While there is no right and wrong answer to this question, it is generally recommended that your solar panels are cleaned around once per year.
It might seem often given that solar panels require little maintenance, but cleaning PV panels is a relatively simple process and shouldn’t take too long to carry out.
In Ireland, you may need to clean your panels in winter after heavy bouts of snow. Clearing the snow away can be done simply with lukewarm water.
While your solar panels should be cleaned once a year or so, depending on where you live and the environment in which your house is situated, more frequent cleaning could be necessary to ensure your solar panels can absorb the most sunlight possible.