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228 comments on DrumBeat: March 10, 2008

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tstreet on March 10, 2008 - 9:57am Permalink | Subthread | Parent | Comments top

Interesting comment about the reduced cooling requirements. In computing solar output, I guess solar companies should start talking about imputed output as well, from the cooling effect. On the other hand, what would the effect on heating be on sunny days in the winter.

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jokuhl on March 10, 2008 - 10:49am Permalink | Subthread | Parent | Comments top

This is worth considering, and has a number of useful combinations that can make Lemonade out of this in either seasonal extreme.

Here in a Colder climate (Coastal Maine), the shade on my roof ought to have barely a marginal effect on my 'Well-insulated' Attic, while the sun originally hitting that rooftop better NOT be considered some piece of my Passive Solar Heating Scheme, since surely some 95% or more of the heat of Sun hitting shingles is reflected or blown away, and never gets inside. In addition, the colder air keeps the PV functioning at a higher efficiency than a "hot" panel in warmer climes.

In Hot Climates, (perhaps all), it could be useful to Water Cool the panels, and let that be a preheating stage for your domestic Hot Water or Other Heating Needs. If PV gets to the point of being a Status symbol, I've even advocated putting 'Dummy' Panels up on one's Phoenix rooftops (my father-in-law, anyway), and get the benefit of the shade, plus the Cache'!

I'm eager to cover my rooftop with PV and Heating Panels of one sort or another, to keep these shingles young and fresh, and keep my attic from 'sweltering up' every summer. The Hot air panels that oftentimes have to get covered in the summertime, I have considered keeping active and ducting them to the Dryer, switching off the heater coils.. and to a Food Dehydration center in the basement. (I know, I know, clotheslines, yada, yada.. but we have very little, not too sunny- yard space, and the passage from Washer to yard is a challenge)

Antidoomer.. you got good discussion started today. Good work!

Bob

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DickLawrence on March 10, 2008 - 1:38pm Permalink | Subthread | Parent | Comments top

New solar-panel technology coming later this year will combine a solar PV panel with thin-plate back panel with fluid channels that absorbs most of the thermal energy of the PV cells (which isn't converted to electricity). With a single installation, there's kilowatts of electrical power to net-zero the electric bill, and all the hot water the family needs. This has the additional advantage of cooling the PV silicon so it's about 10% more efficient - that is, a typical Sharp, Sanyo, or Evergreen panel goes from 15% to about 16.5% efficient.

If you're interested in this, send me private email or look me up at the American Solar Energy conference & trade show in San Diego 5-8 May.

Dick Lawrence
ASPO-USA
dlawrence2 (at) gmail (dot) com

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theantidoomer on March 10, 2008 - 1:50pm Permalink | Subthread | Parent | Comments top

Sounds interesting and exciting Dick. Can you post a link concerning this technology?

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Cherenkov on March 10, 2008 - 2:44pm Permalink | Subthread | Parent | Comments top

http://www.energybulletin.net/40936.html

Potential Limits to Solar Cell Manufacture

Solar power is all the rage2 in the energy markets because of the thin film revolution, which promises low-cost mass production of photovoltaic (PV) cells (Technology Review, July 27, 2007). Leading the way is First Solar, which uses cadmium-telluride thin-film PVs in its solar panels. Scientific American's solar "grand plan" cites cadmium telluride as the cheapest option today.

To provide electricity at six cents per kWh by 2020, cadmium telluride modules would have to convert electricity with 14 percent efficiency, and systems would have to be installed at $1.20 per watt of capacity. Current modules have 10 percent efficiency and an installed system cost of about $4 per watt. Progress is clearly needed, but the technology is advancing quickly; commercial efficiencies have risen from 9 to 10 percent in the past 12 months...

First Solar has its detractors, who "assert that the company could be hurt by limited supplies of raw materials in the future and increased competition." It turns out that tellurium is one of the nine rarest elements on Earth. Here's the smoking gun from altenergystocks.com—

In 2006, First Solar's 60 megawatts of production consumed 4% of the world's annual supply of [tellurium]. In 2008, analysts expect revenues of approximately 4x the 2006 number, meaning they will need approximately 16% of new annual Tellurium supplies.

60 megawatts is nothing, a drop in the bucket. So much for cadmium-telluride thin film. But what of the many other alternatives?

