Wednesday, April 29, 2009

More Numbers

It's been a sunny week here in Maine, and so the Barn has been creating lots of electricity. I decided to check all the numbers again, and compare them to those at the last post, on April 20.

Today at noon the Barn's total production since go-live was 2745 kilowatt-hours. That means that in the past 9 days the PV panels have pumped out 224 kwh, or an average of almost 25 kwh each day. Usage has been modest, now that the cold weather is gone, with air handling, lights, and computers accounting for most of the load - and with the longer days, light usage is going down noticeably. Total usage to date has been 970 kwh, compared with 953 kwh ten days ago, or only 1.9 kwh of electricity used per day.

This means that the current difference between electricity generated and electricity used in the Barn stands at 1775 kwh surplus, meaning that we have put a net of 1775 kwh out on the grid over the past 6 months. The past 9 days alone have accounted for 207 kwh surplus, or about 23 kwh per day on average.

This contribution to the grid helps pay off our carbon debt incurred in the making of the Barn, at the rate of one to two pounds of carbon per kilowatt-hour, depending on the major source of the electricity on the grid. So we appear to have knocked approximately one metric ton of carbon off our debt, even through the depths a cold Maine winter.

And since our main house is just "upstream" of the Barn, we get the benefit of most of that surplus electricity, which is lowering our electrical bill substantially. Last month, our bill from Central Maine Power was only $11.00.

Here's hoping for a sunny Spring!
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