The whole house will take that long to pay for itself. Any new home that pays off earlier points towards a bubble.

So if you assume that it takes 30 years until the house has amortised (via rent or saved rent), why not assume the same for the solar roof?

Can't you get solar panels essentially for free and just pay for the generated electricity? I thought that was the business model of companies like SolarCity

I wonder how hard it would have been to have partnered with FPL so FPL puts up the capital for the panels, the resident pays their electric bill as usual, but a portion goes to pay back FPL for the panels. FPL is allowed to make, say 10% over on the panels.