https://www.cnet.com/news/tesla-solar-roof-production-to-ramp-up-in-2019-says-elon-musk/

"There's a lot of engineering that goes into how do you put on the solar tile roof, but with, and not be really labor intensive in doing so. So there's a lot of engineering not just in the tile, but in the way it's done,"  Musk said in the call. 

The company says the Solar Roof will cost $21.85 per square foot of Solar Roof tile for a 3,000-square-foot roof, using the same calculation method in a Consumer Reports roof tile comparison from November 2016. To compete with the costs of a non-solar roof, Tesla, extrapolating from the Consumer Report study, said the Solar Roof would need to come under $24.50.