off topic but are charging stations in public areas free?
As to carport solar roofs, consider about 1KWh per square meter per average day on an ideally situated location...you aren't charging very many vehicals from the rooftop alone.
A friend has 2 Tesla Model S cars. He also has 10KW of grid tie solar on his home. The 10KW worth of panels produce a peak of 8kw power at noon. (some losses in the inverters) Also, in our Florida location, the annualized sunlight is 4.7 hours of sun per day.
The bottom line is that the 10KW installation completely offsets his motoring expenses. Excluding the very high vehicle cost, the fuel savings payback is about 7 or 8 years.
Assuming he paid for the panels himself, that's roughly $300K (cars + solar). Somewhat ironic that somebody who can afford such a setup is, financially, the least in need to benefit from it.
This is of course in-step with everybody I know who owns a Model S and those that own grid-tie solar. None of these people's lifestyles are being impacted by the increase in electricity costs but saw an opportunity to benefit from government subsidy (FIT and EV seeding).
Isn't that the way it goes with most things? Those who can afford it enter first, then tech transfers down as costs reduce?
Tech doesn't show up in the smart car first, it shows up in the S class.
Tech doesn't show up in the chrome book first, it shows up in the high end business and gaming laptops.
Tech doesn't show up in the loss leader appliances, it shows up in the high end kitchen appliances first.
And so on.
The fact that economics is a consideration here is not really a factor. In this case money buys economy as well as some other untangible factors which if feel good or bond fide benefit, is those who have money's to spend.
