jjeff said:
Cool, looks like the Japanese version of the Prime will get a solar roof, which they say on a sunny day could give you an extra 3.7 miles, which wouldn't be a lot in a BEV but on a vehicle that only had a 25 mile EV range, every bit would help.
https://thinkprogress.org/prius-solar-roof-breakthrough-2b929f467061
That seems to be big enough to be marginally useful instead of purely a gimmick like the LEAF's, although what the price is will be the determining factor. Still, as someone who often leaves my car sitting at a trailhead for hours or days, not to mention in my driveway for a week or more, it might pencil out. Course, you'd have to deliberately leave the car so it was exposed to the sun all day instead of parking in the shade, so there'd presumably be some (battery and/or cabin) cooling overhead that would eliminate much of the charging benefit. I suspect that until the entire surface of the car is covered with cells at an affordable price, this won't be cost-effective.