by Devil » Thu 30 Jun 2005, 06:03:09
$this->bbcode_second_pass_quote('jeffvail', 'D')evil,
www.gaiam.com lists a 165 Watt PV panel at $940. Not quite $200 for 150 Watts. And that's with government subsidies, and not counting the very expensive (and short lived) batteries, the intertie, etc.
But let's assume your figure of $200 for 150 watt panel, and let's assume that it will last 30 years:
The total energy required to produce a product can be considered equal to its price, as the concept of oportunity cost translates equally across energy, labor, and all other economic inputs. So, being generous and assuming a $60 barrel of oil (even though the recent price rises have yet to be incorporated into retail prices), one $200, 150W PV panel requires 3.33 barrels of crude to produce. 3.3 barrels of crude is equivalent to 5.6 MWH, which is just over half what you predict your panel will generate in 30 years. If you use actual panel prices (as I mention above, which is 4.3 times as expensive as your example), then a $940 165 W Panel only generates 45% of the energy required to produce it over 30 years. Either way, it's a very poor return on a 30-year investment.
So in simpler terms:
With $940 you can buy either one 165W panel or 15 barrels of crude oil. Over 30 years, you'll get 45% as much energy out of the panel as you will get right now out of the crude.The EROEI on PV Solar is terrible -- it's critical to remember to calculate not just the energy used in the PV panel manufacturing plant, but ALL the energy used in the entire production chain: energy to power the mining equipment, the ore processing equipment, the transportation of the raw materials, the transporation of the finished product, the energy required to feed, cloth & house the workers, etc. Because if you cut that part out of the equation, no solar panel. EROEI = <1
~Jeff
I apologise: when I wrote that, I must have been running out of caffeine! I guess the 200 figure I had in mind must have been the local currency price less the subsidies! OK, the going price for 165 W is nearer the $700 mark RETAIL than the $940 you quote. There are many places on the web at the lower price, such as
http://www.partsonsale.com/solarex.html
Nevertheless, my argument is still valid. If it costs $5500 to make in electricity costs alone (assuming everything else is free), it could not be sold retail below about $10,000, not $700.
In fact, I cannot quote actual figures, but the costing breakdown has been published on this forum several times before. If my memory serves me correctly, the energy consumed in the holistic manufacture of solar panels is equivalent to about 3½ years of their electricity production. If you wish it more precisely, please do a search.
Of course, you make several assertions that are ridiculous, such as subsidies. How can you state that they are subsidised, when they are manufactured internationally (Japan, Russia, Switzerland, Germany, Netherlands, China etc.)? Do you really believe that each country is part of a price-fixing consortium that regulates subsidies accordingly??? Then your idea that the retail price of an object is equivalent to the energy used in making it; that is simply ludicrous. If I'm a PV retailer with a panel at $900 and I drop the price to $700 (still making a hefty profit, BTW) then the manufaturing energy has suddenly dropped from 15 barrels of crude to less than 12 bbl. And you can hardly compare retail prices to bulk commodity prices. You could not go to Exxon and say, "here's $60, please sell me a barrel of crude sweet". Apples and oranges.
The key is to min heat gain and loss (winter). I would think radiation barriers in the roof would help a lot. I saw a interesting study in FL about roof types. The more reflective the better. This could save a lot of energy in southern climates and it is fairly easy to retrofit existing buildings.
