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#145945 - 08/12/06 12:51 PM Photovoltaic Panels
Alan Belson Offline
Member

Registered: 03/23/05
Posts: 1801
Loc: Mayenne N. France
Photovoltaic [pv] panels to generate electricity have been in the UK news recently;- http://www.currys.co.uk/solarpower/index.html
[Currys is a large UK electrical retailer.]

The system they are selling is by 'Sharp'.
Summarised, from their website;

Roof mounted panels: Currys quote a value of 1600kWh/annum produced from a 'typical' system having a rating of '2kWp' (whatever that means. They say it means 1kWp = 800kWh/year! 2x1 = 2 ). The pv units carry a 25 year warranty. The panel[s] supply dc output to-

An externally placed inverter. This creates ac of poco 'quality' and sync, which feeds to-

A 'production' meter, feeding power direct to the National Grid. Customers will be paid/credited for this power. [ Not all of the present UK pocos, some of whom are actually just 'brokers', will do this; a customer may need to change to a company that will. ]

The poco supplies electricity to the customer from the Grid via a second 'consumption' meter.

Note; There are no batteries, the customer is still Grid connected, and all the power actually consumed in the home comes from the Grid.

Technically, this is quite a neat scheme. It retains the security of being Grid connected and it retains the home's existing panels/fuses/breakers and other safety features etc.. There is no battery system, which reduces complexity, maintenance, storage and first cost. As long as the Grid is up, you have power. You have power at night, and your pv generation to the Grid is paid for. At what price per kwh is not revealed, of course.

Furthermore, Linesmen safety is assured because the system shuts off automatically in the event of a power outage; it won't backfeed the local transmission lines.

Quote: " There is no product that can be added to [the] pv system to act as a back up at the present time".

The present cost is 'from' £9000 for a 'complete package' generating about 1600kWh per annum, and consisting of 9 arrays and all the necessary kit, fitting, wiring etc..
Currys are naturally reticent about payback, and waffle a bit about 'increased house-values', a much cherished UK phenomenon; but I reckon straight payback, based on power generated, at about 66 years at present UK power prices.

Solar power arriving on Earth as light, [ ie photons, the 'fuel' of these devices], is quoted at about 1 kw/ square metre, [1 kw/ 10 sq. foot] in mid-lattitudes. Efficiency of conversion is about 10-15%. One US website quotes an output of c 10.75W/sq. foot, or 1kw per 93 sq foot ( ie. a square of 9ft 6" sides ) of panels. This would vary during the day /time of year/ lattitude, of course. Prices per square ft. vary enormously, as you would expect, but a price of US$6000 per kw output [US$65 a square foot] has been seen quoted on the net.

All I can say is, they are not going to get killed in the rush on those figures. The cost has to come down, perhaps through grant aid / tax breaks?

Alan
_________________________
Wood work but can't!

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#145946 - 08/12/06 01:14 PM Re: Photovoltaic Panels
SteveFehr Offline
Member

Registered: 03/19/05
Posts: 1192
Loc: Chesapeake, VA
I did some calculations a while back. The problem isn't the cost of the panels, it's that the sun really doesn't put all that much energy onto the earth- we would have to pave an incredibly large number of square miles of earth to satisfy the energy needs of a major western nation.

FYI, it would literally take a solar panel larger than Wales to supply UK with your annual electrical consuption. And probably require most of Scotland to be turned into hydoelectric resevoirs to feed the grid at night and on rainy/cloudy days.


