They have a robot that cleans the panels. It's a big, flat surface so they don't really need anything much more advanced than a Roomba. Apparently they also h

They have a robot that cleans the panels. It's a big, flat surface so they don't really need anything much more advanced than a Roomba. Apparently they also have special shoes that maintenance people can wear that distribute the weight properly so they can walk on them if they have to.