I think Elon got ripped off on his last shingle roof. The bar chart is nice but off by at least 150%. I've had many roofing subcontractors as clients past and present in Northern California. Based on an average of 870 roofs in 2016 for Single Family Residential homes in the bay area, Asphalt shingle roofs are $3.12 per square foot for materials and labor. The highest was $5.75 psf and the lowest $2.35 psf. Note that the SF bay area is considered one of the most expensive in roofing market. Also note that Solar City has a poor reputation in the industry for hard selling larger than needed residential solar systems.