Originally published for customers May 29, 2026.
What’s the issue?
NERC’s 2026 Summer Reliability Assessment shows risks shifting compared to 2025 as data center growth, transmission constraints, and changing load behavior reshape where the grid gets tight.
Why does it matter?
Because the report identifies which regions, conditions, and resource types are driving reliability concerns, it also highlights where additional infrastructure may be most valuable.
What’s our view?
The reliability conversation shifted from broader uncertainty about whether the grid had enough power to a more regionally defined view of constraints, what conditions drive them, and which resources matter most when they do.
NERC’s 2025 Summer Reliability Assessment read like a grid under broad stress. The report identified MISO, New England, SaskPower, SPP, ERCOT, and WECC-Mexico as elevated risk areas under stressed summer scenarios.
In 2026, New England and SaskPower remained elevated concern areas, while WECC-Northwest moved into the discussion because of hydro conditions, declining snowpack, and growing demand. Meanwhile, MISO and SPP moved out of the primary elevated-risk framing, and ERCOT’s concerns became more localized around electric transmission constraints in Far West Texas. But the reasons those regions improved were not identical.
ERCOT improved partly because of large additions of solar and battery storage, but also because projected net demand declined after tempered forecasts around additions from data centers, other large loads, and how it could respond to demand. NERC noted that ERCOT’s probability of emergency conditions during the highest-risk evening hours fell materially from 2024 levels as battery storage nearly doubled.
MISO improved largely because available resources increased faster than projected demand growth. But the report still notes that reliability risks remain closely tied to wind and solar performance during high-demand periods, particularly later in the summer as solar output fades earlier in the evening.
SPP moved out of the elevated-risk discussion, but the underlying issue did not disappear. NERC still identified low wind output during high-demand periods as a continuing operational concern.
New England largely did not improve. The region remains dependent on imported power with relatively little room for error during stressed summer conditions.
PJM stands apart from much of the discussion. Despite continued concern around data center growth and large industrial load, NERC still classified PJM as relatively low risk because of its sizable dispatchable fleet and reserve levels. Unlike several other regions, PJM’s highest-risk periods still mostly align with peak demand itself rather than the more complicated evening reliability issues emerging elsewhere.
The result is a reliability map that looks less like a broad national warning and more like a series of regional stress points shaped by different combinations of infrastructure, weather, load growth, and resource mix.
NERC reported more than 58 GW of new resources added ahead of Summer 2026, including roughly 30.5 GW of solar, 16 GW of batteries, and 6.7 GW of new natural gas generation. Those additions materially improved reliability conditions in several regions.
Below, we show where new generators have come online and where generators have been retired since last June, the start of the summer period, as reported in NERC’s reliability assessments. We can see that generator additions cluster around the Midwest, New England/the Mid-Atlantic Coast, California, and Texas. These areas include regions where reliability was at risk last summer. Generation growth focused on these areas contributed to the improvements in reliability reported this summer.
In ERCOT and parts of the West, battery additions helped manage evening reliability risks after solar output declines. In PJM, a large dispatchable generation fleet continues to provide operating flexibility during peak demand periods. In New England, imported power and fuel availability remain critical reliability considerations. In MISO and SPP, renewable output variability continues to shape risk during stressed conditions.
Below, we break down capacity additions/retirements by region and energy source, focusing specifically on regions where reliability risk has changed. As previously stated, ERCOT has substantially increased its battery resources and continued to add to its solar fleet. In MISO and MRO SPP, the other two regions where reliability risk decreased, significant capacity additions have also been made, mostly to solar and wind, which are resources these regions have direct access to. Notably, reliability risk has increased in WECC Northwest, even as generation has grown. As previously stated, NERC attributes this to changing hydro conditions, declining snowpack, and growing demand.
The common thread is not that one resource type is winning everywhere. It is that reliability problems are increasingly regional, and the infrastructure solving them is becoming more regional as well. Some regions may increasingly rely on fast-ramping natural gas generation. Others may need storage, electric transmission expansion, or some combination of all three. Geography, available resources, market structure, and political willingness to build infrastructure still shape reliability outcomes region by region.
Reliability debates are often national. Reliability failures rarely are.
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