Below is the best calculator I have come across comparing the cost of gasoline, utility supplied electricity and Solar PV. It’s simple to use and you can customize the data inputs for your particular area. The picture is my scenario with our Solar PV cost and production, You can clearly see that the system cost for a lifetime supply of the "Ultimate Fuel" is less than the cost of buying gasoline for three years.
click on image to enlarge
The BMW ActiveE when paired with renewable energy is an unbeatable combination of the “Ultimate Driving Machine” and the “Ultimate Fuel”. In many areas of the country, the Pacific Northwest as an example, the "Ultimate Fuel" is provided by hydro via the utility company at extremely low rates of $0.06 -$0.10 per kwh. Pass go collect $200, you live in the perfect plug in world.
For many of us in the more sunny states (thus less water for hydro) Solar PV makes great sense as a fuel for your ActiveE. Renewable energy such as hydro, geothermal, wind and solar is simply the “Ultimate Fuel” for our light vehicle fleet whether provided by your utility or homegrown. The sooner we figure that out as a nation, the better off we will be, environmentally, socially and economically.
Many thanks to empulsebuyer for a great tool. Give the calculator a try, you might surprise yourself :)