Timeline: What Happens When
- March 26–31: PRA offer window (now closed). Generators and demand response providers submitted capacity offers.
- April 28: MISO posts auction results — clearing prices by zone and total cleared capacity.
- April 29: MISO hosts public Results Review Meeting to discuss outcomes.
- June 1: New capacity obligations take effect for the 2026/27 planning year.
The Capacity Gap: 1.9 GW and Potentially Growing
MISO’s pre-auction data paints a tight picture. With 135.6 GW of accredited capacity against a 137.5 GW requirement, the system enters this auction with a 1.9 GW structural deficit. But several factors could make the effective gap wider:
- DR verification crackdown: For the first time, MISO mandated actual performance verification tests for demand response resources — not hypothetical mock drills. Resources that failed real-world testing were disqualified from offering into the auction, reducing the available capacity pool.
- Coal retirements: Coal-fired generation in the MISO footprint hit a 3-year low in January 2026. Several units that participated in last year’s auction may not have offered this year due to planned or economic retirements.
- Data center load growth: MISO’s load forecast for 2026/27 reflects rising demand from data center interconnections, particularly in MISO South and West subregions.
The RBDC Framework: Why Small Gaps Become Big Price Moves
The Reliability-Based Demand Curve (RBDC), introduced in MISO’s most recent auction cycle, fundamentally changes how capacity prices respond to supply-demand balance. Unlike the old vertical demand curve that produced binary outcomes (surplus = near-zero prices, deficit = price cap), the RBDC creates a sloped curve where:
- Prices rise gradually as the capacity surplus narrows
- Prices accelerate sharply as the system approaches or crosses the reserve margin requirement
- A 1.9 GW gap on a 137.5 GW system (1.4% deficit) can produce clearing prices 3–5x higher than a balanced market
| Scenario | Gap | Est. Clearing Price | YoY Change |
|---|---|---|---|
| Optimistic (gap closes) | 0 GW | $25–40/MW-day | Flat |
| Base case (1.9 GW gap) | 1.9 GW | $60–90/MW-day | +80–150% |
| Pessimistic (DR + retirements) | 3–5 GW | $120–180/MW-day | +300%+ |
Estimates based on RBDC slope analysis and prior MISO auction precedent. Actual results may vary.
Zonal Impacts: Which States Are Most Exposed
- Illinois (Zone 4): ComEd territory faces dual exposure from MISO capacity costs and PJM spillover. The June 1, 2026 start of PJM’s record capacity obligations in northern Illinois compounds the impact.
- Indiana & Michigan (Zones 6–7): Coal retirement concentration makes these zones particularly vulnerable to local capacity deficits that could trigger zonal price separation.
- MISO South (Zones 8–9): Data center load growth in Mississippi and Louisiana is outpacing generation additions. Watch for MISO South to clear at a premium to the system.
Commercial Buyer Action Items
- Review capacity pass-through language: Before April 28, confirm whether your supply contract includes a capacity cost adjustment mechanism. If it does, model the impact of a 2–4x clearing price increase on your annual bill.
- Evaluate demand response participation: If MISO DR clearing prices rise, the revenue opportunity for curtailable commercial loads increases proportionally. Contact your aggregator about 2026/27 enrollment.
- Lock rates pre-results: Some REPs will offer fixed-rate extensions before auction results are public. This is your last window to lock capacity costs at pre-auction levels.
- Watch the April 29 review meeting: MISO’s public Results Review Meeting will provide the first official commentary on zonal price separation, DR qualification rates, and supply adequacy outlook for 2027.
Source: MISO Resource Adequacy Publications; MISO PRA Timeline; MISO MTEP25; FERC Docket ER26-series; Constellation Energy Market Analysis.