Solar panel efficency
in [Design]
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From: Dirk Bruere at NeoPax on 9 Jun 2010 17:50 On 09/06/2010 21:29, Martin Brown wrote: > On 09/06/2010 20:54, Paul Keinanen wrote: >> On Wed, 09 Jun 2010 11:04:45 +0100, Martin Brown >> <|||newspam|||@nezumi.demon.co.uk> wrote: >> >>> On 05/06/2010 03:11, Sylvia Else wrote: >>>> On 5/06/2010 10:41 AM, Bill Bowden wrote: >> >>>>> How about hydro-electric which qualifies as renewable. Why waste time >>>>> with solar if economics are better with hydro? Or is this a dumb >>>>> question? >>>> >>>> The economics of hydro are good, if there's a suitably place to build >>>> one. Suitable means that the topography and rainfall have to be >>>> appropriate, and it's mustn't be too far from the place where the power >>>> will be used. >>> >>> Or you can be clever and use hydro pumped storage at two different >>> levels to supply fast peak demand and then run it backwards at night >>> when generation for base load is more than demand. The overall >>> efficiency is not that great, but the very fast start capability is >>> worthwhile for key aspects of load balancing. >> >> You must be really desperate, if you start thinking about pumping >> storage :-). > > It is faintly useful for transient load balancing - quick to come > onstream with full power and synchronisation in 12s from standby. And it > is probably better to use some pumped storage than smelt a bit more > iron, aluminium or make sodium and chlorine which are the ultimate load > balancing energy dumps on lowest rate very interuptable tariff. >> >> At low latitudes in which the annual peak load is in the summer, due >> to air conditioning, it is economically sensible to build solar (PV >> or solar thermal) plants with a total power as large as the day/night >> consumption difference. Building more than that will require desperate >> measures as pumping storage or accumulators. Check your local >> day/night consumption figures. > > And/or put them on the roof so that some solar power goes into PV cells > and the roof itself is not heated by direct sunlight. >> >> At higher latitudes (Central and Northern Europe), the peak >> consumption is during the winter months, with minimal solar >> production. During the summer months, when the solar production is >> high, the consumption is low (and nuclear power plants are shut down >> for annual maintenance during the summer) and hence the price that you >> can get from the solar electricity is quite low. > > I agree. PV is a dead loss at our latitude since it hardly generates > anything at all in the dull grey winters. To my amazement though in the > bleak midwinter on the few sunny days with blue skies my friends 2kW PV > array generates about 800W despite the low midday solar elevation of > just 26 degrees. The cold improves the overall efficiency somewhat - and > conversely a hot panel derates its output with extra losses. The > combined water heating and PV designs look like a smart idea if the > reliability can be improved. Esp using a small PV array to pump the water round the solar heater. No sunlight, less electricity, less water pumped -- Dirk http://www.transcendence.me.uk/ - Transcendence UK http://www.blogtalkradio.com/onetribe - Occult Talk Show
From: Paul Keinanen on 9 Jun 2010 17:58 On Wed, 09 Jun 2010 21:29:52 +0100, Martin Brown <|||newspam|||@nezumi.demon.co.uk> wrote: >On 09/06/2010 20:54, Paul Keinanen wrote: >> At higher latitudes (Central and Northern Europe), the peak >> consumption is during the winter months, with minimal solar >> production. During the summer months, when the solar production is >> high, the consumption is low (and nuclear power plants are shut down >> for annual maintenance during the summer) and hence the price that you >> can get from the solar electricity is quite low. > >I agree. PV is a dead loss at our latitude since it hardly generates >anything at all in the dull grey winters. To my amazement though in the >bleak midwinter on the few sunny days with blue skies my friends 2kW PV >array generates about 800W despite the low midday solar elevation of >just 26 degrees. Thus the zenith distance would be 64 degrees. At Christmas, the solar declination is -23.5 degrees, Thus, your friend must be living at 40.5 degrees latitude (Barcelona, Athens) latitude. In Spain, there are several solar thermal electric powerplants in the few megawatt class.
