Every night, nearly a hundred robots come to life in the arid desert of southern Israel and get busy cleaning rows and rows of solar panels.
The robots are designed by startup Ecoppia as an alternative to the conventional, but also labor-intensive, method of sending human workers to hose and wipe down panels manually or use a truck-mounted sprayer to do so.
Dirty panels produce less electricity, but the need to use water for cleaning those panels, especially in dry regions, makes even a clean power project less eco-friendly. And in certain remote corners, water extracted from the ground is too brackish for use without being treated, which adds to the production cost of a solar power plant.
In dusty areas such as the Middle East and India, solar panels could lose electricity production by 10 percent to 35 percent over time if they remain unwashed, Eran Meller, CEO of Ecoppia, told me in a recent interview.
Ecoppia’s robots dry clean each panel and move from the top to the bottom of a row of panels. The Israeli startup found a loyal customer in Arava Power, with which Ecoppia installed the first set of its robots on a solar farms (5 MW total) earlier this year in the Negev desert. Ecoppia is installing more robots in other Arava projects.
“It doesn’t pay to manually clean thousands of panels in hundreds of acres of arid desert fields,” said Jon Cohen, Arava’s CEO. “Now we have a process that costs less, and above that we are upping the output.” Using the robots so far has led to about 2-3 percent more electricity production than employing humans, Cohen said.
The challenge of keeping solar panels dust free will grow as more solar power projects are built worldwide. In many cases, cheap labor and ample water supply will continue to make manual washing the low-cost choice for solar power plant owners.
But for companies with projects in different climates — and the need to show they run a low-carbon, sustainable operation to secure permits or dodge lawsuits from environmental groups — a less energy intensive cleaning process could be desirable.
SunPower, which builds solar power projects around the world, bought Greenbotics a year ago after trying out the California startup’s technology in a solar farm it built in the state’s Central Valley. The big selling point of Greenbotics is that its technology uses up to 90 percent less water than manual cleaning.
Ecoppia was founded in January 2013 but started its development work a few quarters before that. The company has raised an undisclosed amount from the Swarth Group, GlenRock and Gandyr.
Each robot, which weighs about 86 kilograms (190 pounds), is essentially two large microfiber brushes on eight wheels, with the brushes rotating at a high speed to generate airflow as they move down the panel.
The airflow removes a bulk of the dust while the brushes get rid of the rest. The robot runs on two 12-volt lead-acid batteries at night. Solar electricity recharges the batteries during the day. After the robot completes its task, it returns to a docking station and uses the rotational energy to get rid of the dust captured by the microfiber.
Ecoppia has designed its robotic system to perform optimally in a row of solar panels that runs 300 meters by 6 meters (984 feet by 20 feet), Meller said. Each robot can take care of hundreds of panels each night, depending on the size and configuration of the installation. Power plant operators can control the robots remotely and receive data about the machines’ performance and maintenance needs.
Ecoppia makes money by selling and installing the robots and providing maintenance and data analytics. The cost to hire Ecoppia to engineer and install its robots runs from $0.03 to $0.06 per watt, Meller said.
With about one year of field data of its robots’ performance, the startup projects that its equipment and services could save 840 million liters of water for a 300 MW solar park over 20 years while increasing electricity sales by $180 million, Meller said. Of course, those projected savings and revenues will vary widely in different countries or even within a country, depending on the local operational costs and how much the utilities are willing to pay for power. Arava, for example, is cleaning its solar panels nightly in Israel while in California, SunPower is cleaning its panels several times a year.
Currently, Ecoppia’s robots are cleaning about 500,000 panels per month. It will be installing robots for other Arava projects, including 40 megawatts that have yet to be completed, that will bring the monthly total to 10 million by the end of 2015, Meller said. The robotics developers are working on entering the U.S. market next year.
Arava has been working closely with Ecoppia in engineering the robots to fit its projects’ configurations. Arava also secured written assurances from the manufactures of the panels it uses — Suntech Power, JA Solar and Trina Solar — that outfitting the robotic systems on their panels won’t change their warranties.
Ecoppia is working on engineering its robots to work on solar panels that are held up by trackers, which tilt the solar panels to follow the sun’s movement, said Cohen, who is looking at using trackers for future projects.
The close relationship with Ecoppia makes Arava a potential buyer of the robotic startup down the road. But Cohen would only allow that the his company is “closely affiliated with Ecoppia. We will be involved in Ecoppia going forward.”