> They fold up in use, so the drag hit probably isn’t that much. The folding is a huge square box on top of the car, so the drag definitely increases a lot. J

> They fold up in use, so the drag hit probably isn’t that much. The folding is a huge square box on top of the car, so the drag definitely increases a lot. Just a roof rack will have a minor but noticeable impact on drag, a ski box is 10~15% efficiency loss (http://kootenayevfamily.ca/model-3-roof-rack-consumption-test/ http://kootenayevfamily.ca/model-3-roof-rack-consumption-tes...). This is the worst designed roof box in history, I'd say 20~25% efficiency loss is lowballing it, unless it's only ever crawled at urban speeds, slow enough that drag is not relevant. > If he’s getting 5-20kWh per day AFAIK the best panels are circa 25% efficient, so 20kWh/day is not even within physical plausibility, let alone actual. I don't know if they were ever tested by independent third party, but FWIW Lightyear's estimates for their 5sqm curved solar panels (so no loss of efficiency) was 70km/day best-case (at the height of summer, with the car in full illumination at all time), at 96Wh/km (advertised WLTP) that comes out to 6.7kWh. Again, best-case, and without a Cd hit.