Solar panels may work in the rain or snow, but the efficiency will be much lower, depending on the thickness of the cloud. Rain is not bad, nor is it an element that has a negative impact on solar panels. Much of what has been said about a cloudy day also applies to a rainy day. The big difference is that rain is very beneficial for energy production because it washes and cleans the dust from the solar panels, thus improving their efficiency when the sun shines again.