The energy loss due to dirty solar panels can be as high as 25%! It all depends on your location. It is very important to maximize the light getting into your solar panels and in turn, increase your financial reward.
Pollution, traffic dust, leaves and even bird droppings contribute to preventing sunlight from reaching the solar cells in solar panels. Solar panels should be inspected at least every six months depending on your local climate.
Some dry climates almost require hardly any cleaning. But even in desert areas dust and pollen can accumulate. There are not enough rain showers to naturally rinse the solar panels. Even in the pacific northwest there is a dry season, where between July 1 and October 1 there is only 1 inch of rain.
There is also pollution to contend with. You can be next to or downwind from a highway, factory/industrial zone or an agricultural field may yield enough dirt to justify cleaning.
Rainwater is not enough to keep solar panels clean. Imagine a car windshield that is not cleaned for 5 months. You would lose a lot of visibility. The dirt and grime would accumulate and ‘green’ over the glass. Rain also contains dirt in itself that attaches to the surface after the rain dries. Notice the part of the windshield that the wipers do not reach. That film of dirt is what a whole solar panel can look like with no cleaning maintance!
You can clean the solar panels yourself much like you would wash your car. Some warm water and a mild cleaner like dish washing soap will do to remove the accumulation of dirt and grime.
Or you can have a solar cleaning panel cleaning service. Some commercial cleaning services can do this added service. The same equipment used in power washing and window cleaning is used to clean the solar panels.
Commercial cleaning crews will have the ladders and safety equipment to do the job right. It can be a hassle if you don’t have the right gear.
So how often should you clean your solar panels? These 5 factors can help you determine just that:
1) Your location
Does it rain regularly, do you have a dry season?
2) Are your solar panels tilted?
Tilted panels require less cleaning as dirt just slides down.
3) The amount of dust in your area
4) Your electric rate
5) The cost to clean your panels
If you do it too often you will be wasting money