The best heat transfer pastes for processors has silver in it and I belive silver is conductive.
Logan Vilas ----- Original Message ----- From: "Jason & Katie" <[EMAIL PROTECTED]> To: <Biofuel@sustainablelists.org> Sent: Monday, May 15, 2006 7:02 PM Subject: Re: [Biofuel] Solar Concentrator & PV Modules > aha, this is where i find a new idea. > > the dielectric heat grease used between processors and heat sinks /should/ > work to electrically insulate the cell from the water pack (not jackets, a > flat sleeve covering the back with circulated coolant completely filling > it) > while conducting heat into the cooling vanes in the water pack, > eliminating > the risk of breakage, just as you say. the goop isnt exactly cheap, but it > works rather effectively on high temp applications. > > ----- Original Message ----- > From: "Joe Street" <[EMAIL PROTECTED]> > To: <Biofuel@sustainablelists.org> > Sent: Monday, May 15, 2006 9:26 AM > Subject: Re: [Biofuel] Solar Concentrator & PV Modules > > >> Silicon is quite fragile especially the thin polysilicon material used >> in cells. You are right but any water pressure would break the cells. >> You need to bond them onto a heat conducting back plate like copper or >> aluminum with a heat conducting cement. Aso the back is an electrical >> contact so you need isolation there. >> >> Joe >> >> Jason & Katie wrote: >> >>> in theory, if one could find a way to waterproof the back of a PV cell >>> it >>> could be used as the heat-side plate in this concentrator/boiler found >>> at >>> (or after) http://www.ida.net/users/tetonsl/solar/page_46.htm you could >>> safely increase the power range of a smaller PV cell without too >>> horrible >>> of >>> a heat loss. the problem is finding a sealing substance that wont melt >>> or >>> burn under these 1200*F temperatures. >>> >>> >>> ----- Original Message ----- >>> From: "logan vilas" <[EMAIL PROTECTED]> >>> To: <Biofuel@sustainablelists.org> >>> Sent: Friday, May 12, 2006 4:54 PM >>> Subject: Re: [Biofuel] Solar Concentrator & PV Modules >>> >>> >>> >>>>I am working with the idea of building my own Concentrator with about 50 >>>>times the mirror space then collector space. That Is why the question >>>>was >>>>asked in the first place I was wondering if placeing a 50watt solar >>>>panel >>>>at >>>>the focal point would increase the power output. I've read that it is >>>>more >>>>then 100% liner increase in power output when increasing the amount of >>>>light >>>>on it. a normal panel at 50 watts would be 2500 watts at 50 suns. I know >>>>it >>>>would need to be kept cool. due to the fact that they are only 20-30% >>>>efficent, but I could use the coolant to heat my biodiesel processor, >>>>then >>>>the hot water going into my home before a tankless heater. If I were to >>>>get >>>>a grid tied inverter It would suppliment my normal power useage and maby >>>>with netmetering it might come close to canceling out my power >>>>requirements >>>>alltogther. a simple temp sensor could be used so if the temp is over >>>>150f >>>>in the coolant it will shut down and not collect the sun anymore. As for >>>>a >>>>solar tracker that is relative easy with very simple electronics. The >>>>setup >>>>to hold everything would be a simple build for most people who can make >>>>their own biodiesel processor. And If I base it off a 7 meter dish I can >>>>get >>>>those free. I just have to use the labor to remove it. >>>> >>>>Logan Vilas >>>>----- Original Message ----- >>>>From: "Zeke Yewdall" <[EMAIL PROTECTED]> >>>>To: <Biofuel@sustainablelists.org> >>>>Sent: Friday, May 12, 2006 3:59 PM >>>>Subject: Re: [Biofuel] Solar Concentrator & PV Modules >>>> >>>> >>>> >>>>>I am speaking mostly from experience, from what I have seen work and >>>>>fail in the field, and what I can buy to install for my clients. The >>>>>reason I talk about trackers on large poles is because that is what is >>>>>commercially sold right now (at least in the US, europe is ahead of us >>>>>in many areas). And the biggest reason I see for failed systems is >>>>>lack of maintenance (mostly batteries, but also anything that moves). >>>>>Also, the number of new innovative PV systems that I have seen come on >>>>>the market over the years, only to dissapear within another year... >>>>>We're still basically doing the same thing as PV was in the 70's, with >>>>>incremental improvements in efficiency and incremental cost decreases. >>>>>I called the concrentrating PV exotic merely because I can't call up >>>>>one of 200 some suppliers and buy one that meets all current >>>>>electrical code, whereas I can with silicon PV modules. Maybe another >>>>>breakthrough is coming, but in the mean time, alot of people will keep >>>>>using coal generated power because they are waiting for those >>>>>breakthroughs. I would rather see working PV systems going in today, >>>>>even if they aren't all