Thursday, April 22, 2010

Happy Earth Day, living and driving on sunshine.

Happy Earth Day, living and driving on sunshine.

You can live in a home and drive a car powered by sunshine. In our case we live in 3300 sq ft home with a 1000 sq ft guest house and drive a BMW Mini-E 16,000 miles a year.

All powered by sunshine via a 7.5 kw Sunpower solar PV system :)

We have a net metering agreement with SDG&E that allows us to pay once a year for the energy for our home. For the 2010 year we estimate our total energy use will be between 0 and $100. There is an outside chance we could be below zero but it's a rainy year so I think not.

In the early part of the year, January through March, we use more energy than we produce and we have a bill. In the mid part of the year from mid March to October we generate more energy than we use and we have a credit each month for 6 months. In November and December we again use more than we generate and we have a bill. At the end of the year we are essentially energy neutral or net zero.

In actuality the home produces far more energy than it consumes because it is also supplying 3500kwh, the equivalent of $2000 of gasoline annually to power the Mini-E.

This is our most current bill and you can see that we started at 70304 and ended at 70297. a -5 KWH usage for the month. The normal SDG&E bill does not give you credit for generation so the top lines of -270 and -75 show 0 when in reality you get paid for that at the higher peak rates.

This is the net metering bill that you keep track of the year with. It comes together with the normal bill above. You can see in January and February we had a bill of $102.42 and $65.49 and then in March we dipped below zero and have a credit of $-11.72 and a total KWH usage of -5

From now until October we will have a credit each month. In May the summer rate structure begins which is far better for us as far as getting paid for solar production and we will have credits around $40 to $60 per month. The below chart is an approximation of how our year looks.

The Solar PV system is now two years old with the new "gas station" addition 8 months ago. We have generated almost 20 megawatts of energy with a value of $8500 in electricity and gasoline. This represents around 35% of the total system cost ($26,000) and puts our break even point at around 6 years, less if electricity rates or gas rates spike. Less if you fiqure the HELOC loan interest is deductible off your taxes and the sdge bill is not.

Remember, this is 6 years of the same payments you are already making to SDG&E and you local gas station, it's not a new payment.

How can anyone afford not to do solar.
Cheers and Happy Earth Day!


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