http://www.solar-electric.com/solar_system_costs.htm

# First, take number of KWH shown on your bill. Divide that by 30. That gives you your average daily usage. So if you use 700 KWH, that is 23.3 KWH per day.

# Take that number. Divide it by the number of full sun hours you get per day on a yearly average. Multiply it by 1.15. That will give you a pretty close estimate of how many watts of solar panel you need. So if you get 5 hours per day, divide 23.3 by 5 - that gives you 4.66 KW, or 4,666 watts. Multiply that by 1.15, which gives you 5,360 watts of solar panel needed.

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`( ( ( "kWh per month" / 30 ) / "full sun hours you get per day on a yearly average" ) * 1.15 ) * 1000`

The "full sun hours you get per day on a yearly average" number can be determined here:

http://rredc.nrel.gov/solar/calculators ... /version1/

After you go through the steps under the column "Solar Radiation" in the second table you want the yearly average down the bottom. For Wilkes Barre ,Pennsylvania it's 4.18. The formula would look like this if you're using 1000kWh per month.

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`( ( ( 1000 / 30) / 4.18 ) * 1.15 ) * 1000 = "9170 Watts of solar panels needed"`

The US national average per watt for solar panel is $4.31 this month, It should be noted that the bottom of market for solar panels bottomed out last year and apparently hasn't recovered yet. The average cost prior to that was about $4.80 per watt for many years.

So to meet the electric needs alone for a house using 1000kWh per month:

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`9170 * 4.31 = "$39,522"`

$39,522 That's quite a shocker... now lets move onto if you wanted to make heat.

Since we'll need to make heat in the winter we'll need to adjust "full sun hours you get per day on a yearly average" since we get so much less sun in the winter. When we exclude the months of May through August the average gets lowered to 3.59.

5 tons of coal per season seems to be the rule of thumb for 2000 sq. foot home so we'll use that to base how much heat we need to generate. Adjusted for efficiency let's say net output is 20,000,000 or we need generate 100 million BTU's to heat the house. That 100 million BTU's averages too 12,500,000 per month in our 8 month period.

You can make 3,412 BTU's per kWh using standard electric heating. Soooooo....(have I lost you yet?) We first need to see how many kWh per month we will need to generate same heat:

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`12,500,000 / 3412 = 3663 kWh per month`

So going back to our original formula and adjusting for the 8 month period:

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`( ( ( 3663 / 30) / 3.59 ) * 1.15 ) * 1000 = "39,112 Watts of solar panels"`

Now we factor the cost of the panels:

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`39,112 * 4.31 = "$168,572.72"`

$168,572.72 Yikes! I believe the life of solar panel is about 30 years as they slowly degrade over time but even if they operated at 100% over 30 years you're looking at a figure of $5,600 per year to provide heat with photovoltaic solar for a 2000 sq. foot home in Northeast Pennsylvania.

To that cost we still need to add in the cost of installation, battery backup which is probably considerable amount because you would need to be able to store the electric and I'm sure there is other costs involved over the life of the panels. Also note I'm not sure if $4.31 per watt is assembled panel ready for installation. Lastly this is just for heat, if you wanted to do electric you'd have to factor that in too.