Saturday, September 05, 2009

My home project - Using less electricity

I'm now on a kick to use less electricity. Well, at least, to "buy" less electricity. On average, my house uses about 45KWH per day (around 1400KWH per month). Current electricity cost is around US$0.20 per KWH but this time last year I was paying closer to US$0.33 cents per KWH.

A few years ago, I put in a solar hot water system on my roof. At the time, that saved me about $50.00 per month, but is probably saving me more now.

Here is some guesses as to the major power consumers in my house:
  • 2 Dell T605 Servers - 6KWH per day
  • 4 Desktop computers - 5KWH per day
  • Pool pump (8 hrs/day) - 14KWH per day
  • Refrigerator - 5KWH per day
  • Air Conditioning (22 SEER rated at 7 hours day) - 3KWH
The electric bill itself does not bother me as much as the dependency on oil. Not that I'm an environmentalist or anything (I don't even recycle cans!), but from a political perspective I think the dependency on oil is a really bad thing.

I am planning 2 separate projects:
  • Replace the pool pump with an Intelli-Flow pump. These are supposed to use 75% less electricity. They run continuously, but at a signficantly lower horse-power/amperage.
  • Install a photo-voltaic system. I have proposals to install systems that produce between 6 and 32KWH per day. I'm probably going to go with a system that produces around 15KW per day, but can be expanded the second year with an additional 20KW of capacity. So the second year capacity would be around 35KWH per day. The initial system's cost is $28,000 but there are almost $19,000 in tax incentives to do this. At the current cost of electricity, the payback on this system is around 7 years.

If any of you did the math and are asking, wait a minute, if you are producing 35KWH of electricity per day, you are only producing that much during the sunny hours of the day (peak production for these systems in Hawaii is 9AM - 3PM though they will produce some outside of those periods. Your house is using electricity 24 hours per day.

Quite right. The final system that I'm looking at will produce around 8.3KWH (per hour). However, I'm not using THAT much an hour. In that case, my power meter runs backward and I feed electricity back out "on the the grid". The electric company can then use that electricity and (by law) has to give me credit for it. Then, at night, when I'm not producing electricity I can use back up the credits.

My ultimate goal is to produce about as much per day as my house uses. I can do that if I can improve the pool pump's efficiency. The initial investment is pretty high, but the system lifetime is 25+ years so the payback is tremendous.


At 7:32 PM, Blogger goabeauty said...

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