When someone gets a new rooftop solar installation, the second question they always ask is “how often do I need to clean my solar panels.” We’ll answer that question on this week’s show — taking into account the different effects of rain, dust and electric rates (BTW, the first question people always ask is “how do I read my electric bill,” but that’s a topic for another show).
Rooftop solar panels get dirty primarily from wind-blown dust and pollen. Birds are usually not a problem unless your last name is Hitchcock and you live in Bodega Bay. As panels get dirtier, their output declines. A small amount of soiling — say a light dusty film — may only cause a 5 percent output decline. However, when panels get very dirty — perhaps in an agricultural area or location that does not get regular rainfall — the output decline can be greater than 20 percent. A good heavy rainstorm will usually wash away most of the accumulated soiling.
I use the term “usually” because on panels that are tilted at about 5 degrees or less, the rain may leave a puddle of muddy debris along the lower edge of the panel. When this puddle dries, sometimes a thick layer of dirt accumulates along the lower row of cells (sometimes moss and weeds may even grow in these areas). Depending on the design of the system, this small accumulation of dirt can cause a very significant decrease in output.
So the answer to the question: “how often should I clean my solar panels” really depends on five factors:
- Your location (does it rain regularly or only during certain months)
- The tilt angle of your panels (steeply tilted panels tend to stay much cleaner than panels that are close to horizontal)
- The amount of wind-blown dust
- Your electric rate (if your electric rate is high then it is more worthwhile to clean your panels)
- The cost to clean your panels.
For more about cleaning your solar panels, please Listen Up to this week’s edition of the Energy Show on Renewable Energy World.
About the Energy Show
As energy costs consume more and more of our hard-earned dollars, we as consumers really start to pay attention. But we don’t have to resign ourselves to $5/gallon gas prices, $200/month electric bills and $500 heating bills. There are literally hundreds of products, tricks and techniques that we can use to dramatically reduce these costs — very affordably.
The Energy Show on Renewable Energy World is a weekly 20-minute podcast that provides tips and advice to reduce your home and business energy consumption. Every week we’ll cover topics that will help cut your energy bill, explain new products and technologies in plain English, and cut through the hype so that you can make smart and cost-effective energy choices.
About Your Host
Barry Cinnamon is a long-time advocate of renewable energy and is a widely recognized solar power expert. In 2001 he founded Akeena Solar — which grew to become the largest national residential solar installer by the middle of the last decade with over 10,000 rooftop customers coast to coast. He partnered with Westinghouse to create Westinghouse Solar in 2010, and sold the company in 2012.
His pioneering work on reducing costs of rooftop solar power systems include Andalay, the first solar panel with integrated racking, grounding and wiring; the first UL listed AC solar panel; and the first fully “plug and play” AC solar panel. His current efforts are focused on reducing the soft costs for solar power systems, which cause system prices in the U.S. to be double those of Germany.
Although Barry may be known for his outspoken work in the solar industry, he has hands-on experience with a wide range of energy saving technologies. He’s been doing residential energy audits since the punch card days, developed one of the first ground-source heat pumps in the early ‘80s, and always abides by the Laws of Thermodynamics.
This podcast was originally produced by Spice Solar and was presented here with permission.
Lead image credit: Patrick Breitenbach | Flickr