What's different about the Solar Roof then that might attract people to install them? Musk does have a few cards up his sleeve that his solar power predecessors didn't.
First, the SolarCity tiles are designed not to look like anything else than than roof slates, unlike the previous products and you can get them in a different colour than black, and four different designs.
There's also the new PowerWall battery to go with the slates, which now has 13.5 kilowatt hour capacity and costs US$6,500 including estimated installation costs in the United States. Again, expect the price to be higher in NZ.
Getting power and lines companies (hello Vector!) into the Tesla fold is a stroke of genius by Musk though.
The Tesla brand is recognised worldwide and the marketing angle of having your cake and eating it - driving a car and using electricity in your house with less greenhouse gas pollution - might work better with affluent customers who can afford the Solar Roof and Tesla vehicles.
You give up none of the convenience and comfort you're used to, yet you become part of the movement away from fossil fuels and toward electrical power. What environmentally conscious middle class person can resist that marketing push? Besides, countries in Europe are starting to get serious about banning petrol and diesel car, going fully electric vehicles only within the next decade.
Getting power and lines companies (hello Vector!) into the Tesla fold is a stroke of genius by Musk though.
Power and lines companies are ideal distributors for Tesla products (and might use the industrial batteries themselves), can assemble the installer forces needed, and have a vested interest in the move to an all-electric society.
Replacing fossil fuel energy will replace heaps more electricity generation, and solar is seen as the pollution-free magic bullet (it isn't) to deliver us into a new era.
In the midst of that, here's Elon Musk and Telstra doing a package deal for power and lines companies to get the fully electric society show on the road. I'd say the likes of Vector are very interested in that proposition.
The whole thing depends on Tesla's ability to deliver on its promises though, including making the actual products like the Solar Roof which isn't ready for delivery and installation yet.
We'll see how far Musk gets with his hugely ambitious concept, but you have to admire him coming up with it.