Good News

I read today in the Oakland Tribune that SunPower, Silcon Valley's largest solar manufacturer, has teamed up with Ford to offer a special price for installing solar for people who buy the Ford Focus, due out later this year.



They are offering a 2.5 kilowatt rooftop system for under $10,000, after tax credits, or about $14,000 before credit. What I like about this is that it simplifies the process--buy a car and get the solar all as a package deal. One of the things I have to admit about our installation last year is that I would not have had the time to deal with it when I was working (I'm retired)--getting bids, trying to select a contractor, reading up on Yelp to see who I liked, etc. Of course, our job was complicated by the need to replace our roof and upgrade our electrical system at the same time as we got the solar system. I'm not sure if SunPower will handle all of that as well for people who need it., but that would be nice.



Just to run the numbers a bit more: The Tribune article states that the Ford Focus can travel about 1,000 miles per month on the 2.5 kw system. Now our 3.2 kw system generates about 4200 kwh per year. So, by proportion, a 2.5 kw system would generate (2.5/3.2) x 4200 = 3281 kwh per year, or 273 per month. That means that Ford is expecting the Focus to go 1000/273 = 3,7 miles per kwh. By comparison our Volt is getting about 3.3 miles per kwh.



What the article doesn't explain, but what is very important for solar power and electric cars, is that the PG&E E9 rates are much cheaper for charging at night compared to what the solar power is paid for during the day. So the 3,281 kwh of solar power are worth $0.28 per kwh in peak summer hours during the week, $0.10 in the partial peaks and in the winter, and $0.04 for most of the weekend, so we earn about 13 cents per kwh for our solar.



Meanwhile the 3,281 kwh that the car needs can all be generated at the off peak rate of $0.04, if you have a 220 volt charger that can charge the car in 4 hours. If you charge the car with 110 volts, it will take more like 11 hours to charge so the cost will be around 6 cents per kwh combining off-peak and partial peak charges.



So you earn 13 cents per kwh, but you only pay 4-6 cents to charge the car--i.e. a net profit of at least 7 cents per kwh. Take that times 3,281 and you have a savings of $230 per year on your electrical bill. Now the cost to finance the solar panels with a 30 year loan at todays rate of 4.4% would be $600 per year, with a lock against increasing costs of energy over the years. That $230 should be added to the savings on gasoline that you get with an electric car--less than 2 cents per mile for an electric car vs. 10 - 20 cents per gallon for gasoline depending on your mileage and the constantly changing price of gas.



Of course I would urge people to go ahead and buy a big enough system to zero out their PG&E electrical bill (except for fixed charges). The more solar the merrier! For the 300 kwh per month that our house uses, plus the 250 kwh that the Volt uses, a 3.2 kw rooftop system does the job.