Funny,
I got a call from Tesla energy last year and was told that based on our very low rate in Southwest Washington (just over 8 cents/kWh) that it would take 85 years to break even on a Tesla Roof.
I have thought about getting solar, but thought the payout time would be something like that. We get most if not all our electricity from renewables now. One set of lines coming off the North Bonneville Dam run along the hill above our house.