> Similarly, unless you hammer the private sector with mandates it'll never build solar panels atop parking lots? Things can be expensive until lots of people

> Similarly, unless you hammer the private sector with mandates it'll never build solar panels atop parking lots? Things can be expensive until lots of people do them and then become cheap. > I'm all in favor of abundant energy for human consumption, especially if it comes from low-externality source, but I do question how much the needle is going to move by mandating solar panels on parking lots, which carries with it its own externalities. France has about 38 million cars. If there are 19 million car parks that qualify at 40m^2 each or 1.4kW, that's 26GW (so about the level you want solar at in your mix with the rest from wind/nuclear/hydro imports/etc