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The grid operator charged with keeping the lights on in Philadelphia, Chicago and Washington DC has declared a record number of energy emergencies this year. But for California and Texas, once notorious for massive outages, the tally is zero.

The difference comes down to football field-sized batteries and new solar arrays, which have been greenlit at a breakneck pace in California and Texas but are caught up in a sclerotic approval process in PJM Interconnection LLC’s territory.

Batteries and solar power have become key backup electricity sources in California and Texas, the two most-populous US states, as the data center boomexacerbates strain on grids already pressed by growing industrial demand and extreme weather. The grid covering much of the Midwest also has adopted those sources more robustly than PJM, though not on the scale of the Golden or Lone Star states.

On a combined basis, the Texas and California grids serving more than one-third of US electricity customers expanded batteries and solar arrays to 36% of overall capacity in the 18 months up to June, compared with about 8% in the PJM region. For the Midwest Independent System Operator that serves a swath from the Canadian prairies to the Gulf of Mexico, the figure was 12%.

“The contrast this summer was pretty stark: the grids that added resources quickly had more tools to manage extreme conditions,” said Sean Kelly, chief executive officer of power-demand forecaster Amperon Holdings Inc. “PJM had less room for error.”

An energy emergency occurs when power supplies show signs of running short of demand, according to the North American Electric Reliability Corp. There are three tiers of emergencies, ranging from warnings about low electricity reserves to rolling blackouts.

Infrastructure companies and entrepreneurs that have tried to expand battery and solar output in PJM have been largely frustrated by a system dogged by internecine conflict between politicians, utilities and ratepayers pursuing competing goals. The combination of regulatory uncertainty and historically weak financial incentives also discouraged investment, AES Corp. President Ricardo Falu said in an interview.

The Electric Reliability Council of Texas that oversees roughly 90% of the state’s power demand more than doubled battery-storage capacity to 24.5 gigawatts in just 18 months, according to Potomac Economics, the grid’s independent market monitor. The California Independent System Operator saw storage rise 49% to more than 17 gigawatts during the same period. For comparison, a gigawatt is equivalent to a traditional nuclear reactor.

“This is the kind of buildout speed that attracts data centers,” said Felix Chow, head of US West advisory at Aurora Energy Research. “Access to electricity is now a determining driver for data center development.”

For its part, PJM had roughly 16 gigawatts of solar and batteries as of late June, according to grid watchdog Monitoring Analytics.

That’s for a region that exceeds the combined customer base of Ercot and CAISO. At the same time, there’s more than 68 gigawatts of solar and battery projects still stuck in the PJM application process.

The divergence in battery and solar expansion is part of the reason that Texas is on the verge of overtaking PJM as the data center capital of the US.

It’s also been a factor in power prices. In the so-called day-ahead power market, the average price in PJM’s benchmark Western hub for June through Sept. 18 was up 53% from a year earlier.

In a major Southern California hub, the price was up just 2.8% for that period, while the Dallas area saw prices drop 13%, according to data from Intercontinental Exchange and MCG Energy Solutions.

PJM, which serves more than 67 million customers across 13 states, operated in a state of emergency for four consecutive days during an early July heat wave, grid data shows. Since the start of the year, PJM tapped emergency supplies on a record 16 days.

The grid operator has approved roughly 7 gigawatts of battery and hybrid-generation projects, which may include some solar, that have yet to be built, PJM spokesman Jeffrey Shields wrote in an email. Another 20.6 gigawatts of storage and hybrid projects are eligible to sign grid-connection agreements in the first three months of 2027, he added.

“Storage and solar-storage hybrid resources can certainly help serve net load for the evening peaks, when solar generation is heading to zero while demand is decreasing at a much slower pace,” Shields wrote. “But batteries alone don’t address the problem – we also need all of the resources that have cleared the queue or are in the queue to actually get built.”

When California electricity demand surged on Sept. 9 to just a few gigawatts short of the record set four years ago, prices climbed but nothing like in the past. Spot prices topped $800 a megawatt-hour, according to California ISO, well short of the $1,000-plus figures during a 2022 heat wave.

“I suspect the most substantial difference is that we have added more than 35GW of capacity to the system since 2020 and we have added more than 17GW of battery storage capacity,” Jayme Ackemann, a CAISO spokesperson, wrote in an email. “That additional capacity has made it possible to effectively manage the grid during peak demand conditions, which is contributing to greater pricing stability.”

Similarly, the Texas grid has proven more resilient to weather-driven demand spikes.

“This summer we set records in June, July, August and in September, so we are not experiencing one extraordinary weather event and one peak period,” Ercot Chief Executive Officer Pablo Vegas said during a recent board meeting. “We are operating at demand levels that would have been exceptional just a few years ago.”