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Friday, December 29th, 2006

solar electric: third anniversary

We closed out the 2006 “trueup” billing period with a disappointing $94.48 charge, after the ~$65 rebate for “distribution” fees we already paid. So our total out-of-pocket for the year’s electricity was about $160.

Our production was down this year, most likely due to shading; we generated only 3440 kWh in 2006, as compared to 3898 kWh in 2005 — a 12% drop. The graph of our monthly power generation makes this clear. We’ll be trimming some trees here in the near future in hopes of regaining some of our late-afternoon sunlight.

The graph of monthly unbilled charges is interesting. As it is based on fees, it reflects both generation and consumption; an expensive month could be due to low generation or to high usage, or a combination. We started 2006 well, beating our 2005 rates, but for the middle six months of the year we lost all early gains. The middle months were dismal; we didn’t build up nearly enough surplus to ride out the Fall. In fact, we didn’t come near to the zero line, much less cross it as we did in the summer of 2004 (when our final trueup bill was a mere $6.53). I’m looking forward to some additional conservation measures for 2007.

To put this in perspective, I’m quibbling about numbers in a way that masks the awesomeness of photovoltaic power generation. The critical takeaway is that we produced 50%* of our own electricity this year, and prevented 4544 lbs of carbon dioxide from being blown into the atmosphere on our behalf**. I feel good about that. Even better, we produced 100% of our peak-period electricity, plus 544 kWh surplus, which creates disproportionate benefits to the stability of the grid and to atmospheric effects of fossil-fuel power generation.

Previous anniversaries: 2005, 2005 breakeven calculation, 2004.

*The TOU meter-reading data on the trueup bill shows we burned 3413 kWh, but I believe that is the total after deducting the 3440 kWh we produced, as the meter runs backwards when the sun shines.

** “The output rate for CO2 from natural gas-fired plants in 1999 was 1.321 pounds CO2 per kilowatthour.” 3440 kWh * 1.321 = 4544 lbs.

Tags: photovoltaic, trueup, solar, pv
posted to channel: Solar Blog
updated: 2006-12-31 22:03:19

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Carbon neutral for 2007.