A new automated washer for ground-mounted solar panels will be available to California dairymen via service contract soon.

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Editor & Podcast Host / Progressive Dairy

The new product, MegaWash, was developed by Coldwell Solar and was recently named one of World Ag Expo’s top new products.

The mini-tank-like vehicle is just 6 feet wide and can fit in between the rows of most commercial solar panel installations. Its side-mounted hydraulic cleaning arm with microfiber brushes looks like something out of an automated car wash.

In fact, the washing it provides is similar to a commercial car wash, says Don Carlson, Coldwell Solar’s vice president of project development.

“It does a phenomenal job,” Carlson says. “When you see the cleaned panels after this passes, you’d think they look as clean as taking your car through a car wash.”


A single operator can clean a 1-megawatt solar installation with the new washer in about four hours. The system uses filtered and deionized water. About 800 gallons are needed for one wash. Other methods of cleaning and rinsing solar panels can take up to 4,000 gallons, the company claims.

The reduced water usage, the company says, is especially important for California producers who have seen water-use restrictions during the past several years.

The automated washer’s use of deionized water is what produces the “spot-free” finish that many associate with automated car washes, Carlson says.

“If you wash your car with just a hose, you know that your car is still dirty. This system gives you a thorough washing but uses very little water to do it,” Carlson says.

Carlson says the biggest misconception about solar panels is that they never need cleaned. However, according to an analysis of Caldwell Solar systems’ production data, the company claims dirty solar panels can reduce power production as much as 20 percent annually.

That lost power production could cost as much as $49,000 to $70,000 over the course of a year.

“We monitor a panel’s production for our customers. We can tell when a system isn’t producing at the level it’s supposed to be. One factor we couldn’t control before was how often customers were washing their panels, but now we have a solution for that,” Carlson says.

The process by which panels become dirty is known as “soiling” in the solar power industry. A variety of factors can influence how quickly panels get dirty, including wind direction and frequency; proximity to animals, fieldwork or operating machinery; and soil type.

Carlson says most solar panel owners who have cleaned their systems by hand or even just rinsed them off with a water truck will likely ask, “Isn’t there a better way?” after their first cleaning.

Coldwell Solar will provide cleanings to any commercial or agricultural ground-mounted solar panel owner, not just its own clients, on an annual service contract. The cost of the service will be determined based on the frequency of need, number of panels to be cleaned and on-site water availability.

For Coldwell Solar customers, the cleanings can be provided on-demand, as the company will monitor power generation to determine when soiling is affecting production.

“For example, a cotton gin’s panels may need to be cleaned more frequently than a citrus grower’s,” Carlson says.

Although cleanings may be needed throughout the year and vary in frequency for each operation, the summertime often demands owners clean their panels more frequently, Carlson says.

This is because summer is an active time period for harvesting and crop production, which generates more air particulates than other times of the year. There aren’t as many rainstorms in the summer to clear the air of those particulates. Plus, summer is also the most effectual time for power production, so any system inefficiencies, such as soiling, will be magnified.

Coldwell Solar says it will deploy only trained solar panel technicians to operate its new automated washer. This is an added value of its new washing service, says Rita Edwards, director of marketing for the company.

“The technician is able to do more than just clean the panels, but also do a visual check of the system generally and make sure everything is accurate,” Edwards says.

After the company developed the automated washer this past summer and pilot-tested the washing service for a few months this fall, Edwards says the company held an internal competition to help determine the name for the new washing equipment and service.

Company employees submitted more than 50 different names. Eventually, MegaWash was chosen for its relevance to the industry and its descriptive nature.

“In the solar industry, we have terms like kilowatt and kilowatt-hour or megawatt and megawatt-hour. The size of the systems that this unit will be cleaning are usually accounted for in megawatts,” Edwards says. “It’s a natural fit to name it MegaWash.”

Edwards says solar panel owners can sign up for the new washing service immediately.  PD

PHOTO: This automated solar panel washer will soon be used to fulfill service contracts to clean commercial ground-mounted solar systems in California. Coldwell Solar developed the new equipment and service, which were named a top new product by World Ag Expo.  Photo courtesy of Coldwell Solar.