Extreme-heat grid performance is separating solar-and-storage regions from capacity-constrained markets as data center load accelerates

PJM Interconnection’s early-July heat wave and Texas’ mid-July heat wave were the same category of problem, record air-conditioning load. The operational outcome was nothing alike. PJM saw prices spike above $2,000 per megawatt-hour around its July 2 peak, while the Electric Reliability Council of Texas (ERCOT) hit a July 22 demand record without emergency actions and with real-time prices around $29/MWh, according to E&E News.

For data center operators and the utilities that serve them, that spread is the story. The AI infrastructure boom is arriving in a climate regime that is already producing more frequent, sharper summer peaks. The practical question is no longer whether grids can “handle” large loads in the abstract, it’s which markets can deliver predictable capacity and predictable pricing during the same late-day hours when both people and servers are pulling hard.

Heat peaks are turning into a siting and contracting variable, not a weather anecdote

E&E News, reporting by Benjamin Storrow, described three U.S. regions where extreme heat pushed demand to historical highs: PJM (mid-Atlantic), Southwest Power Pool (Great Plains), and ERCOT (Texas). It also noted a key wrinkle for large-load planners: PJM and Texas sit at the center of the country’s data center buildout, and data centers are a small but growing portion of load in SPP.

GridStatus.io analyst Abby Lestina told E&E News that large loads are coming online and that heat is making the impact easier to see. That framing matters for enterprise operators because it ties two planning timelines together: multi-year interconnection and construction schedules for new campuses, and the immediate reality that heat-driven peaks can show up any summer.

PJM said that demand would have broken a 20-year-old record if not for conservation programs that reduced load, according to E&E News. For operators writing requirements for colocation expansions or self-built campuses, that’s a signal that “availability” increasingly includes curtailment pathways: contractual demand response, utility-managed conservation programs, or on-site load shedding that can be triggered on short notice.

ERCOT’s solar and battery fleet showed what “peak help” looks like at 6 p.m.

The clean-energy narrative around heat events often collapses into a simplistic debate about whether solar can perform after dark. E&E News reported that a U.S. Department of Energy social media post argued that solar did not deliver power after dark during PJM’s peak, prompting pushback from clean-energy advocates and coverage elsewhere.

But the more useful operational comparison in E&E News’ reporting is intra-day timing and controllability. When ERCOT demand peaked around 6 p.m. on July 22, solar was generating roughly a third of the grid’s power, according to E&E News. The story also credited Texas’ large solar and battery buildout as the key difference versus PJM and SPP, which it described as having less solar and storage.

For buyers, “solar share at peak” is an actionable metric because it points to what should be validated in a feasibility study: the local net-load curve, the late-afternoon ramp rate, and the amount of storage that can be dispatched through the top 10 system peaks. If the peak is shifting later in the evening as heat lingers, solar alone changes energy economics but may not change capacity risk unless storage is in the stack.

The global transition milestone is real, but grids are still local

A National Wildlife Federation Facebook post pointed to a separate, upbeat milestone: globally, solar and wind have together produced more electricity than coal for the first time. Even as the post did not provide the underlying dataset, the claim reflects a widely discussed direction of travel in the energy transition.

What the U.S. heat-week experience adds, per E&E News, is that the enterprise consequence shows up at the interconnection and tariff level. A global generation milestone doesn’t tell a hyperscaler whether a specific utility territory can firm up 100 MW of new load without forcing years of network upgrades, or whether a market will expose that load to scarcity pricing during the hottest 20 hours of the year.

E&E News also reported that Dominion Energy executives told investors that nine of the utility’s top 10 power-consumption days have occurred this year, with eight of its highest summer peaks occurring in just over two months. Virginia hosts the world’s largest concentration of data centers, and Dominion’s territory is a bellwether for what happens when the largest load cluster in the country meets sharper weather extremes.

Southwest Power Pool’s experience points to a broader footprint issue. E&E News cited preliminary U.S. Energy Information Administration data showing SPP demand reached nearly 58 gigawatts on July 27, the highest level recorded in EIA’s preliminary power data. SPP also had to implement emergency measures across parts of the Great Plains, E&E News reported. That matters for operators considering “second-tier” markets for cost reasons: lower land and fiber costs don’t automatically translate into lower power-system risk.

What large-load developers and procurement teams should pressure-test this quarter

• Model scarcity exposure explicitly: ask your retail provider or market advisor to replay your expected hourly load shape against 2026 heat-week pricing in the target ISO/RTO. Use E&E News’ reported PJM peak prices (more than $2,000/MWh) as a stress-case benchmark, even if you plan hedges.
• Treat demand response as an engineering requirement, not a program: if the local grid operator relied on conservation to avoid a record (as PJM reported, per E&E News), confirm what dispatch signals, telemetry, and contractual penalties would apply to your facility under emergency or conservation calls.
• Validate “solar at peak” and the storage pipeline in the interconnection queue: ERCOT’s reported outcome during a 6 p.m. peak suggests that solar plus batteries can materially change peak-hour economics. In other regions, confirm the committed in-service dates for storage, not just interconnection requests, before you assume similar performance.
• Ask utilities for a peak-day service plan: Dominion Energy’s statement that nine of its top 10 days happened this year (per E&E News) is a cue to request utility-specific peak-day operating procedures, including voltage management, rotating outage thresholds, and any new large-load tariff provisions under consideration.