content: I have a feeling he is talking price of the supplies and shipping while ignoring installed. The lighter weight would reduce shipping and durability means less breakage so you don't have to buy extra to account for that and less weight again. The problem is that with solar tiles you will have to add an electrician and wire it into the house's power and the grid plus have inspections for that. You will also have to have them test each tile before it is hooked up slowing the whole process down, this has to be done one by one as all together you can't tell if there are some not working or just a bit of shade on part of the roof. Install is going to cost probably 2x as much as a normal roof if it is done correctly.