Solar heating sounds nice in theory... but wouldn't that involve cutting a hole in the roof of the house for a solar panel? Maybe that's just the way I'm picturing it and there's another way? If that's it, I'm not sure we'd want to go that far to heat that room and would probably let it stay cold. Great idea and I like it, but I suppose a roof hole would cost more than we'd want to put into that up-to-now basically unused room.