that high tech, rather than people thinking >>>>>they have to wait before solar energy can work for them -- and in the >>>>>mean time continuing to support coal and oil. It's not that I want >>>>>to limit the new technology, but what I have seen is that the >>>>>layperson holds out the possibility of a paradigm shift in the >>>>>technology in the future as a reason to do absolutely nothing now. >>>>>And if I recall, the original question was about concentrating >>>>>sunlight on a normal old PV module -- which isn't the best idea -- >>>>>they tried that at the carrizo solar plant in the early 80's, and a >>>>>few years later, a whole lot of used Mud-lams (because the encapsulant >>>>>turned varying shades of brown) flooded the market for off-grid use. >>>>> >>>>>I do admit that this list's members are not your average layperson, >>>>>and most of us won't just use the news of new inventions as an excuse >>>>>for procrastinating, so I apologize for that. >>>>> >>>>>Zeke >>>>> >>>>> >>>>>On 5/12/06, Michael Redler <[EMAIL PROTECTED]> wrote: >>>>> >>>>>>By now, you may have noticed my resistance to "conventional wisdom" >>>>>>whenever >>>>>>someone gives negative feedback about a particular energy scheme. Here >>>>>>is >>>>>>an >>>>>>example. >>>>>> >>>>>>The idea of concentrating light onto PV cells is a relatively new idea >>>>>>in >>>>>>some circles. What to do about waste heat is a natural progression in >>>>>>the >>>>>>discussion of such technology. But, why is it seen as such an >>>>>>obstacle - >>>>>>especially when schemes for harvesting waste heat are so abundant in >>>>>>energy >>>>>>related discussions? >>>>>> >>>>>>You wrote: "...regular PV is cheap enough that the simplicity of not >>>>>>having >>>>>> >>>>>>moving parts will probably outweigh any advantage of trying to get >>>>>>more >>>>>>from >>>>>>the same amount of silicon." >>>>>> >>>>>> >>>>>>The sweeping statements are getting old Zeke. Adding trackers become >>>>>>advantageous when you run out of roof. By the way PV that works on >>>>>>concentrated sunlight isn't so exotic and will probably become the PV >>>>>>of >>>>>>choice in a large percentage of applications. The large cost of >>>>>>concentrating PV is likely to be offset by an increase in power >>>>>>conversion >>>>>>requiring the use of heliostats, tracking technology and those pesky >>>>>>moving >>>>>>parts. >>>>>> >>>>>> >>>>>>Mike >>>>>> >>>>>>Zeke Yewdall <[EMAIL PROTECTED]> wrote: >>>>>> >>>>>>Most of the highest efficiency PV cells do use concentrators. These >>>>>>are the 35% efficient super exotic ones that NREL and others are >>>>>>working on. Compared to 20% which is about the highest commercial >>>>>>single sun efficiency right now. In general the power produced by a >>>>>>PV cell is linearly related to the energy input. More sun = more >>>>>>power. So if you put 25 suns on it, you get 25 times the amount of >>>>>>power from the same cell (assuming you don't change the spectral >>>>>>composition of the l ight). It's not quite linear, so I think you >>>>>>actually get a tiny bit more power at higher concentrations than just >>>>>>the concentration ratio would imply -- say 28 instead of 25. The >>>>>>problem is that a typical crystalline silicon cell also decreased its >>>>>>power about 0.5% for each degree celsius the temperature goes up. So >>>>>>if you increase the operating temperature of the cell from 60C >>>>>>(typical for one sun) to 200C, you've just lost all the power you >>>>>>gained by putting more light on it.... Plus if you get too hot, >>>>>>you'll damage it -- usually the encapsulating material degrades well >>>>>>before the temperature at which the actual PV cell is damaged though. >>>>>>The other thing is that concentrators require tracking the sun usually >>>>>>(at least to achieve more than 2 or 3 times concentration. This >>>>>>introduces moving parts to the equation, and destroys one of the nice >>>>>>features of PV. If it's a big central power station where you can >>>>>>hire a full time maintenance operator, then go ahead. If for your own >>>>>>house, regular PV is cheap enough that the simplicity of not having >>>>>>moving parts will probably outweigh any advantage of trying to get >>>>>>more from the same amount of silicon. >>>>>> >>>>>>Zeke >>>>>> >>>>>>On 5/12/06, Joe Street wrote: >>>>>> >>>>>>>Actually mirrors can be used to concentrate the light from a large >>>>>>>area >>>>>>>onto a small high efficiency solar cell. It is being done. This is >>>>>>>one >>>>>>>of the justifications for the cost of high efficiency cells but the >>>>>>>extra cost of the concentrators and the lengths one has to go to to >>>>>>>keep >>>>>>>from overheating the PV module unfortunately outstrip the savings the >>>>>>>idea hopes to offer. Too bad but on the other hand if you are just >>>>>>>fortunate to have access to heterojunction cells on the cheap then >>>>>>>maybe >>>>>>>you should go for it! You will need a liquid cooled backing plate for >>>>>>>the cells but if you are crafty you might be able to use the rejected >>>>>>>heat somehow as well! >>>>>>> >>>>>>>Joe >>>>>>> >>>>>>>Lugano Wilson wrote: >>>>>>> >>>>>>> >>>>>>>>hi Logan. >>>>>>>> >>>>>>>>PV modules and solar concentrators are two different technologies >>>>>>>>and >>>>>>>>unfortunately, their individual energy capture principle is >>>>>>>>contradicting to each other. consequently, they can not be used at >>>>>>>>same >>>>>>>>application. PV modules need to absorb all the solar radiation so as >>>>>>>>to >>>>>>>>generate electricity through the module cells where as solar >>>>>>>>concentrators have to reflect all the solar radiation and direct it >>>>>>>>at a >>>>>>>>specific location (ie concentrated) for the purpose of heating a >>>>>>>>medium >>>>>>>>that can latter generate required energy. you therefore need to >>>>>>>>choose >>>>>>>>one for a specific application. however, when it comes to >>>>>>>>electricity >>>>>>>>the pv modules are good due to the fact that you can size them >>>>>>>>depending >>>>>>>>on your requirement starting with one module and increasing. >>>>>>>>concentrators for electricity is a large scale project - not so >>>>>> >>>>>>"modular". >>>>>> >>>>>>>>Lugano >>>>>>>> >>>>>>>>*/Logan Vilas /* wrote: >>>>>>>> >>>>>>>>Would a standard PV module produce more when used with a Solar >>>>>>>>Concentrator >>>>>>>>or does it require a special PV module? >>>>>>>> >>>>>>>>Logan Vilas >>>>>> >>>>>>[snip] >>>>>>_______________________________________________ >>>>>>Biofuel mailing list >>>>>>Biofuel@sustainablelists.org >>>>>>http://sustainablelists.org/mailman/listinfo/biofuel_sustainablelists.org >>>>>> >>>>>>Biofuel at Journey to Forever: >>>>>>http://journeytoforever.org/biofuel.html >>>>>> >>>>>>Search the combined Biofuel and Biofuels-biz list archives (50,000 >>>>>>messages): >>>>>>http://www.mail-archive.com/biofuel@sustainablelists.org/ >>>>>> >>>>>> >>>>>> >>>>>> >>>>> >>>>>_______________________________________________ >>>>>Biofuel mailing list >>>>>Biofuel@sustainablelists.org >>>>>http://sustainablelists.org/mailman/listinfo/biofuel_sustainablelists.org >>>>> >>>>>Biofuel at Journey to Forever: >>>>>http://journeytoforever.org/biofuel.html >>>>> >>>>>Search the combined Biofuel and Biofuels-biz list archives (50,000 >>>>>messages): >>>>>http://www.mail-archive.com/biofuel@sustainablelists.org/ >>>>> >>>>> >>>> >>>> >>>>_______________________________________________ >>>>Biofuel mailing list >>>>Biofuel@sustainablelists.org >>>>http://sustainablelists.org/mailman/listinfo/biofuel_sustainablelists.org >>>> >>>>Biofuel at Journey to Forever: >>>>http://journeytoforever.org/biofuel.html >>>> >>>>Search the combined Biofuel and Biofuels-biz list archives (50,000 >>>>messages): >>>>http://www.mail-archive.com/biofuel@sustainablelists.org/ >>>> >>>> >>>>-- >>>>No virus found in this incoming message. >>>>Checked by AVG Free Edition. >>>>Version: 7.1.385 / Virus Database: 268.5.6/338 - Release Date: 5/12/2006 >>>> >>>> >>> >>> >>> >>> _______________________________________________ >>> Biofuel mailing list >>> Biofuel@sustainablelists.org >>> http://sustainablelists.org/mailman/listinfo/biofuel_sustainablelists.org >>> >>> Biofuel at Journey to Forever: >>> http://journeytoforever.org/biofuel.html >>> >>> Search the combined Biofuel and Biofuels-biz list archives (50,000 >>> messages): >>> http://www.mail-archive.com/biofuel@sustainablelists.org/ >>> >>> >> >> >> _______________________________________________ >> Biofuel mailing list >> Biofuel@sustainablelists.org >> http://sustainablelists.org/mailman/listinfo/biofuel_sustainablelists.org >> >> Biofuel at Journey to Forever: >> http://journeytoforever.org/biofuel.html >> >> Search the combined Biofuel and Biofuels-biz list archives (50,000 >> messages): >> http://www.mail-archive.com/biofuel@sustainablelists.org/ >> >> >> -- >> No virus found in this incoming message. >> Checked by AVG Free Edition. >> Version: 7.1.385 / Virus Database: 268.5.6/338 - Release Date: 5/12/2006 >> >> > > > _______________________________________________ > Biofuel mailing list > Biofuel@sustainablelists.org > http://sustainablelists.org/mailman/listinfo/biofuel_sustainablelists.org > > Biofuel at Journey to Forever: > http://journeytoforever.org/biofuel.html > > Search the combined Biofuel and Biofuels-biz list archives (50,000 > messages): > http://www.mail-archive.com/biofuel@sustainablelists.org/ > > _______________________________________________ Biofuel mailing list Biofuel@sustainablelists.org http://sustainablelists.org/mailman/listinfo/biofuel_sustainablelists.org Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Search the combined Biofuel and Biofuels-biz list archives (50,000 messages): http://www.mail-archive.com/biofuel@sustainablelists.org/
