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Issue #216 July 2008
Intelligent Energy Solutions
Living And Working Off The Grid
Part 1: Planning And Design
by George Martin
Start | Power Usage | Estimating Solar Radiation | Equipment | Solar Panels | Inverters | Charge Controller | Battery | Miscellaneous Items | System Cost | Sources & PDF
POWER USAGE
I first needed to determine if the project was financially feasible. I started with our current electric usage. Typically, our electric bill is 24 kWh per day. It is more in the summer with air conditioning and also in the winter with more lighting, heating, and indoor living. This is about $120 per month ($1,440 per year) at current rates. To reconcile the bill with our usage for each appliance, I purchased a P3 International Kill A Watt meter on the Internet for about $30 and began to record the power usage for each and every appliance I could measure. It is a great little meter that measures volts, amps, frequency, watts, and kilowatt hours. I left the meter connected to major appliances for a week to get our general pattern of usage. Some appliances, such as the electric stove and heating system, could not be measured. The stove is 220 V and the heating system is hard-wired with no place to use the meter.
I next went to the Internet to get typical usages for items such as the dishwasher, clothes dryer, and oven. I then estimated usages for the oil burner, circulating pumps, and lights. Bottom line: I could account for 22.15 of the billed 24 kWh. I feel comfortable that I know where our current usage is spent. This data is in a spreadsheet (EnergyAudit.pdf) posted on the Circuit Cellar FTP site. How many kilowatt hours are you using? And where is all that being used?
I thought I had a handle on how our lifestyle consumed electrical energy, so I created a column for our new home. Actually two columns. One for phase 1 of the project. We’re building a workshop/apartment type home so that we can have a starting point for living out west and if we don’t like it, we can get out probably at no financial loss. So, one column is for the workshop and the other is for the final home. You can see some of the assumptions that we made for each. We need 7.9 kWh for the workshop and 11.4 kWh for the home. I look at these numbers with some reservation because we are not actually living out there and they are estimates. But on the positive side, appliances are getting more energy efficient each year, so new purchases should be less than what I’ve measured.
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