For four years now, purified silicon has been in short supply. See the Wall Street Journal's The Silicon Shake-Up (subscriber only, September 21, 2007). Polysilicon prices soared from $25/kilogram in 2004 to around $200/kilogram in 2006, and PV production growth has come to a virtual halt. Sharp, the largest solar cell manufacturer in the world, "produced panels that could generate 434 megawatts of electricity [in 2006], or the equivalent of a single gas-fired power plant, about the same amount it made in 2005." The shortage has spurred the thin film craze because investors are leery of the polysilicon supply & demand imbalance, even though thin film PVs are only 7-10% efficient in converting sunlight, as opposed to about 15% for commercial silicon PVs.

In the case of depletion, as with cadmium telluride, the optimist might also respond that there are other alternatives, such as the copper-indium-(gallium)-diselenide (CIS or CIGS) thin film technology being pursued by Siemens, Nanosolar or Global Solar Energy. The risk is that the current bullish commodities market may become a permanent feature of the economic landscape. Take the indium used in thin films. Resource Investor reports that—

The Earth is estimated to contain about 0.1 ppm [parts per million] of indium which means it is about as abundant as silver. However, bullish supply-demand fundamentals have propelled the price from US$70/kg in 2001 to over US$1,000/kg today.

Indium is produced mainly from residues generated during zinc ore processing but is also found in iron, lead, and copper ores. In recent years, supply has decreased after a number of Chinese mining concerns stopped extracting indium from their zinc tailings.

At present, about 75% of the indium in the world is used in the manufacture of Liquid Crystal Displays (LCD’s), in computer screens and the new generation of flat screen TVs. The LCD industry is expected to achieve growth rates exceeding 30% over the next three years.

Looks like the solar cell industry will not be efficient for the campaign to...........

SAVE THE AUTOMOBILE!!!

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theantidoomer on March 10, 2008 - 3:24pm Permalink | Subthread | Parent | Comments top

Wow, Cherenkov, thanks for not providing something helpful on my question and posting a unrelated answer, thanks! Anywho, here's a article on how indium could be replace by carbon nanotubes.

http://www.eetimes.com/showArticle.jhtml?articleID=201201762

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jokuhl on March 10, 2008 - 4:53pm Permalink | Subthread | Parent | Comments top

Antidoomer;
To be fair, what Cherenkov just did, pulling a grand (in this case negative) conclusion from a single article, as if that said it all, is the same tactic that a number of your posts get so attacked for. I think there's an implication in them that says 'So there. Here's an alleged solution. What energy problem?' Even if that's not really your intention, it is the subtext that I sense from them again and again, and it doesn't usually offer much beyond a sort of Adamant Triumphalism, as opposed to simply hopefulness.

Respectfully,
Bob

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BrianT on March 10, 2008 - 6:12pm Permalink | Subthread | Parent | Comments top

Anti: All this talk about the GIANT solar power industry. The solar power industry is a shrimp predicted to be a giant. This shrimp has been predicted to be a giant for quite a while now. Cherenkov was making a good point-a shrimp growing quickly does not a giant make.

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jokuhl on March 10, 2008 - 8:26pm Permalink | Subthread | Parent | Comments top

Cherenkov is happy any time he can howl about Cars being evil.

I generally find Alan Drake's way of putting it much more convincing and productive, which is to say that Electric rail and Bikes make more sense than EVs. Adding a lot of exclamation marks and bold-type makes cherenkov's arguments weaker, not stronger. Misspent Energy, if you will.

Bob

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Squalish on March 10, 2008 - 5:12pm Permalink | Subthread | Parent | Comments top

As far as potential limits to solar cell manufacture, I found this report: Future State of the PV Industry - Trends and Technologies to be instructive.

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alan on March 11, 2008 - 2:13pm Permalink | Subthread | Parent | Comments top

First Solar has its detractors, who "assert that the company could be hurt by limited supplies of raw materials in the future and increased competition."

There may not be enough tellurium to cover all our rooftops with solar panels made from them but I'm sure there is enough for First Solar while we attempt it.

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Black_Dog on March 10, 2008 - 2:30pm Permalink | Subthread | Parent | Comments top

Sounds like a great idea, but likely isn't. Given that one needs 2 (that's two) layers of glass for minimal thermal insulation, the PV output will be reduced about 8% for each extra layer. Also, is the PV layer going to exhibit different spectral characteristics in the infrared (reflecting) vs. the visible (absorbing)? Otherwise, the infrared emissions will reduce the efficiency of the thermal collection side of the efficiency equation.

I saw a posting last week about a system using air cooling, without any insulating cover plates. That one looked like a complete waste of effort to me, since the thermal efficiency would go to zero when the ambient temperature was low. The result, no hot water in winter.

E. Swanson

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