Dust and grime on solar panels reduce how much electricity they produce, and large solar farms have far too many panels to clean often by hand. Robots that move along rows of panels clean them automatically, many using little or no water, which matters in the dry, sunny places solar farms favour.
Keeping panels clean recovers lost output and protects the investment, with regular automated cleaning more practical than occasional manual efforts. The robots must suit the panel layout and withstand harsh outdoor conditions, so they are tailored to each site, but on big installations they quietly keep generation near its potential.