Assumptions/Constants:
* Average Solar Flux for North America: 150 W/m2 -This is representative of the US Northeast and Europe, and accounts for weather.
* Best Average Solar Flux in the US southwest is 240 W/m2
* Northern US December average 71 W/m2
* Winter levels will be appx 80% of this value
* US Annual Energy Consumption in 2003: 6.22 ExaWatt-hours (equivilent to 325 billion tons of oil)
* Typical electrically heated household energy use during coldest week of winter: 24,000W
* Typical instantaneous power requirement for a refrigerator: 1200W
* Combined contribution of solar, geothermal and wind in 2003: less than 2%
* Solar Panel Efficiency: 8.25% (commercially mass produced a-Si, the only feasible material at the scale we're talking! See Unisolar whitepaper #1 below.)
* Thermal de-rating of solar panels for US winter weather: 15% for a-Si, 35% for crystalline silicon.
* Typical loss due to dirt, dust, etc: 3%+
* Inverter efficiency: 94%
* Wiring efficiency: 97%
* Transformer efficiency: 95%
* Battery efficiency: 80%

* Energy required to manufacture a-Si panels:120 kWh/m2 (432 MJ/m2) as a generously conservative estimate. I don't know if this counts mining, refining, transportation, installation, cabling, power conversion, substations, transmission, etc, etc and I'm pretty sure it doesn't.
* Energy required to mount an a-Si panel: appx 120 kWh/m2 (432 MJ/m2)

* Solar energy absorbed annually per m2 in US Southwest desert:
365 days * 24 hours * 240W/m2 = 2,100 kWh

* Solar energy absorbed annually per m2 in US Northeast:
365 days * 24 hours * 150W/m2 = 1,314 kWh

* Losses in conversion, wiring, etc:
.97 * .94 * .97 * .95 * .80 = 32% loss, 67% efficiency

* Break-even point for energy for a-Si Solar Panels and installation in US Southwest desert:
240kWh/m2 / (240W/m2 * 8.25% * 67% * 24 * 365) = 2.1 years

* Break-even point for energy for a-Si Solar Panels and installation in US Northeast:
240kWh /m2 / (150W/m2 * 8.25% * 67% * 24 * 365) = 3.2 years

For this that missed the significance of this, it means spending 2-3x our entire annual energy consumption on solar panel production alone.

If the south-facing roof of a 200m2 (~2000ft2) typical house in the Arizona desert was covered in a-Si solar panels:
240W/m2 * 100 m2 * 8.25% * 67% = 1300W (about enough to run a refrigerator)

If the south-facing roof of a 200m2 (~2000ft2) typical house in the US was covered in a-Si solar panels:
150W/m2 * 100 m2 * 8.25% * 67% = 829W (about enough to run a typical PC desktop with 17" CRT monitor). It would take 42 houses like this to provide the energy one house requires for electric heating.


If the south-facing roof of a 200m2 (~2000ft2) typical house in the US Northeast in winter was covered in a-Si solar panels (assuming no snow):
71W/m2 * 100 m2 * 8.25% * 67% * .85 = 321W (4 houses combined could run a Mr. Coffee). It would take 75 houses like this to provide the energy one house requires for electric heating.

Cost of 8% efficient a-Si solar panel: appx $1000/m2
Cost of installation: appx $100/m2
Cost of 10kW inverter: $12000 (For surge. An electric range draws 10kW.)
Cost of storage batteries: $200/kWh
Cost of cabling: appx 1x material cost
Cost of electrical installation: appx 2x electrical material cost

100m2 of solar panels: $100,000
Cost of panel installion: $10,000
Batteries required to store 2 day’s worth of energy at 1300W average: $13,000
Cost of inverter: $12000
Cost of electrical installation: $50,000
Total cost of 1300W Arizona or 564W northeast partially-solar-powered house calculated for above: $185,000.

Area of solar panels in the southwest US desert required to supply US with total electricity demands:
6.22Ewh / (1300W * 24 * 365) = 54,000 km2

Number house-sized solar panels spread evenly throughout the US required to supply US with total electricity demands:
6.22Ewh / (829W * 24 * 365) = 856 million house-sized panels (compared to 120 million households in the US, which includes aparments and townhouses)- works out to about a quarter acre of solar panels per every family in the US. BUT, that's lopsided as most of that comes from the summer. If we go by straight winter values, it works out to closer to 17 acres of solar panels per family.

