I was thinking about this the other day actually. You can’t get enough power from panels on a regular car roof to do anything useful. A 100W solar panel typica

I was thinking about this the other day actually. You can’t get enough power from panels on a regular car roof to do anything useful. A 100W solar panel typically generates about 400 Wh per day, and has an area of 0.7 m², weighs about 8 kg, and costs about $100. Using the range and battery data for the Tesla S: A 200 km daily commute (i.e. an hour each way) you would require ~35 kWh, and require 90 100W panels, or 60 m², weigh 700 kg, and cost $9000. Possible, but only as a fixed install, not on the car’s roof! For touring, you could do 500 km per night (about maximum range for the 100 kWh Tesla S) and charge during the day, but would require 250 panels / 175 m² / 2000 kg / $25,000. You would require a trailer to carry them, and the set up & tear down each day would be laborious, but it would be possible and you could then travel indefinitely. A bit like what Mark Watney does in The Martian. If you were willing to spend multiple days charging for each 500 km leg, or only travel a couple of hours per day it would be even easier. Edit: I just looked up The Martian and Watney had 18 kWh of batteries for his rover, 28 m² of panels (with longer days but less power), travelling a max of 90 km per day for over a month. So yeah.