NYISO Releases Summer 2026 Capacity Assessment

CHPE's Entry Splits Summer 2026 Into Two Capacity Periods

This week, the NYISO presented its Summer 2026 Capacity Assessment. The headline numbers warrant attention. Start-of-summer margins are the narrowest in at least a decade, with 417 MW of baseline margin, a deficit of 1,679 MW under 90/10 conditions, and a deficit of 3,370 MW under 99/1 conditions. Zone J carries negative margins across every scenario, including with SCRs.

The assumptions underlying the assessment were undermined by CHPE's May entry into the energy market and its election to begin capacity participation in July.

The assessment was constructed on the basis of CHPE-Out parameters for the start of summer, with Danskammer, Gowanus, and Narrows units carried in the resource mix. CHPE entered the energy market on May 13 following completion of trial operations, and has elected to begin capacity market participation in July. That sequence sits ahead of the timeline indicated in NYISO's April 29 FERC filing and earlier public guidance on the project's commercial trajectory.

As a result, the reliability picture for Summer 2026 now divides into two distinct periods, and the assessment as presented reflects only the first.

June Operates as the Assessment Depicts

CHPE carries no capacity obligation for the month, and the margins shown are a reasonable representation of the conditions operators are preparing for Zone J is the area to watch most closely, with deficits ranging from 23 MW at baseline to 1,005 MW under 99/1 conditions even with SCRs counted. Up to 3,166 MW of emergency operating procedures are available to bridge gaps, though that figure depends on neighboring control areas having capacity to offer and on demand-side and voltage-reduction tools being called. If a June peak materializes, as it did last year, NYISO retains the ability to schedule CHPE energy economically or to seek emergency assistance from Hydro-Québec, but no capacity is backed against those flows. CHPE could offer into a potential supplemental auction up to the amount required to clear any deficiency, though it is not obligated to offer the full 1,250 MW.

July through October Presents a Different Picture

Statewide margins improve by approximately 1,250 MW once CHPE begins supplying capacity. Zone J sees a smaller improvement of roughly 700 MW, as CHPE becomes the largest single contingency in the zone and the transfer capability is restated to reflect that. Either way, the reliability outlook for the second half of summer is meaningfully stronger than the assessment as presented suggests.

The divergence between the assessment and the operating reality has drawn measured pushback. Presenting the assessment without a clear CHPE-in companion case risks conveying a distorted view of summer reliability, particularly for Zone J. NYISO has signaled that the question of a revised or supplemental release will be considered, without a firm timeline.

A related question concerns fleet decisions premised on CHPE remaining out of service. CHPE has been a central input in evaluations of whether units such as Danskammer need to remain in operation. NYISO's planning team has indicated that the assumptions matrix for theQ2 STAR that is underway will not be formally revised, but that substantive changes will be reflected in study findings consistent with prior STAR cycles. We will watch this question develop as the NYISO releases the Q2 STAR.

Implications for Market Participants

Summer 2026 should be approached as two distinct capacity periods, and any positioning built around a later CHPE in-service date should be revisited. June and the July through October window differ across several variables that matter for market participants, including reliability risk, capacity margins, ICAP parameters, and Zone J LCR treatment, and those differences affect monthly and strip exposure in different ways. More broadly, when a resource of CHPE's scale is approaching commercial operation, NYISO operational filings and market data are a more reliable reference point than project-level commentary, which in this case did not align with how the timeline actually played out.

What We’re Watching

The near-term question is whether the NYISO will issue a revised or footnoted Summer 2026 Capacity Assessment ahead of the June board materials. The July ICAP parameter update is another item to follow closely, particularly for how it reflects CHPE availability and the corresponding Zone J LCR adjustments. Beyond that, Luminary will continue to track the implications of CHPE's entry through the NYISO's 2026 Reliability Outlook, the 2026 RNA, the upcoming Potomac Economics State of the Market Report, and the next round of STAR reports. The fleet evaluations premised on CHPE-Out conditions will be the leading indicator for how the reliability and capacity picture evolves through the balance of the year.

Luminary Energy LLC provides advisory services to wholesale power generators and market participants in NYISO and ISO New England. To learn more about Luminary Energy's services or to connect with a member of our team, contact us at contact@luminary.energy.