During the fall and spring, cloudless afternoons produce a spike in solar power at a time when milder temperatures necessitate less air-conditioning. When that happens, the state’s solar farms make more energy than the state can use, and some panels are simply turned off. This maddening problem—a result of what energy wonks call the “duck curve”—has been getting worse as the amount of available solar power outpaces the state’s ability to move that power around. In early 2017, just more than 3 percent of the state’s solar was wasted this way. The total reached 6 percent by 2022, according to California’s grid operator, and 15 percent in the early afternoons of March 2021. Wind power also can be wasted if the weather is especially breezy, and California’s combined curtailment of wind and solar set a new record this April.

Now the state has punted this dilemma to its residents. In December, the California Public Utilities Commission voted to slash the amount of money homeowners with new solar panels can make from “net metering,” the practice of selling your own extra solar back to the power company. Because the math for buying new panels is less favorable, fewer Californians are installing them, according to the Los Angeles Times. Many sunny rooftops that could generate clean energy simply won’t.

California is outpacing the rest of the country in the energy transition, but its misadventures in solar are going national. Moving away from fossil fuels requires a huge expansion of renewable energy in America. One government report estimated that meeting Joe Biden’s goal of supplying half of the country’s energy with solar would mean doubling America’s capacity annually until 2025—and then quadrupling it annually through 2030. But without better ways to transport that solar power or store it for later, California and several other states are already turning off perfectly good solar panels and clawing back incentives that entice Americans to install their own. Far more of America’s sunny potential is about to go to waste.

A little clean-energy wastage is inevitable, Carey King, the assistant director of the University of Texas at Austin’s Energy Institute, told me. Such is the very imperfect nature of integrating unpredictable renewables onto a power grid built for the predictability of fossil fuels. Compared with an inflexible coal or gas plant, solar panels are easier to turn off and on, so they are first to be cut during times of energy surplus. Ideally, we could stash away sun power and use it to light up the skyline at night, but that would require a build-out of big batteries that is still in early stages. Excess solar can be moved to less sun-soaked places to help them burn fewer fossil fuels, but electricity doesn’t just teleport from sunny Palm Springs to drizzly Portland. Moving it across long distances requires heavy-duty power lines and navigating the bureaucracies of various agencies that operate them.

Take Texas: The state’s famously independent power grid has relatively few interconnections with neighboring systems to send spare renewable energy elsewhere. When Texas started making a big push toward renewables in the 2000s, King said, the state began turning off solar panels and wind turbines, and slowing the construction of new ones because it lacked enough so-called transmission lines capable of zipping renewable energy from windy West Texas to the big cities in the east. A state-mandated power-line expansion solved the problem then. Now, as Texas’s total wind-energy capacity leapt from 10 gigawatts in 2010 to 40 gigawatts by 2022, those new wires have reached their limit. In 2022, Texas wasted 5 percent of the wind and 9 percent of the solar energy it could have created. Without another big fix to the grid, those numbers could jump to 13 percent of wind and 19 percent of solar by 2035.

Across the country, clean energy is similarly hemmed in by the limits of transmission lines. Existing plants can’t get all their electricity where it needs to go, because there aren’t enough power lines for them to thrive, says Timothy Hade, the co-founder of Scale Microgrid Solutions, which builds clean-energy systems for homes and businesses. The Biden administration has pledged billions to modernize the grid and expand high-voltage transmission lines, but actually building them is very, very, very hard. As Robinson Meyer wrote in The Atlantic last year, “If you want to build new transmission, then you need to win the approval of every state, county, city, and in some cases, landowner along the proposed route.”

The Herculean task of building new transmission lines wasn’t such a pressing issue before the rise of renewable energy. But now solar power is so pervasive that parts of the country have no choice but to turn down the supply. Although that could take the form of fewer industrial-size wind and solar plants coming to fruition, the other option is giving a cold shoulder to people who have their own solar panels and sell it back to the power company through net metering. After all, net metering can create lots of power: California gets more than 15 percent of its energy from big solar farms and roughly 10 percent from residential rooftop panels, according to the EIA.

Like California, other states are choosing the second option. Indiana phased out net metering, and in North Carolina, solar advocates are now suing the state for allowing its giant utility, Duke Energy, to force a minimum monthly bill upon its customers and adjust net metering in a way the advocates say will reduce payouts. Arizona is considering cutting payments for homemade solar, as is Madison Gas and Electric in Wisconsin, according to Energy News Network. A few other close calls show the perilous state of net metering: This year, it has so far survived in New Hampshire, barely, when utilities backed the practice at the last moment. Last year, Florida Governor Ron DeSantis vetoed a bill that would have ended the practice and hit home-solar users with extra fees.

That isn’t to say that the clampdown has happened everywhere. Texas, for example, has allowed Tesla to set up a “virtual power plant” so that people with Elon Musk’s solar panels and batteries can make gobs of money selling back energy whenever they have extra. And there are legitimate fears about using this method as a way to grow the country’s solar supply. Hade calls net metering a “blunt instrument”—too crude an approach for the complex energy system of the future. One major problem is that solar-panel owners tend to be far richer than the average American but don’t pay their fair share for the upkeep of the electrical grid, which is built into the price the power company charges everybody else. The more houses that have rooftop solar, the argument goes, the more that people without solar must pay to maintain all the infrastructure that everyone needs. “Net metering can’t be the end-all solution as we go forward,” King said. “It’s just going to create a little bit too much disparity.”

The growing backlash against net metering isn’t just a response to wasted solar power—it’s also about for-profit power companies wary of rooftop solar panels that don’t make them money. The idea of turning homes, apartment buildings, and businesses with solar panels into mini power plants is a potentially transformative one—and net metering is a big part of how people can afford solar panels in the first place. Solar panels can cost upwards of $10,000, and in California, the extra cash from net metering has helped residents recoup the expensive cost of panels in five to six years. Now it will take up to 15 years, according to one analysis. 

In that way, America will end up squandering more potential clean energy down the line. Fewer than 10 percent of U.S. homes have installed solar panels so far. The rest constitutes an enormous swath of untapped real estate—billions of square meters of sun-drenched rectangles that could be making clean energy. Incentives for solar energy still exist from states and the federal government, but the result of slowing down net metering is that residents will put on smaller solar panels that make only enough energy for their own use, Hade told me, because they can’t make much money selling their bonus juice. Or they won’t get solar at all.

The squeeze on homemade solar is a missed opportunity in the making. A retreat from net metering makes solar-panel owners less like mini power plants and more like doomsday preppers, perhaps filling the backup battery in the basement with electricity to get through a blackout but adding nothing to the country’s clean-energy supply. With a more nuanced form of net metering to allow people to sell their surplus, or with the advent of “microgrids” that tie together communities and allow them to share energy, American rooftops could contribute gigawatts toward running the country on clean energy. Such a DIY approach would be a way around our inability to build new power lines, but it is deeply at odds with the way America has operated for a century, and will seemingly operate for many more years to come: The power company sends you the power, and you use it.