They warranty the glass of the solar roof tiles "forever" (weatherization and energy generation for 30 years). They are only going to install a limited number o

They warranty the glass of the solar roof tiles "forever" (weatherization and energy generation for 30 years). They are only going to install a limited number of test cases until they know exactly what percentage of them will last that long. The launch price -- $42/sq ft for the solar tiles, $11/sq ft for inert tiles that look the same -- is too high, and manufacturing yield is too low. Finally, the first few roofs they installed took a Tesla team 3-4 weeks. I've read a couple cases in 2019 that took 2 weeks. I think they need to get installation time down to a week before they want to scale that any further. In short, they probably lost money on every solar roof they installed in 2018, because that house is essentially acting as a real-world test bench. I think they will only install as many roofs as they need for testing purposes as they refine the design, manufacturing, and installation procedure. If and when they cross the 20% margin point at a price that's still a premium over a new roof + panels, but not eye-wateringly so, they will scale production and start actually working through their order book.