The Little Things That Can Make or Break Solar

This week the U.S. solar company SunPower announced an acquisition that a first glance might not seem like a big deal—it bought a company that makes automated solar panel washing systems.

But as the solar industry matures, technology like this could make the difference between solar developments making money and failing. That’s especially the case as developers try to enter markets where solar will compete with other sources of power without massive subsidies or mandates to prop it up.

If you look at a map of the amount of sunlight that reaches the ground around the globe, a few places stand out as prime areas for solar power: the Sahara, the mountains of Chile, the southwest United States, much of India, the Australian outback, Saudi Arabia. But the amount of solar power that any given location can produce can vary markedly depending on factors other than how sunny they are. High temperatures cause solar efficiency to drop. Humidity can be a problem too. And then there’s dust.

Consider the Middle East. “Really big dust storms come through four or five times a year and shut down production,” says Gwen Bender, a product manager for energy assessment at 3Tier, a company that provides mapping data that solar developers can use to estimate how much profit they can make from a solar farm. Some storms can shut down production for a week or more. “That’s not captured by the standard assessment process,” she says. What’s needed isn’t just an understanding of how much dust can accumulate on solar panels, but also what kind of dust it is, because that makes a difference in how much light it will block.

Not only are the sunniest places often dusty, they also don’t have much water around to clean off solar panels. How much solar can Saudi Arabia really afford to keep clean?

SunPower’s acquisition can help. The company, called Greenbotics says it uses just half a cup of water per solar panel, or 90 percent less than washing them by hand. Other innovations could help, too, such as coatings that repel dust. What’s more, some types of solar cells respond better to heat—that’s something First Solar is counting on to help it sell its thin film solar panels.