EV article in today's Oakland Tribune

The Oakland Tribune reprinted an article from the San Jose Mercury News today that featured Felix Kramer of Calcars.org. The article was a positive treatment of electric vehicles, and I was glad to see it.

However, the article still appears to be not aware of the off-peak electric rates that PG&E offers for charging electric vehicles. The article estimates that electricity to charge an EV would be around 3.7 cents per mile ($561 divided by 15000 miles). In reality the cost is closer to 1.7 cents per mile.

This means that the costs to charge the batteries for 15,000 miles would be $255, not $561 as the article claims.

Here is the arithmetic:

Last night our Volt showed 4 miles remaining on the battery when I plugged it in with the timer set to charge starting at midnight. When I got up, the car showed that it was fully charged with 39 miles showing on the battery. This was an increase of 35 miles. I checked the Chargepoint software today and learned that it took 10 kilowatt hours (kwh) to charge the battery last night. So dividing 35 miles by 10 kwh = 3.5 miles per kwh. This is fairly typical for our car in Oakland, but in areas where the car needs a lot of heating or air conditioning, it would be somewhat lower.

PG&E charges an average of 4 cents per kwh at night. They also charge $12 per month for meter reading and "minimum fees". This adds 2 cents per kwh--$12.00 divided by our monthly usage of 600 kwh = 2 cents per kwh. The PG&E rates are found on the following web site (but note that the rates shown in the tariff table receive a 1.7 cents per kwh credit, which brings the average for summer & winter down to 4 cents for the baseline rate.)
http://www.pge.com/tariffs/tm2/pdf/ELEC_SCHEDS_E-9.pdf

Dividing 6 cents per kwh by 3.5 miles per kwh = 1.7 cents per mile.

Note that I'm assuming our rate is within the baseline since our solar panels keep our total energy consumption very low. If you do not have solar panels, PG&E would charge the E9B rate by installing a separate meter for the electric car. Assuming you use 10 kwh every night to charge the car, that will put you at just over the baseline (about 9 kwh per day for where we live)