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Solar Panel Question?

My electric bill per month averages 800 kWh per month. I am looking at 65W solar panels. How many panels would I need to make my bill come to zero? I realize I also need an inverter to convert dc to ac.

Answer:

There is always a lot of confusion on this question so I built a webpage to show people how to do the math and pick the right system size. Most all public utilities will trade you kWh for kWh and then either settle up with you at the end of the month or every 2 months. So one week you might have all rainy days but the next 3 weeks you have 0 hours of bright sun even in the winter. This means you have no need to put batteries on your system unless you have a lot of power outages. Then you only need a few hours of battery backup power. At most 24 hours.
It depends very much on where you live. If you live in Nevada, Arizona or California solar panels might be a good idea. If you live in Canada don?t expect to get your bill to zero... 800 kwh/month means an average consumption rate of about 2500 watts. 6 panels would cover that. But your energy consumption isn?t cosntant and nor is your energy production from the solarpanels. If you go off to work during the day when your panels produce the most then you probably produce excess electricity. Check with your utility if it is possible for you to sell off that electricity by putting it on the grid. Then you buy back electricity when you?re watching tv and surf the web at night. You loose money and electricity like this (or by using batteries as suggested above) so I would underdimension my solarpanel capacity. It makes sense if it is cheaper to just buy electricity at night. The retailer and the manufacturer should have charts showing how much their 65 watt panels really produce at different times of the day and the year for your location. Oh, and I?m sure there are ways in which you could reduce your electricity consumption. Smart lights, energy efficient lights are easy ways.
Your local installer will estimate this much more precisely than I can. Your main problem, as I see it, is not that you need this many solar panels. Your main problem is that you consume WAY too much electricity. You should probably cut your energy consumption in half BEFORE you invest in solar because it will be way more economic to eliminate the main consumers than to generate that wasted energy. I, for example, need no more than 80kWh/month for a household of two.
I like TBS0's answer, but 5KW isn't going to hack it. We don't live life on the average. If you turn on the oven, the dryer, the iron, a bunch of lights, and the TV, you are going to shut the system right down. You should not count on running everything with solar cells, but the most critical circuits. And you are lucky to have 25% of a day in optimum solar alignment for photocells. You need to think outside the Al Gore crazy box. Our modern way of life requires a lot of power! If you switched to coal or wood for cooking and heating and ironing, sunshine for drying clothes, heating the hot water heater, and for daytime lighting, then you could use the photocells for some lighting and the washing machine and anything electronic. You might stand a chance.
There are 720 hours in a month (30 days) but only about /2 of those are in *full* sun 800 kW hr / 360 hr = 5 kW. 5000 W / 65 W / panel = 30 panels minimum and that's based on full sun during the day (no clouds, rain, etc). Besides an inverter you'll also want a bank of batteries to operate at night. OR, you can get about 35 - 40 panels and sell power back to the utility during the day (meter runs backwards), and use power off the grid at night. Suprise! solar power isn't cheap, is it? Figure on taking advantage of some government and public utility rebates, though to lessen the cost. .

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