"When it's not plugged into the home the van's batteries are being charged by a 1-kilowatt panel on its roof and small panels on the sides which charge the indicators and lights."

I could see them adding a significant charge in morning/late afternoon when the sun is low. Im dont actually know though lol

You're correct. Only the roof is likely to give significant power. Been there and done that, on the opposite side of the planet though. :)

The "something" on the picture I attach... was built in some squat in Eastern Europe. It had a flat roof of approximately 2 x 1.5 m, all of it solar panel. Solar panels weren't great back then. Typically it charged its 4 KWh battery in a few days of sunshine. Only during midsummer (18-hour days) was there any chance of a full charge in a single day.

Unlike the van, the "something" required a smaller inventory of tools to build. Instead of lawnmower motors, a Chinese electric motorcycle motor was used. Sadly it's now retired due to metal fatigue. :( Lesson: never build a structure that flexes out of aluminum - aluminum has no fatigue limit, any flexing will lead to cracking.