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Solar Power Home

Frances Said:

How much watt or kilowatt is required to power a home?

We Answered:

Numbers vary all over the lot. When built, my house had a 400 amp service, but it had electric resistance heat as well as electric hot water and an electric range. All those appliances are now gas, so the load is down by probably 70% or so. So, I'll suggest an analytical approach.
- First, do you want a battery plant? Are you willing to draw powerline electricity in the evening, or do you want to be independent?
- Second, does your power utility support reversible meters -- will they buy your surplus juice? Or, do you want to be off the grid completely?
- Third, what kind of subsidies are available for your proposed system? If there aren't any, and you have grid electricity available, you will be far better off leaving your money in the bank: solar photovoltaic systems run about $10 a watt, and can produce at most 2 kWh of power per installed watt per year, which in most areas is worth about 25 cents.
I have a friend who installed a 1200 watt system three years ago. The list price was $13,000; subsidies brought this down to $5,000, and friend did $1,000 worth of the installation work. The system has produced 2900 kWh per year, worth about $300, so it is marginally profitable. It is situated Redwood City, Cal, so it gets good sunshine.

Now, for the analysis: Add up the power loads you expect to feed, multiplied by the hours per day that they actually are running. That will give you your daily demand in kWh. Check this with a recent electric bill, dividing the monthly consumption by 30. That, with the other information I have suggested, should give you an overall sanity check on the program.

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