How Automatic Solar Panel Cleaning Systems Work

By: Maria Trimarchi

Unless you like the idea of hoisting yourself onto the roof, an automatic system might be a good investment.
Unless you like the idea of hoisting yourself onto the roof, an automatic system might be a good investment.
AP Photo/Craig Ruttle

Photovoltaic (PV) solar energy is an efficient and renewable energy source -- PV systems use crystalline silicon or thin film (although more materials are being developed) to convert sunlight into electricity without producing air pollution or hazardous wastes. Fossil-fuel-fired power plants, however, produce much more than electricity. In 1999, for example, roughly 2.2 billion tons (1.9 billion metric tons) of carbon dioxide, 12 million tons (10 million metric tons) of sulfur dioxide and 7 million tons (6.3 million metric tons) of nitrogen oxides were the side effects of fossil-fuel-generated electricity [source: Leahy]. How does that compare to PV-produced electricity? Each kilowatt of PV-generated energy offsets 830 pounds (376 kilograms) of nitrogen oxides, 1,500 pounds (680 kilograms) of sulfur dioxide and 217,000 pounds (98,429 kilograms) of carbon dioxide annually [source: U.S. Department of Energy].

PV systems are flexible, filling power needs ranging from the low demand of a cell phone, camera or single home to the high demand of a city or town. Installing a PV system to power your home will run you thousands of dollars (or less depending on the level of power you want) [sources: The Solar Guide]. Solar companies have only recently hit their industry target of $1 per watt (when you use 1,000 watts for 1 hour, that's a kilowatt-hour) [source: Kanter]. By contrast, the average price for fossil fuel-generated electricity in the United States is 11.26 cents per kilowatt-hour for consumers, and the average American home uses 10,656 kilowatt-hours (kWh) per year [sources: LaMonica and Johnson].


Installing a PV system is a big investment, for sure, but one that's worth the price -- both financially and environmentally. But to keep your system in tip-top condition and performing at its peak levels. Solar panels require a good scrub from time to time, kind of like windows.

Importance of Solar Panel Cleaning

Kindrell Hutchinson of the Leveda Brown Environmental Park and Transfer Station does things the old-fashioned way -- a light rinse with a hose.
Kindrell Hutchinson of the Leveda Brown Environmental Park and Transfer Station does things the old-fashioned way -- a light rinse with a hose.
Joe Raedle/Getty Images

Leaves, bird poop and airborne particles (from dirt and pollen) all dirty your solar panel investment. Dirty panels mean power loss -- grime and debris reduce the ability of the solar array to perform at full capacity. A solar array is made up of several solar modules wired together, and each solar module is made up of solar cells all mounted collectively in a frame. Solar cells, in turn, are made of semiconductor materials, such as silicon. One side of a solar cell is positive, the other negative. When sunlight hits a solar cell, it excites the electrons in the semiconductor material, and it's this energy that can be captured as electricity. If the cells aren't clean, then less sunlight is able to be absorbed and less electricity is generated.

The potential energy loss depends on the level of filth your solar panels have accumulated. Energy loss could reach 25 percent, but some reports bring the number as high as 30 percent for consumers who never clean their system [source: Heliotex].


Homeowners with small solar systems may choose elbow grease as their preferred cleaning method. Solar panels, like windows, can be cleaned with warm water and dishwashing soap to remove any dirt or residue. When you wash them, you're washing the glass surface and the frame of the panel.

Sweat equity has its downside, though, and manually cleaning solar panels can come with risks. First, you (or the person who is doing the cleaning) risk personal injury. If you're not comfortable on your roof, consider your personal safety before ascending a ladder. Also, while soap and water won't hurt your solar panels, you still run the risk of damaging them (remember this is an electrical system you're cleaning) or even your roof if you don't know what you're doing. Some things are best left to professionals.

And what about large or industrial-sized solar systems? Should you hire a maintenance crew of panel washers to scale the place, window washer-style? There's always the automatic cleaning system option.

Solar Panel Cleaning Agents

To keep in top shape, solar panels need to be kept clean.
To keep in top shape, solar panels need to be kept clean.
David McNew/Getty Images

Automatic solar panel cleaning systems keep your solar panels clean and your money in your pocket -- remember dirty panels mean less electricity generated.

The Heliotex Automatic Solar Panel Cleaning System is intended for any size photovoltaic system, from small residential to supersized industrial. It's a patent-pending system, fully programmable to wash (with soap and water) or rinse (water only) your panels as frequently as you like. It's recommended that you wash your panels every one to two weeks and rinse every two or three days to help minimize the buildup of dirt and other debris.


Heliotex Automatic Solar Panel Cleaning Systems use low-volume spray nozzles, connected to each panel, an existing water supply such as an outdoor water faucet and a programmable controller (which runs on a 110 volt power supply). The systems use a specially-formulated, biodegradable soap concentrate that is mixed into the water line during wash cycles. A second rinse follows the wash cycle.

Industrial cleaning systems, for 100 kilowatt installations or larger, work similarly to residential systems. The OCS Energy Automatic Solar Panel Cleaning system, called SolarWash, also requires nozzles be attached directly to the array of each solar panel. These nozzles, run by a microprocessor, spray and wash the panels. The system has a programmable logic controller and a Web-based software interface -- a PV system operator can schedule or initiate a panel washing with the touch of a button.

While professional installation is required for the automatic cleaning system, it requires little attention from homeowners and operators once it's in place, other than an occasional soap concentrate refill and water filter replacement.

Lots More Information

Related HowStuffWorks Articles

  • Fehrenbacher, Katie. "Are Dirty Solar Panels a Big Problem?" earth2tech. 2008.
  • Heimbuch, Jaymi. "SolarWash: First Automated Cleaning Solution for Solar Panels." TreeHugger. 2008.
  • "Heliotex Announces First Patent Pending Automatic Solar Panel Cleaning Systems." Reuters. 2009.
  • Johnson, Drew. "Al Gore's Personal Energy Use Is His Own "Inconvenient Truth" - And Replies." The Chattanoogan. 2007.
  • Kanter, James. " First Solar Claims $1-a-Watt 'Industry Milestone'" Green Inc. Feb. 24, 2009.
  • Keshner, M.S. and R. Arya." Study of Potential Cost Reductions Resulting from Super-Large-Scale Manufacturing of PV Modules." National Renewable Energy Laboratory (NREL). 2004.
  • Knier, Gil. "How do Photovoltaics Work?" Science@NASA. NASA. 2002.
  • LaMonica, Martin. "Solar-power prices slide toward 'grid parity'." Green Tech. CNET News. 2009.
  • OCS Energy, Inc.
  • "OCS Energy Introduces SolarWash -- The Automated Solar Panel Cleaning System." Yahoo! Finance. 2008.
  • "Pollution from Fossil Fuel-Fired Electric Power Plants." Office of Senator Patrick Leahy.
  • "Solar Cost FAQ." The Solar Guide.
  • "Solar Energy Technologies Program: Photovoltaics." Energy Efficiency and Renewable Energy. U.S. Department of Energy.
  • "Solar Energy Technologies Program: Why PV is Important to You." Energy Efficiency and Renewable Energy. U.S. Department of Energy.
  • "Solar Panel Cleaning Services." Heliotex Solar Panel Cleaning Residential Home Services. 2009.