Posted on 07/15/2003 3:16:56 AM PDT by Boot Hill
Here is what the acolytes of solar power don't want you to know...
These are the essentials you need in order to appreciate the absurdity of using solar cell power systems as any kind of sensible alternative. After you read this, ask yourself again how much sense solar power really makes.
THIS IS WHAT HAPPENS TO THE SUN'S ENERGY WHEN
WE USE SOLAR CELLS TO GENERATE ELECTRICITY:
SOURCE | LOSS - % | POWER - W/m2 | |
---|---|---|---|
1. | solar constant | -- | 1370W |
2. | atmosphere | 27 | 1000W |
3. | clouds | 21 | 790W |
4. | sun angle1 | 49 | 403W |
5. | night2 | 50 | 201W |
6. | cell efficiency3 | 85 | 30W |
7. | dust/reflection4 | 10 | 27W |
8. | packaging5 | 20 | 22W |
9. | DC to AC inverter | 25 | 16W |
10. | storage | 30 | 11W |
Source Notes: 1. Calculated for both hour angle and a latitude angle of 37º. 2. See link. Continental U.S. average sunshine is 4.8 kilowatt-hours/ square meter/day, or 200 watts/square meter. That value is nearly identical with total losses shown for items 1-5 above. 3. See table on linked page. 4. Dust, bird droppings, scratches, etc. estimated to be about 4%. Reflections, per Fresnel's Law, would be another 6%. 5. See link for data sheet on typical solar panel. Data shows an overall efficiency of 10.3%, at nominal conditions. This is nearly identical with total losses shown for items 6-8 above. |
Net efficiency = 11.4 Watts/m2 or a mere 0.83% (!)
But read on, it gets worse.
Here is an example:
Siemens Solar (now Shell Solar) produces a popular line of large solar arrays intended for commercial, industrial and consumer applications. A big seller is their SP-150, supposedly a 150 watt unit that measures 1.32 square meters. The problem is, it only produces 150 watts under carefully controlled laboratory conditions where the incident light intensity is boosted to 1000 watts per square meter (unrealistically high, see items 2 and 3 in above table) and the PV cells are artificially cooled to 25º C. But when Shell tests that same unit under more realistic conditions of 800 watts per square meter and little cooling for the PV cells, the output drops to 109 watts. When sun angle and night time are factored in (see items 4 and 5 in above table), the average level of power production drops to a piddling 28 watts. (That is only 21 watts per square meter(!) which is nearly identical to the value shown for item 8 in the above table.) [+] [+]
In quantity, this unit sells for $700. That calculates out to $25 per watt. By way of comparison, the initial capitalization cost for a conventional power plant is on the order of $0.75 to $1.00 per watt. That makes the solar "alternative" 33 times more expensive than the conventional power plants of today, and we haven't even figured in the additional cost of the inverters and power storage systems that solar needs (or the land acquisition costs).
Solar proponents would be quick to point out that, while the capitalization costs may be higher for solar, they don't need to purchase the expensive fossil fuels that conventional plants use. While that is true, what they aren't telling you is that the cost of financing the much higher initial debt load for solar, is greater than the cost of the fuels that conventional plants use. (TANSTAAFL !)
Is there any use for solar power that makes sense?
Yes, solar power makes sense in those limited applications where the customer does not have convenient or economic access to the power grid, such as with remote country or mountain top homes. It is also useful for powering mobile or portable equipment such as utility, emergency, scientific devices, etc., where it is not otherwise feasible to hook to the power grid.
But other than those narrow exceptions, it makes no economic, engineering, ecological or practical sense to use solar power as a replacement for, or even as a compliment to, conventional power plants. Solar may have its' own specialty niche, but in no way does that rise to the level of an "alternative" to conventional power plants.
This person bought 4 55 watt panels for a thousand bucks. They have been in boxes in his garage for 3 or 4 years because he doesn't want to cut down the trees necessary to get the sun to the panels. He keeps talking about buying a Bergey windmill too.
He almost cried when I told him this country uses 3 quads per year which amounts to about 10 mwhr per person per year.
That would be more of a secondary premise, my primary point was that, as of today, solar power makes no economic, engineering, ecological or practical sense whatsoever.
But nevertheless, that was a pretty good summary and I enjoyed the reasoned exchange.
--Boot Hill
there are undoubtably quite few people who do not have the background in physics to understand the mechanics behind solar power. I guess Liberal is the word you use to describe the portion of that population who think solar energy is viable. Maybe its not, but honestly you have to realize any fanatisizm, or at least most of it, stems from a concern that is very natural. I dont know, I have read so much about Peak oil recently, that I wouldnt mind if more research went into alternative fuel sources. You may not agree, but understanding and accepting where other people are comming from will help build trust, and better conversation.....I don't know, you didn't say anything real offensive...but you know what i mean....
Amen!
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