Cleaning your Spaceships campervan is required in order to return it in the same condition as when you picked it up (see for more info).
You can take your campervan through a wash bay, even if your campervan has a solar panel on its roof. Just make sure you go to a touch-less / brush-less wash bay, so there is no risk of damages. Or use a DIY wash bay with manually operated high pressure water blasters.
Or add the Speedy Return Pack to your booking, then you can drop off your campervan as is and no cleaning is required.