California schools $120M solar project
in [Design]
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From: wmbjkREMOVE on 2 Jun 2010 11:35 On Wed, 2 Jun 2010 09:38:28 +0100, Ahem A Rivet's Shot <steveo(a)eircom.net> wrote: >On Tue, 01 Jun 2010 17:18:57 -0700 >wmbjkREMOVE(a)citlink.net wrote: > >> On Tue, 1 Jun 2010 23:56:08 +0000 (UTC), don(a)manx.misty.com (Don >> Klipstein) wrote: >> >> >> > Compare that to the 1 KW >> >per square meter that I have some impression that solar cell arrays are >> >rated at... >> >> Where'd you get that impression? Here's a typical module. > > Probably from reading the specs and knowing about the typical >efficiency of PV cells. The output rating of PV cells is usually quoted >under "full sun" conditions of around 1000 W per sq. metre. > >> http://sunelec.com/index.php?main_page=product_info&cPath=5&products_id=807. >> ~135W per sq. meter. > > That's the electrical output of that panel, No kidding? > which given the normal >efficiency of panels like that (10-15%) means an insolation of around 1000 W >per sq. meter. Actually the specs for that panel claim 13.1% efficiency so >slightly over 1000 W per sq. metre is required to achieve that output. > >> > That sounds to me like 34-47 dollars per watt in Philadelphia, if the >> >panels are laid horizontally. >> >> GIGO > > Not so - those were pretty accurate calculations. If Klipstein mounts one of the modules I referenced above in full sun in Philly on a cool day and measures the output, he'll conclude that it costs out at ~$2 per Watt, not the $30-$40 he managed to arrive at. To avoid starting with worst case PV costs he could google "best price PV". And he could skip even more GIGO by using HOMER or some such. http://homerenergy.com/ Which would prevent erroneous assumptions such as his 5% of production for tracking. Seriously? Try ~20Whrs per day, which on a 1000W array in Philly might net out to ~.5% minus for the motor, but >20% plus overall. PV economics aren't great, especially if one is willing to ignore the unbilled-cost of grid energy and the unsustainability of the billed cost. So those who seek to be negative about the economics really don't need to exaggerate. Wayne
From: Martin Brown on 2 Jun 2010 12:01 On 02/06/2010 16:35, wmbjkREMOVE(a)citlink.net wrote: > On Wed, 2 Jun 2010 09:38:28 +0100, Ahem A Rivet's Shot > <steveo(a)eircom.net> wrote: > >> On Tue, 01 Jun 2010 17:18:57 -0700 >> wmbjkREMOVE(a)citlink.net wrote: >> >>> On Tue, 1 Jun 2010 23:56:08 +0000 (UTC), don(a)manx.misty.com (Don >>> Klipstein) wrote: >>> >>> >>>> Compare that to the 1 KW >>>> per square meter that I have some impression that solar cell arrays are >>>> rated at... >>> >>> Where'd you get that impression? Here's a typical module. >> >> Probably from reading the specs and knowing about the typical >> efficiency of PV cells. The output rating of PV cells is usually quoted >> under "full sun" conditions of around 1000 W per sq. metre. >> >>> http://sunelec.com/index.php?main_page=product_info&cPath=5&products_id=807. >>> ~135W per sq. meter. >> >> That's the electrical output of that panel, > > No kidding? > >> which given the normal >> efficiency of panels like that (10-15%) means an insolation of around 1000 W >> per sq. meter. Actually the specs for that panel claim 13.1% efficiency so >> slightly over 1000 W per sq. metre is required to achieve that output. >> >>>> That sounds to me like 34-47 dollars per watt in Philadelphia, if the >>>> panels are laid horizontally. >>> >>> GIGO >> >> Not so - those were pretty accurate calculations. > > If Klipstein mounts one of the modules I referenced above in full sun > in Philly on a cool day and measures the output, he'll conclude that > it costs out at ~$2 per Watt, not the $30-$40 he managed to arrive at. That is their price per peak output per watt installed and seems unusually low. $4/W is still about the going rate and some are closer to $8/W where you paying a premium for higher efficiency. But unless you can arrange continuous sunlight the average output over the year allowing for clouds and including diffuse light is something like 1/8 to 1/10 of peak installed capacity. So his $30-40/W delivered for use is