From: Mark on 10 Jun 2010 15:41 On Jun 9, 5:58 pm, Paul Keinanen <keina...(a)sci.fi> wrote: > On Wed, 09 Jun 2010 21:29:52 +0100, Martin Brown > > <|||newspam...(a)nezumi.demon.co.uk> wrote: > >On 09/06/2010 20:54, Paul Keinanen wrote: > >> At higher latitudes (Central and Northern Europe), the peak > >> consumption is during the winter months, with minimal solar > >> production. During the summer months, when the solar production is > >> high, the consumption is low (and nuclear power plants are shut down > >> for annual maintenance during the summer) and hence the price that you > >> can get from the solar electricity is quite low. > > >I agree. PV is a dead loss at our latitude since it hardly generates > >anything at all in the dull grey winters. To my amazement though in the > >bleak midwinter on the few sunny days with blue skies my friends 2kW PV > >array generates about 800W despite the low midday solar elevation of > >just 26 degrees. > > Thus the zenith distance would be 64 degrees. > > At Christmas, the solar declination is -23.5 degrees, > > Thus, your friend must be living at 40.5 degrees latitude (Barcelona, > Athens) latitude. > > In Spain, there are several solar thermal electric powerplants in the > few megawatt class. you will know when solar PV have "made it" (become economical) when you see the factory that makes them, has them on the roof and doesn't use much power from the grid.. Mark
From: Martin Brown on 10 Jun 2010 15:59 On 10/06/2010 20:41, Mark wrote: > On Jun 9, 5:58 pm, Paul Keinanen<keina...(a)sci.fi> wrote: >> On Wed, 09 Jun 2010 21:29:52 +0100, Martin Brown >> >> <|||newspam...(a)nezumi.demon.co.uk> wrote: >>> On 09/06/2010 20:54, Paul Keinanen wrote: >>>> At higher latitudes (Central and Northern Europe), the peak >>>> consumption is during the winter months, with minimal solar >>>> production. During the summer months, when the solar production is >>>> high, the consumption is low (and nuclear power plants are shut down >>>> for annual maintenance during the summer) and hence the price that you >>>> can get from the solar electricity is quite low. >> >>> I agree. PV is a dead loss at our latitude since it hardly generates >>> anything at all in the dull grey winters. To my amazement though in the >>> bleak midwinter on the few sunny days with blue skies my friends 2kW PV >>> array generates about 800W despite the low midday solar elevation of >>> just 26 degrees. >> >> Thus the zenith distance would be 64 degrees. >> >> At Christmas, the solar declination is -23.5 degrees, >> >> Thus, your friend must be living at 40.5 degrees latitude (Barcelona, >> Athens) latitude. >> >> In Spain, there are several solar thermal electric powerplants in the >> few megawatt class. > > you will know when solar PV have "made it" (become economical) when > you see the factory that makes them, has them on the roof and doesn't > use much power from the grid.. That is an excessive requirement. It becomes worthwhile when the total energy payback on solar is 10-100x that of manufacture. At the moment it is around 6-8x for PV and rising so there is hope for it yet. OTOH at my latitude where the sun barely makes 12 degrees above the horizon at midday in mid winter PV is pretty useless. The PV powered "warning bend - skid hazard" roadsigns tend to die a horrible death every winter if they are not totalled first by some speeding nutter. Kind of sad really - they work brilliantly all summer when there is no frost and lots of sunshine and as soon as winter comes they run out of battery power about an hour after sundown even on sunny days. Regard, Martin Brown
From: BlindBaby on 10 Jun 2010 16:07
On Thu, 10 Jun 2010 20:59:22 +0100, Martin Brown <|||newspam|||@nezumi.demon.co.uk> wrote: >On 10/06/2010 20:41, Mark wrote: >> On Jun 9, 5:58 pm, Paul Keinanen<keina...(a)sci.fi> wrote: >>> On Wed, 09 Jun 2010 21:29:52 +0100, Martin Brown >>> >>> <|||newspam...(a)nezumi.demon.co.uk> wrote: >>>> On 09/06/2010 20:54, Paul Keinanen wrote: >>>>> At higher latitudes (Central and Northern Europe), the peak >>>>> consumption is during the winter months, with minimal solar >>>>> production. During the summer months, when the solar production is >>>>> high, the consumption is low (and nuclear power plants are shut down >>>>> for annual maintenance during the summer) and hence the price that you >>>>> can get from the solar electricity is quite low. >>> >>>> I agree. PV is a dead loss at our latitude since it hardly generates >>>> anything at all in the dull grey winters. To my amazement though in the >>>> bleak midwinter on the few sunny days with blue skies my friends 2kW PV >>>> array generates about 800W despite the low midday solar elevation of >>>> just 26 degrees. >>> >>> Thus the zenith distance would be 64 degrees. >>> >>> At Christmas, the solar declination is -23.5 degrees, >>> >>> Thus, your friend must be living at 40.5 degrees latitude (Barcelona, >>> Athens) latitude. >>> >>> In Spain, there are several solar thermal electric powerplants in the >>> few megawatt class. >> >> you will know when solar PV have "made it" (become economical) when >> you see the factory that makes them, has them on the roof and doesn't >> use much power from the grid.. > >That is an excessive requirement. It becomes worthwhile when the total >energy payback on solar is 10-100x that of manufacture. At the moment it >is around 6-8x for PV and rising so there is hope for it yet. > >OTOH at my latitude where the sun barely makes 12 degrees above the >horizon at midday in mid winter PV is pretty useless. The PV powered >"warning bend - skid hazard" roadsigns tend to die a horrible death >every winter if they are not totalled first by some speeding nutter. > >Kind of sad really - they work brilliantly all summer when there is no >frost and lots of sunshine and as soon as winter comes they run out of >battery power about an hour after sundown even on sunny days. > >Regard, >Martin Brown They should put little wind motors (generators) on them too then. |