Solar panels are typically cleaned when they begin generating less electricity than before, or when the efficiency of your solar panels drops below 90%. In order for them to function properly, it's important that your solar panels are kept clean.

Clean solar panels can be a lot more efficient than dirty ones because dust and other particles will absorb energy from the sun instead of letting it pass through. This leads to less power being generated. It also means that some of the energy coming in from the sun will be lost due to reflection off of dust particles on your panels.

So when do you know if it's time to clean your solar panels? You can tell if it's time by looking at their efficiency rating (the percentage of sunlight converted into electricity). If this figure drops below 90%, then you should consider having them professionally cleaned by a company like Sol R Clean. They are experienced professionals in the field and they know how exactly how much work is involved in cleaning these things properly so they won't damage them while doing so.