US GDP: $ 11.75 trillion
856 million house-sized panels: $158 trillion



Sources: http://www.eia.doe.gov/emeu/cabs/usa.html http://www.johnstonsarchive.net/environment/solartechnote.html http://www.uni-solar.com/uploadedFiles/0.4.2_white_paper_2.pdf http://www.uni-solar.com/uploadedFiles/0.4.2_white_paper_1.pdf http://www.nrel.gov/docs/fy04osti/35489.pdf http://en.wikipedia.org/wiki/Solar_power


Since we're using very large numbers here:
1,000 Thousand Kilo k
1,000,000 Million Mega M
1,000,000,000 Billion Giga G
1,000,000,000,000 Trillion Tera T
1,000,000,000,000,000 Quadrillion Peta P
1,000,000,000,000,000,000 Quinillion Exa E

[This message has been edited by SteveFehr (edited 08-12-2006).]

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#145947 - 08/13/06 12:26 AM Re: Photovoltaic Panels
Alan Belson Offline
Member

Registered: 03/23/05
Posts: 1801
Loc: Mayenne N. France
Excellent response Steve.
It is going to take me a while to wade through all that info, but a few points-

1. The Sharp/Currys system does not claim to produce all the electrical power in a UK home. At an average 3300kWh/annum UK electricity consumption, a 1600kWh/annum system would produce roughly 50% of it.

2. Based on an average European solar radiation at surface of [say] 1000kWh per sq.m, and 8.5% conversion x 67% efficiency, then to produce 1600kWh/year requires c.28 sq m of panels = 9 panels of c. 3 sq.m.
So, the system is technically viable for what it aims to achieve, it is just too expensive.

3. Most UK homes use fossil fuel for heating, with very poor insulation in most of them. I quite agree that to expect pv cells to generate enough electricity to run all the home-energy requirements of our existing housing stock is impossible.

4. Cover Wales in pv cells?
What a tempting notion!

Alan
_________________________
Wood work but can't!

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#145948 - 08/13/06 12:30 PM Re: Photovoltaic Panels
SteveFehr Offline
Member

Registered: 03/19/05
Posts: 1192
Loc: Chesapeake, VA
Yeah, most solar houses cheat by using gas heating and cooking. I say BAH! If we're trying to go all solar and energy independant, you don't use fossil fuels for heat. So, with that in mind, I don't like to use the "average" household power requirements. Of course, I'm still using the overall US electrical consumption- if we went all electrical for heating and cooking, we'd likely need far more panels than I've estimated for...

Last forum I posted this on had no problems with most of my calcs, yet horribly balked and decried my $50k estimate for electrical installation costs at industry standards, including O&P and subcontracting fees. I was figuring watertight conduit and cabling run on a roof under solar panels as being extremely expensive, not to mention the cost of installing the inverter and battery bank. But I never actually sat down with Means to do a proper cost estimate, and if panels were designed for series connection or with integral power channels, that would drop the cost considerably as well. Perhaps someone else here would care to take a stab at a more accurate estimate of installation cost? Anyone here done any solar installs that might be able to help with a basis of comparison?

[This message has been edited by SteveFehr (edited 08-13-2006).]

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#145949 - 08/16/06 12:57 PM Re: Photovoltaic Panels
Alan Belson Offline
Member

Registered: 03/23/05
Posts: 1801
Loc: Mayenne N. France
Some research reveals that grant-aid, towards the cost of purchase of 'reducing carbon emissions equipment' , [such as pv panels ], is available in the UK and France as part of Kyoto accord. So it's probably available across the EU.

UK. Grants are available for pv panels, wind generators, hydro, etc. with provisos like mandatory additional improvements in insulation, fitting double glazing, auto furnace-controls, etc..
For pv, the grant is £3000 per kWp, up to a max. of £15000, but not more than 50% of the installed cost.
http://www.lowcarbonbuildings.org.uk

Not available in the IOM or the Channel Islands, and not available retrospective of existing purchases.

