Thankfully most solar panels these days come with waterproof features. Most panels in the market can withstand ordinary outdoor rainfall. Some come with water splash protection. But, if it rains heavily, there are chances of damage. If the entire panel including the LED lights in the panel comes with an IP65 rating for waterproofing, it can resist not only rain but also damaging dirt particles in the air. When it rains mildly, it will be good for the panels as well if the panels you have shortlisted are waterproof. The reason is that the rainwater will wash away dirt if any in the panel. If it rains, it is better to ensure that you place the panels in such a way that water won’t stand in the panel. It means that when you place them in a slanting position, water will run away. Even, if it rains, solar panels can continue to generate power from the sun. Of course, as compared to summer, the power production might reduce in the winter. But, still, the panels will continue to generate energy.