ORLY? Odd that an energy company puts such a high emphasis on quarterly delivery numbers of... automobiles.
I actually think the residential solar roof market will remain niche, and the fancy integrated solar roof will be effectively a luxury product with a relatively small market value.
However, look at that huge Kauai solar/storage installation: http://www.theverge.com/2017/3/8/14854858/tesla-solar-hawaii...
Tesla (with acquisition of Solar City) is able to turn these commodity solar cells from other companies (now at just 19 cents per Watt: http://pv.energytrend.com/pricequotes.html) into profitable utility-scale installations very quickly and at scale. They can install them all over the developing world where electricity demand is soaring and the existing sources are expensive (i.e. diesel). A key to this is the ability to install FAST. They can install these utility-scale battery storage units in just 3 months vs 3 years for a natural gas fired power plant (vs 4-5 years for coal, 6-20+ years for a nuclear power plant). And they can work with any kind of existing or future electricity source, smoothing out peaks in demand, including advanced combined cycle natural gas plants.
So that's a huge market especially if you can tack on a solar farm on top of it. And their exposure to risk on the very low-margin solar cell manufacturing side is limited, as Solar City primarily uses whatever cells the market produces, not their in-house stuff. It has even less competition than the "non-sucky production electric cars" market, and with the 3rd world needing terawatts of electricity, the market will only grow.
But they seem to be leading the way in battery production and self-driving automobiles. If they can hold on to market lead in those two areas then they should still be able to way outpace Ford or other car manufacturers. Big IF though in terms of self-driving technology with all the other big money players racing for that grail. Energy storage and battery production they seem to be in a class of their own without much competition.