With some parts of the country already facing heat waves, the organization in charge of setting reliability standards for the American electric grid is warning that a scorching summer could lead to a shortage of power generation in some regions.

The warning comes as the National Oceanic and Atmospheric Administration says there’s a 99% chance that 2024 will rank among the five warmest years on record and 55% chance it will be the hottest on record.

Overall, though, the analysis by the North American Electric Reliability Corporation painted a rosier picture than last year’s report, in part because of a surge in solar power development.

The nation has enough energy supply to handle normal peak demand, called “load” in the electric industry, largely because of 25 gigawatts of new solar power capacity — at full capacity that’s the rough equivalent maximum output of 25 large fossil or nuclear power plants. (The number of homes that can be powered from one gigawatt of solar can vary widely across the country). But the new panels have helped move some areas from what NERC calls “elevated risk” of power shortfalls in last year’s analysis? to “normal risk” this year.

“Resource additions are providing needed capacity to keep up with rising peak demand in most areas,” Mark Olson, the organization’s manager of reliability assessments, told the Federal Energy Regulatory Commission last week. New power transfer agreements, growth in demand response programs, which incentivize customers to reduce power usage during times of grid stress, and delayed power plant retirements “are also contributing to an overall improved resource outlook for the upcoming summer,” NERC says.

A solar surge

A separate FERC staff presentation said solar will make up 10% of overall national electric generation capacity by the end of this summer, with natural gas providing 42%, coal providing 14% and wind power at 13%.

Solar power is growing fast across the country, with the U.S. hitting five million total solar installations (most of them residential), per the Solar Energy Industries Association. Reaching that milestone took 50 years, but the industry group projects that hitting 10 million solar installations will only take six years. Solar power for the first time accounted for more than half of new electric generation capacity added in 2023, the group noted.

The U.S. Energy Information Administration expects “a record addition” of new utility-scale solar power this year, with about 36.4 gigawatts projected to be installed. More than half of that new capacity is planned for Texas, California and Florida.

The Gemini facility scheduled to begin operation this year near Las Vegas, with a planned solar capacity of nearly 700 megawatts and battery storage capacity of up to 380 megawatts, is expected to become the nation’s largest solar project.

Battery storage is also growing rapidly, with more than 14 gigawatts expected to be added this year, according to the EIA. Batteries complement solar generation well, since solar’s peak production doesn’t generally line up with peak demand on the grid, which happens later in the day. Batteries allow excess solar power to be banked for when it’s needed.

But a changing power mix also comes with new challenges and risks, NERC warned.

In his presentation to FERC, Olson said that while the overall summer electric reliability outlook has improved, some regions are seeing what he described as growing risks during extreme weather.

“Shortages could occur when demand is high and solar, wind or hydro output are low,” he said.

Those regions include parts of the Midwest and South in the grid area managed by the Midcontinent Independent System Operator, New England, Texas, much of the Southwest and California. Grid operators, though, are becoming increasingly adept at planning and running electric grids with large amounts of intermittent resources.

“It’s refreshing to finally get the recognition that renewables can help with reliability,” said Simon Mahan, executive director of the Southern Renewable Energy Association.

Shifting seasons and climate change

While most of the country has historically been “summer-peaking,” meaning regions hit their highest demand for electricity during the summer months, some areas are increasingly seeing demand spike in winter, a trend that is expected to continue as result of heating electrification, other decarbonization policies and more extreme, protracted cold weather events. Indeed, the majority of recent electric grid failures have been during severe winter weather, such as Winter Storm Elliott in 2022, which caused blackouts in several southern states and Uri in 2021, which caused a catastrophic collapse of the Texas electric grid that caused an estimated 246 deaths.

But summer heat still poses risks, NERC says, contributing to both high demand and power plant outages, such as at natural gas power plants.

“Last summer brought record temperatures, extended heat waves and wildfires to large parts of North America,” the organization said. And though energy emergency alerts were few and no electricity supply interruptions happened as a result of insufficient power resources, grid operators “faced significant challenges and drew upon procedures and protocols to obtain all available resources, manage system demand and ensure that energy is delivered over the transmission network to meet the system demand.” Utilities and state and local officials in many areas also “used mechanisms and public appeals to lower customer demand during periods of strained supplies,” NERC added.

Christy Walsh, a senior attorney at the Natural Resources Defense Council’s Sustainable FERC Project, said the reliability reports show how climate change is central to the pressures facing the electric grid.

“And it needs to be at the center of our solutions too,” she said in a statement to States Newsroom. “Earlier and more intense hurricanes brought on by increasing sea temperatures are a new and noteworthy concern, and this underscores the need for more large-scale transmission and connections between regions. Most of the new additions were wind, solar and storage, and last summer especially we saw just how crucial these resources can be during extreme heat events. We need to make sure we have a grid that can withstand the weather and move resources around during times of stress.”