The Key to Cheap Renewable Energy? Robots

Think Roombas, but for photovoltaic arrays.


With the price of photovoltaic panels at all-time lows, what’s a solar power plant operator to do to cuts costs and squeeze more electricity out of a multi billion-dollar investment?

One word: Robots.

Yesterday, SunPower, the Silicon Valley solar giant, announced that it has acquired Greenbotics, a California company that makes a solar-panel-cleaning robot called CleanFleet. Solar panels tend to get dirty. Dust and grime that builds up on a solar panel blocks sunlight, which interferes with electricity production. A big photovoltaic farm built in a remote sun-rich desert can have hundreds of thousands of solar panels sprawling over thousands of acres. For instance, the 250-megawatt California Valley Solar Ranch project SunPower built on 12,000 acres has 749,088 panels. Cleaning them two to three times a year is a labor-and-water intensive job.

“It’s a massive undertaking,” SunPower chief executive Tom Werner told The Atlantic. “We had to build an $8 million water facility on site so we then could have humans go around with power brushes to clean the panels. It’s slow process and time is money.”

A Roomba for solar power plants, the CleanFleet bots are deployed at night and glide along rows of photovoltaic panels on tank-like treads, cleaning as they go. SunPower says the robot uses less than half a cup of water for each panel, cutting consumption by 90 percent compared with traditional ways of cleaning panels, such as with power washers or spray trucks. Cleaning panels more often can boost a project’s electricity production by 15 percent—more photons means more profits.

The battery-powered robots don’t completely replace humans. A crew of two to three people are still needed to move the robots among the rows of solar panels.

Werner says deploying robots will be crucial in the hottest new solar markets— the deserts of Saudi Arabia and South America—where photovoltaic panels can become completely covered by sand in 100 days, shutting down electricity production. (Saudi Arabia has plans to invest $100 billion to obtain a third of its electricity from solar.)

Expect to see robots do more than clean in the years ahead: Werner says future versions of the robot might be deployed to help assemble solar power plants in the field. That’s already happening in Germany, where a robot called Momo—it looks like a tank with a robotic arm—installs solar panels on racks at solar power plant sites. And Silicon Valley startup QBotix has invented a tuna-shaped robot that races around a solar power plant on a monorail, stopping at each photovoltaic array to adjust the panels’ angle to maximize energy production.  The robots replace expensive mechanical tracking systems prone to breaking down.

“These other systems are the dominant costs of solar now, not the panels,” notes Werner. “Robots can do interesting things to get the labor costs out of the system.”