Discussed before: https://news.ycombinator.com/item?id=48165980

Solar shingles (Tesla roof, GAF) seem like a smart idea -- why do 2 layers of install, shingles and solar panels, instead save on both material and labor by using solar shingles.

It didn't work because the shingles are small, massively increasing the number of parts, connectors, and wiring -- and all the intensive skilled labor that it needs. Labor needs to be skilled as well as increases the number of hours. It also increases failure rates (at install time?) as well as lifecycle maintenance costs from repairs. Standard shingled roof (not the solar) is just an illegal immigrant working for $2/hour with a nail gun, unskilled labor, finishes things super super quick.