I wonder how fuelly is adapting for electric cars? Will users input "miles per charge" and have kwh calculated? It will be hard to calculate charging costs I should imagine.

This time of year in the summer, my consumption is 0.14-0.15kWh/km. The charging from the outlet to stored energy in the battery is about 85% efficient so about 0.17kWh/km from the socket. At a rate of 1.4sek/kWh that means the cost/100km is 24sek. That converts to about $4,5/100miles in electricity. Compared to the cost of diesel here that is $13/100miles. Charging the car from the 4,7kW solar panels on the roof: $0 :)

But there is another issue: The fossile fuelled car uses 3-10times as much energy. Typically 3-4times for modern small cars such as diesels. If you would grow bio fuel to drive a car you would need 100times the area compared to driving an electric car charged by solar panels. So my conclusion is if we want to continue driving cars it's going to be electric. Neither fossile fuel nor bio fuel is sustainable for driving cars. It could be used to power ferries and maybe even trucks but the internal combustion engine is not efficient enough to allow everyone to drive a car.

It's interesting to see how the car market is developing, I went to the Goodwood festival of speed last month and every manufacturer there had future upcoming models of petrol/diesel and electric. I think fully electric cars at the moment still only suit short city trips, apart from the Tesla, which is the only electric car with a reasonable range at 275 miles. But even then, you'd still have to recharge it more than once on long trips.

On saying that, petrol and diesel cars are also being developed and becoming more and more efficient with lower emissions. The New Peugeot 208 just got 144 Mpg when tested, so for the average person, they would only need to refuel a few times a year.

The ICE will never match the efficiency of an electric motor. Toyota's new turbo diesel for light trucks, a 2.8L, has a thermal efficiency of 44%. Compared to an electric motor where an inefficient one is 85%.

Now, the losses of converting chemical energy into kinetic that ICEs have is paid for electricity back at the power plant. CCGT natural gas plants have 50% plus though, and they spend more time in that efficient range than a vehicle's engine does. In places where the power plant also supplies residential heating, I think Norway is one, the CCGT plant reach efficiencies of 90+%.

Then if you are getting your electric from renewables, the generation losses just become less of a concern than with fossil fuel and even nuclear plants.

Fixed for you

I'm curious how much your power bill has increased after both installing the solar and buying the electric car. My gut tells me that even an array of that size (quite large for a residence) will not give you a full charge daily on a Leaf. I'd guess it would only be possible for a couple of months in the summer when the days are long and there are few clouds.

They will be included in the new house we're building but the calculations say they will give around 5000kWh/year. The excess energy produced is sold on the grid for about $0.12/kWh slightly less than average price on bought electricity. They actually produce the most energy during spring/fall than hot days in the middle of the summer due to increased temperature inside the panels.

Price for an installation that size is around $7000 here. The nice thing about charging the car at home when you produce your own electricity is that more energy can be used locally rather than selling it back on to the grid. The best thing is you never have to stop for gas at a petrol station. Just a few seconds to plug the car in and charge when you are parked.