As in real estate, the primary answer is location, location, location. Depending on several factors, such as buildup of pollutants, such as smokestacks, exhaust systems, jet aircraft exhaust, animal farms, wind, rain, dusty agricultural areas, areas adjacent to salt water, freeway exhaust, or dust, the amount of loss varies with every location. Properties adjacent to cement plants, gravel plants, landscaping nurseries etc. are examples where your location is more likely to be affected by dirt and debris. Other factors such as mounting angle also contribute greatly to power loss. The flatter the mounting angle the greater the loss.
Many articles written by solar panel manufacturers or persons they hire to conduct studies, want to minimize the idea of power loss from dirt and debris. Think of it this way, if you sold solar panels, would you really want to highlight the fact that they lose power when they get dirty? Can you imagine leaving a car outside for 20 to 25 years; how clean do you think the windows would be? A solar panel is a simply a window with the “magic” happening below 3mm. of glass. If the glass is dirty or covered with debris, the sunlight does not penetrate as well.
Some articles I have read try to convince the reader that losses only run about 5-7%. That maybe in certain areas, but as a whole power loss in central California, the California desert areas, Arizona desert areas and areas along the southern U.S. where solar panels concentrate due to more sunlight per year, experience much greater loss; particularly if they are not cleaned.
We spoke with a major Southern California Power Company who had test panels at a site in Pomona. These panels were mounted dead flat. They had extensive monitoring equipment. They reported that at this site, they lost 38% of the electrical output in six months. What was really shocking was that they reported that half of the loss occurred in the first 30 days!
Also note here that if you mount a framed panel dead flat, the aluminum frame is about 1/8” above the height of the glass. This acts as a bowl to keep water on the glass surface. So, when it does rain, any dirt and debris that may have been reduced by rain is simply rearranged on the surface. This can cause additional problems, such as “hot spotting” which may damage or kill a panel. Reverse Polarity can also occur.
While some of the pictures are indeed extreme examples showing loss approaching 50% on the first picture, can you really afford to throw away electricity? When you elected to purchase a solar power system you based your decision on how much it would cost to buy a watt of electricity. If you are not getting the output you paid to get, you really paid more per watt than you thought.
Heliotex www.heliotex.com can provide you with residential or commercial automatic cleaning system for pennies per watt. We can help you recover the electricity that you paid dollars per watt to buy. Contact us at info@heliotex.com or call us at 760-837-0390 for any additional questions you may have.
Gene Hunt
Heliotex
760-837-0390