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How Free Is Solar Energy?

How free, really, is solar energy?

2 min read
map showing average daily solar radiation
Illustration: Bryan Christie Design; Source: National Renewable Energy Laboratory (NREL)

Renewable-energy technologies promise to liberate us from fossil fuels. But this implies that their energy payback periods—the time it takes for a system to recover the energy used to produce it—is just as important as financial payback. If you install solar cells on your roof, you want the system to pay for itself eventually, but you also want to help your country get a grip on global warming and stop depending on foreign fossil supplies.

“Most people who take the initiative to put photovoltaics on their homes and businesses are looking at the economics, certainly, but they’re looking beyond that, too,” in the words of Gary Schmitz, a spokesman for the National Renewable Energy Laboratory, in Golden, Colo.

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This photograph shows a car with the words “We Drive Solar” on the door, connected to a charging station. A windmill can be seen in the background.

The Dutch city of Utrecht is embracing vehicle-to-grid technology, an example of which is shown here—an EV connected to a bidirectional charger. The historic Rijn en Zon windmill provides a fitting background for this scene.

We Drive Solar

Hundreds of charging stations for electric vehicles dot Utrecht’s urban landscape in the Netherlands like little electric mushrooms. Unlike those you may have grown accustomed to seeing, many of these stations don’t just charge electric cars—they can also send power from vehicle batteries to the local utility grid for use by homes and businesses.

Debates over the feasibility and value of such vehicle-to-grid technology go back decades. Those arguments are not yet settled. But big automakers like Volkswagen, Nissan, and Hyundai have moved to produce the kinds of cars that can use such bidirectional chargers—alongside similar vehicle-to-home technology, whereby your car can power your house, say, during a blackout, as promoted by Ford with its new F-150 Lightning. Given the rapid uptake of electric vehicles, many people are thinking hard about how to make the best use of all that rolling battery power.

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