 0.10 percent in April 2026 to 0.06 percent in May 2026, while the cumulative frequency of negative prices increased from 30.61 percent in April 2026 to 31.33 percent in May 2026. Average FMM DLAP prices increased for PGAE, SCE, and VEA, while SDGE experienced a decrease relative to the previous month.
The cumulative frequency of prices in RTD above $250/MWh increased from 0.10 percent in April 2026 to 0.11 percent in May 2026, while the cumulative frequency of negative prices increased from 31.31 percent in April 2026 to 32.11 percent in May 2026. Average RTD DLAP prices across PGAE, SCE, SDGE, and VEA increased relative to the previous month.
The cumulative total congestion rent for interties increased from $2.06 million in April 2026 to $2.39 million in May 2026. Majority of the congestion rents in May accrued on NOB_ITC(37.3%) and IPPUTAH_ITC(36.6%). Congestion rents on the MALIN500_ISL decreased from $1,497,049 in April 2026 to $596,181 in May 2026. Congestion rent of NOB_ITC increased from $378,732 in April 2026 to $891,270 in May 2026.
Net Monthly Balancing Surplus in May was $30,299,479. The auction revenues credited to the balancing account for May were $5,321,830. As a result, the balancing account had a surplus of approximately $35.621 million compared to $12.740 million in the previous month, which was allocated to measured demand.
In May, the monthly IFM average procurement decreased for regulation up, regulation down, and non-spinning reserves, while increasing for spinning reserves compared to the previous month. The monthly IFM average prices increased for all ancillary service products compared to the previous month, except for spinning reserves, which decreased.
The total bid cost recovery increased from $12.43 million in March 2026 to $12.90 million in April 2026. Out of the total monthly bid cost recovery payment for the three markets in April, the IFM market contributed 12.7 percent, RUC contributed 52.9 percent, and RTM contributed 34.4 percent of the total bid cost recovery payment. (need to update)
RTIEO increased from $3.72 million in March 2026 to $5.87 million in April 2026. RTCO increased from $22.40 million in March 2026 to $24.66 million in April 2026. (need to update)
The monthly exceptional dispatch uplift payments decreased from $6,549,624 in March 2026 to $4,317,762 in April 2026. (need to update)
The number of market disruptions decreased from 63 in April 2026 to 44 in May 2026. On May 1, there were 15 (8 FMM, 2 HASP, 5 RTD) disruptions.
The total volume of exceptional dispatch increased from 85,761 MWh in April 2026 to 99,720 MWh in May 2026.
The curtailment of renewable energy decreased in May 2026 compared to the previous month. Most curtailments continued to be solar.
Flexible ramping up uncertainty payment increased from $34,712 in April 2026 to $86,380 in May 2026. Flexible ramping down uncertainty payment increased from $24,321 in April 2026 to $85,211 in May 2026.
Western Energy Imbalance Market (WEIM) performance:
Total WEIM RTIEO increased from $0.30 million in April 2026 to $15.34 million in May 2026. Total WEIM RTCO increased from -$5.63 million in April 2026 to $1.85 million in May 2026.
The cumulative frequency of FMM ELAP prices above $250/MWh increases from 0.03 percent in April 2026 to 0.06 percent in May 2026. The cumulative frequency of negative FMM ELAP prices decreased from 25.94 percent in April 2026 to 21.53 percent in May 2026. The cumulative frequency of RTD ELAP prices above $250/MWh increased from 0.05 percent in April 2026 to 0.10 percent in May 2026. The cumulative frequency of RTD ELAP negative prices decreased from 27.98 percent in April 2026 to 24.44 percent in May 2026.
Total WEIM BCR increased from $0.40 million in April 2026 to $2.79 million in May 2026.
Total flexible ramping up uncertainty payment increased from $0.23 million in April 2026 to $0.40 million in May 2026.
Total flexible ramping down uncertainty payment increased from $38,647 in April 2026 to $212,931 in May 2026.
Total forecast payment decreased from $16,243 in April 2026 to -$1,014,567 in May 2026.
| Month | WEIM | FMM ELAP Prices | RTD ELAP Prices | Price Difference |
|---|---|---|---|---|
| 2026-05 | AVA | $12.85 | $12.81 | $0.04 |
| 2026-05 | AVRN | $12.16 | $11.28 | $0.88 |
| 2026-05 | AZPS | $8.14 | $8.92 | -$0.78 |
| 2026-05 | BANC | $16.70 | $16.71 | -$0.01 |
| 2026-05 | BCHA | $2.41 | $1.40 | $1.01 |
| 2026-05 | BHBA | $13.04 | $17.23 | -$4.19 |
| 2026-05 | BPAT | $12.46 | $11.56 | $0.89 |
| 2026-05 | EPE | $16.85 | $18.93 | -$2.08 |
| 2026-05 | GWA | $11.20 | $11.43 | -$0.23 |
| 2026-05 | IPCO | $12.67 | $12.50 | $0.17 |
| 2026-05 | LADWP | $5.10 | $7.14 | -$2.04 |
| 2026-05 | NEVP | $9.89 | $10.72 | -$0.83 |
| 2026-05 | NWMT | $12.51 | $13.82 | -$1.31 |
| 2026-05 | PACE | $13.02 | $17.09 | -$4.06 |
| 2026-05 | PACW | $12.08 | $11.58 | $0.50 |
| 2026-05 | PGE | $13.84 | $12.81 | $1.03 |
| 2026-05 | PNM | $8.67 | $9.50 | -$0.83 |
| 2026-05 | PSEI | $12.22 | $11.21 | $1.01 |
| 2026-05 | SCL | $16.24 | $14.22 | $2.02 |
| 2026-05 | SRP | $9.55 | $10.32 | -$0.77 |
| 2026-05 | TEPC | $10.08 | $13.51 | -$3.42 |
| 2026-05 | TIDC | $17.06 | $17.03 | $0.03 |
| 2026-05 | TPWR | $13.67 | $12.42 | $1.25 |
| 2026-05 | WALC | $8.03 | $9.46 | -$1.43 |