basically in the right ballpark in the long term. Operating at peak efficiency with a clear sky and normal incidence sunlight then the array can achieve peak performance, but the rest of the time it does not by a long way. And obviously at night it is idle. > motor, but>20% plus overall. PV economics aren't great, especially if > one is willing to ignore the unbilled-cost of grid energy and the > unsustainability of the billed cost. So those who seek to be negative > about the economics really don't need to exaggerate. I think you just have to be clear about what measure you are using. The PV array link you pointed at is the cheapest I have seen on offer - has anyone here obtained one? Or are they vapourware? Regards, Martin Brown
From: Ahem A Rivet's Shot on 2 Jun 2010 12:45 On Wed, 02 Jun 2010 17:01:29 +0100 Martin Brown <|||newspam|||@nezumi.demon.co.uk> wrote: > The PV array link you pointed at is the cheapest I have seen on offer - > has anyone here obtained one? Or are they vapourware? The string ribbon process mentioned appears to belong to Evergreen Solar, it looks to be a very clever process for producing silicon PV cells. -- Steve O'Hara-Smith | Directable Mirror Arrays C:>WIN | A better way to focus the sun The computer obeys and wins. | licences available see You lose and Bill collects. | http://www.sohara.org/
From: Paul Keinanen on 2 Jun 2010 16:11 On Wed, 02 Jun 2010 08:35:00 -0700, wmbjkREMOVE(a)citlink.net wrote: > >If Klipstein mounts one of the modules I referenced above in full sun >in Philly on a cool day and measures the output, he'll conclude that >it costs out at ~$2 per Watt, not the $30-$40 he managed to arrive at. Unfortunately the Earth does not constantly turn the same face against the sun. In places close to th equator with only rare clouds (such as Sahara) with dual axis tracker, in principle the nominal power would be avaible 50 % of the time, thus the average cost would be $4/W. However, the air mass losses close to the horizon will limit the full power time to 8-10 hours a day, thus at least $5/W in ideal cases. For fixed installations in ideal cases 1/4 of the peak power would be available on average (hence $8/W) . For higher latitudes, the winter atmospheric losses will reduce the available power significantly, even with ideal orientation. In many places, there are those pesky things called clouds .... This will further reduce the annual energy output and hence increase the cost/W. >To avoid starting with worst case PV costs he could google "best price >PV". And he could skip even more GIGO by using HOMER or some such. >http://homerenergy.com/ Which would prevent erroneous assumptions such >as his 5% of production for tracking. While 5 % may be a lot, but on the other hand, can you buy a system with a solar panel mounted on a dual tracker capable of surviving snow/ice/sand storm/hurricanes for $2/W (peak) ?
From: Michael on 2 Jun 2010 17:43
On Jun 1, 2:53 pm, "Michael A. Terrell" <mike.terr...(a)earthlink.net> wrote: > z wrote: > > > "Michael A. Terrell" <mike.terr...(a)earthlink.net> wrote in > >news:YcKdnVzaNLRnrJjRnZ2dnUVZ_qKdnZ2d(a)earthlink.com: > > > > vaughn wrote: > > > >> "Sylvia Else" <syl...(a)not.here.invalid> wrote in message > > >>news:86j7pjF9i7U1(a)mid.individual.net... > > > >> > I don't believe in these alleged economies of scale. Solar panels > > >> > already represent a large industry. The economies of scale, such as > > >> > they are, have already been obtained. > > > >> Not so, especially not so at the consumer level. At the consumer > > >> level PV panels remain a nitch product, so lack of retail competition > > >> and huge shipping costs because of a lack of any local distribution > > >> channel presents significant barriers. > > > >> Vaughn > > > > Harbor Freight sells several panels & systems. They do mail order > > > and > > > have a lot of retail stores in the US. > > > > <http://www.harborfreight.com/catalogsearch/result/index/?category=&q=s > > > olar&limit=32> > > > OUCH! the larger panels there are 6-8 dollars a watt > > And no shipping if you buy them at a local store. Right... the store pays the shipping and passes the cost right on to the customer. :D Michael D. |