Sunday, June 6, 2010

Solar Investment

A “typical home” in America can use either electricity or gas to provide heat — heat for the house, the hot water, the clothes dryer and the stove/oven. If you were to power a house with solar electricity, you would certainly use gas appliances because solar electricity is so expensive. This means that what you would be powering with solar electricity are things like the refrigerator, the lights, the computer, the TV, stereo equipment, motors in things like furnace fans and the washer, etc. Let’s say that all of those things average out to 600 watts on average. Over the course of 24 hours, you need 600 watts * 24 hours = 14,400 watt-hours per day.

From our calculations and assumptions above, we know that a solar panel can generate 70 milliwatts per square inch * 5 hours = 350 milliwatt hours per day. Therefore you need about 41,000 square inches of solar panel for the house. That’s a solar panel that measures about 285 square feet (about 26 square meters). That would cost around $16,000 right now. Then, because the sun only shines part of the time, you would need to purchase a battery bank, an inverter, etc., and that often doubles the cost of the installation.

If you want to have a small room air conditioner in your bedroom, double everything.

I’ve been monitoring the usage of my house, and we consume about 10 Kilowatts per day (STEEP!!!). Now, in order to have solar panels for that, i would need a number of panels, from this site, i picked one at random, which produces 170 watts for an investment of $839 per panel. A quick calculation (from the data provided on the site), tells me i need atleast 6 of these panels to power my house meaning an investment of $5034 (or Rs. 3,02,040) without addding any sort of tax or extra charges on the modules and i need a space of about 30×15 feet to house it. (again from data provided for this module).

Now the KESC rate for domestic supply is about 7.5 per kilowatt (at their lowest slab), meaning that my monthly electricity bill becomes 2250 (without the charges, surcharges, and extra surcharges :S).

So, just on these ideal figures (just the power usage, no infrastructure costs), it would take me about 135 months or about 11 years just to breakeven the cost of the cells.

I think we should wait another decade or something, or encourage NEDians and other engineering universities to come up with solutions.. and let the prices fall down a bit. Its expected that the price will fall down to about 1/5 of what it costs now over the next decade.. which just may make this a viable option.

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