Clean your panels every once in a while

If your panels are installed on the ground, cleaning them two-three times a year is a must. A while ago Google engineers conducted an experiment on a solar farm in California: they left some panels to collect dust for 15 month and then came and washed them. The production doubled instantly. If your panels are placed on a tilted roof, you can let the rain take care of them, but not forever: eventually the dust on top of panels is going to turn to mud. The exact frequency of cleaning solar panels depends on the area you live in. To perform the cleaning you can call a special service or do it yourself. It's a lot like washing windows, just don't use soap: it leaves residue which reflects sunlight and collects dust and debris.