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livingchoice's avatar

How many 64 watt Solar Panels do I need?

Asked by livingchoice (553points) April 8th, 2011

I’m planning to power my home using 64 watt solar panels. My average electricity usage for the month is 207 kWh. This was obtained by adding up my past 12 electricity bills and dividing them by 12. I want to know how many 64 watt solar panels I would need to supply my home with power.

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12 Answers

RocketGuy's avatar

That’s 207,000 W-h per month, or ~6800 W-h per day. Assume 10 hr of sunshine per day, so you will need 11 panels at 64 W each.

Tropical_Willie's avatar

There are efficiency issues, like only getting a small percentage of the wattage in DC to convert to AC. The rest going to heat…. etc.

LuckyGuy's avatar

Are you sure that is all the electricity you use. At 15 cents per kWhr that comes to $31 per month or $372 per year. Is that your typical bill?
You will need more panels than the minimum. You need to cover peak draw. Will you do that with battery? You might need 50% more panels. 18 will give you 1152 Watts. That is not a lot but maybe enough if you have batteries.
What will the panels cost you? What payback are you expecting? 4 years? 372×4= $1488. Can you buy the 11 panels, inverters, batteries, regulators and switches for that price? Do you have sunlight for 10 hours per day, 365 days of the year? Important questions for you to answer.

tedd's avatar

If you’re serious about using alternative energy, look into making a miniature wind-mill. There are easy how to guides, the set-up is less complex than a solar panel (assuming you were going to make them yourself because they’re incredibly expensive), and pending the motor you put in it they will kick out 300–600 watt’s (and that’s a small in-you-back-yard size).

gorillapaws's avatar

You may also want to consider supplementing your plan with geothermal for your heating/cooling needs. It is pretty damn efficient and would reduce the need for solar power significantly.

critter1982's avatar

If your looking at wind energy you really need to get a wind analysis done and or look online for ones in your area which will show you if this is even a viable option.

livingchoice's avatar

Thanks all for your responses. You have really sparked my interest here. See my replies below

@worriedguy my bill comes on average $50/month. Should have about 10 hrs of sunlight per day. Planning to make these panels myself one by one. Each 64 watt panel will cost me under $100 in parts to build.

@tedd Do you have any suggestion on sites with miniature wind-mill plans that are easy to set up? Can you give an estimated supplies cost for one windmill?

@gorillapaws what is geothermal and how does it work. A link will be great

Thanks again.

livingchoice's avatar

@tedd Thanks for the link, some great info here. Have you built one of these?

gorillapaws's avatar

@livingchoice so the ground stays a fairly constant temperature year-round (I think it’s in the 50’s F). Water is pumped through coils in the ground in your back yard to either heat up or cool down depending if it’s summer or winter. This is used to reduce the amount of heating/cooling your system needs to do in order to heat/cool your house. It’s expensive to install initially, but will dramatically reduce your energy needs for heating/cooling your home. I would guess that this would likely make a large impact on the amount of solar energy you’d need. Here’s a link to the wikipedia article.

tedd's avatar

@livingchoice Sadly no, no place to put one.

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