Should you spring clean your solar panels?

Ever since we assembled a 1.6 MW solar panel installation at our headquarters in Mountain View in 2007, we’ve been wondering, “Does cleaning the solar panels make them more effective?” We thought it might, but we needed to be sure. So we analyzed the mountains of data that we collect about the energy that these panels produce — after rain, after cleaning and at different times of the year.

We have two different sets of solar panels on our campus — completely flat ones installed on carports, and rooftop ones that are tilted.

Since the carport solar…