Solar for Heat... Ouch!

Came across this site that gives you a formula to determine the amount of solar panels you would need to replace current needs:

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.

A back of the envelope calculation shows that 39,000 watts of solar panels would take up approximately 3,100 square feet of space (about 55 by 55 feet) and weigh in at over 7,500 pounds.

Almost forgot, don't forget the maintenance, they have to be cleaned regularly or they lose efficiency.

I'm being generous, just to throw one more calculation in here for a realistic situation you would need to adjust for the lowest month which is December at 2.32 for "full sun hours you get per day". Actually you would need to adjust to lowest day but lowest month is close enough:

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( ( ( 3663 / 30) / 2.32 ) * 1.15 ) * 1000 = "60,523 Watts of solar panels"  

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60,523 * 4.31 = "260,854"  

$260,854 ... anybody have 1/4 of million they don't need?

I'm sure the treehuggers & Al Gore would be happy to spend that amount to save the world. Wonder why we haven't seen any stories about the installation of this many panels??? I thought it was about the earth, an NOT about money??? Where's Obamas ...... wait ..... that'll be even more taxes ........... scratch that .......

All treehuggers are hipocrites. You either want to save the world or you don't!

SMITTY wrote:I thought it was about the earth, an NOT about money???

If you saw the amount of toxic materials and waste manufacturing that stuff produces you would realize that it isn't about the earth, it's the MONEY.

If you saw the amount of toxic materials and waste manufacturing that stuff produces you would realize that it isn't about the earth, it's the MONEY.

I would like to see, got a source?

Most of the current solar cells are produced from crystalline semiconductor material. The actual cell production is not much different from any integrated circuit chip manufacturing. Assembly into panels is much like any other light manufacturing process. Not especially hazardous. See:

http://www.skcinc.com/instructions/1702.pdf

and

http://www.osha.gov/SLTC/semiconductors/index.html

for information about the semiconductor chip manufacturing hazards.

Also note there are other types of solar cells with entirely different manufacturing methods. The links above refer to the highest efficiency cells, the kind that would be used on spacecraft or anywhere you need the highest output per given area. Other solar cells are made in a process similar to printing.

Not especially hazardous.

Thanks Yanche that's what I thought.

dll wrote:

Not especially hazardous.

Thanks Yanche that's what I thought.

Just so you don't get the wrong message. Assembly of finished silicon solar cell chips into panel assemblies is not particularly hazardous. BUT manufacturing the silicon solar cell chips, including any silicon chips, i.e. microprocessors etc. IS hazardous. When I lived in Cupertino, CA the heart of silicon valley the concentration of chip manufacturing facilities in a highly populated area was and still is a major concern. Many of the gases used in doping the silicon is extremely hazardous. The major concern is transport of the gases from the gas manufacturer to the chip manufacturer. A lot of money is spend to assure safety.

Before the EPA and OSHA laws were in force I was working for a company that along with other toxic materials had zinc plating solutions that contained cyanide. The plating department was located on the top floor of a 6 story building. This did not make much sense from an industrial engineering point of view and when I asked about the placement they told me that WHEN there IS an EXPLOSION it will only take out the top floor and not the whole building. This operation had many accidents and at least 3 deaths over a period of 10 years. It is now out of business.

A lot of money is spend to assure safety.

After I felt there I spent over 20 years working with and holding responsibility for EPA and OSHA compliance along with my engineering duties. Some of these companies had full time people just working on compliance. The products these companies were making contained toxic materials like lead, cadmium and zinc along with metals like copper and gold.
By EPA laws we had to continuously monitor all our discharges and account for every pound of material that entered the operation and how it left. By law every bit of solid waste had to be captured and sent to reprocessing centers. With the OSHA laws we had to be handling the materials in a safe manner along with educating the workers on how to handle these materials.
We were blessed with unannounced visits from the EPA to make sure we were in compliance and not dumping. Any violation of EPA laws resulted in very stiff penalties and some companies were even put out of business for non-compliance. OSHA was the worst, they would hit us with a $500 fine for having a broom leaning against an electrical panel.

My experience with the state of CA was through the MSDS sheets. At the end of most MSDS sheets was a list of ingredients that were "Known to cause or linked to cancer" but only in the state of California.

There is a place for everything, for heat I will use coal but for walkway lights you just can't beat solar.

I'm not suggesting that someone would actually do this especially in this area, you'd have to be crazy. The point of this exercise was just to show how impractical it would be. If I was going to invest in a renewable source in this area it would geo thermal but I couldn't do that in my current house either.

Larger systems are much better suited in a sunny region and I would imagine it would be more practical to size the system as supplemental source. Seems the smaller the application the more practical it becomes, we had some walkway lights that were solar and they worked great... no cords so installation was dirt simple, lasted into the night long enough that it wasn't until late they would go off.

Solar certainly has a place in the energy world but primary source is not one of them for both economic and practical reasons. I wouldn't have enough space in total to place these let alone suitable space.

Very impractical for my area. Would be fine in southern AZ, I suppose ....

Solar works great for my Texas Instruments TI-30XA calculator!

if you are really serious about solar forget the cells go evacuated solar it is the best bang for the buck. Go to royallfurnace.com it is hotwaters sister.