France. A very much simpler sheme, [ for a country so in love with dossiers and bureaucracy!]. Simply purchase/have fitted any energy/CO2 saving device - loft insulation, double glazing, condensing boiler, geothermal heating, pv panels, solar heating, wind turbine, closed wood-burning stove, etc., and get between 15% and 40% of the cost (less labor) knocked-off next year's income tax, on production of a receipt; pv attracts the 40% remise. Receipts are simply stapled to your annual tax form. Mine went in last month!
If you pay little or no tax, they send you a cheque instead!
The wood-burner counts, because the CO2 comes from a resource renouvelable

I'm off down the Hotel des Impots [tax office] tomorrow to see if I can get a cheque for the 200 sq metres of rockwool I just put in the remodel!

Alan
_________________________
Wood work but can't!

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#145950 - 08/16/06 02:09 PM Re: Photovoltaic Panels
SteveFehr Offline
Member

Registered: 03/19/05
Posts: 1192
Loc: Chesapeake, VA
We can tax-deduct certain energy saving materials in the US, too.

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#145951 - 08/19/06 06:52 AM Re: Photovoltaic Panels
Trumpy Offline

Member

Registered: 07/05/02
Posts: 8540
Loc: SI,New Zealand
Alan,
Good thread mate!.
I've said here before about a mate of mine that has a solar system that he derives power from to run 90% of his power needs.
He still has the mains running to his house and he uses it for the occasional running of his range and the washing machine.
Where his is different, however, is that his is totally independant of the mains supply, the systems are seperate.
He has (I think) 9 panels, feeding into an array of 2V cells (Ex-Telecom cells) wired in banks to give a 12V output to a 2000W Sine Wave Inverter.
He has a heap of current monitors and all sorts of other gear associated with it, it's pretty involved.
He did have an ordinary old Square wave inverter when he first started the system, but the local Radio Inspector pinged him for excess RFI, it was found that the Inverter was radiating a signal that could be measured quite a way down the street!.
Bear in mind though, that this guy doesn't use a lot of power, he lives by himself and has a fire to heat his water and his house is so well insulated, it's a wonder the bricks haven't started popping out of the outside walls.
His favourite question at Radio club meetings is:
How much was your power bill last month?.
He only pays a few dollars above the line charges, it makes me sick.
_________________________
Let's face it, these days if you're not young, you're old - Red Green grin

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#145952 - 08/21/06 03:33 PM Re: Photovoltaic Panels
Alan Belson Offline
Member

Registered: 03/23/05
Posts: 1801
Loc: Mayenne N. France
Just been looking at an interesting alternative idea.

Iceland has an unused potential hydro electric capacity of vast size, [ 26-31 TWh / year ] which the government there wants to export to Europe.
They also have 14TWh / year of unused geothermal.

The idea is this; instead of running a bit of bell wire to Sweden and all points south, make aluminum from bauxite instead using hydro-geo power. This would be shipped in 20,000 ton cargos to Europe/N. America where the electrical energy in the aluminum would be reconverted. All 280GWh of it.
BTW 'Google Earth' is a good way to get an idea of the distances involved.

Aluminum represents 6.4 kWh of electricity per pound of the metal. It's a safe non toxic cargo.

Once the electricity has been created and fed into the Grid, the aluminium hydroxide waste-product, ( ie bauxite sludge ), formed in the reaction is shipped back to Iceland and made into ....er...aluminum! The sludge is high value, because it is pure. The preparation of raw bauxite for the smelters involves costly removal of impurities like iron and silica.



Hey! Can we run cars on aluminum wire?

"Fill 'er up! 200 lbs of #6!"

Alan

delete duff link

[This message has been edited by Alan Belson (edited 08-21-2006).]

[This message has been edited by Alan Belson (edited 08-21-2006).]
_________________________
Wood work but can't!

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#145953 - 08/21/06 04:32 PM Re: Photovoltaic Panels
classicsat Offline
Member

Registered: 11/23/02
Posts: 449
Hydrogen might be a better idea, although a little more unstable than aluminumm, it is easier to haul, and easier to convert back to electicity, with no bauxite sludge to return.

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#145954 - 08/22/06 02:05 PM Re: Photovoltaic Panels
Alan Belson Offline
Member

Registered: 03/23/05
Posts: 1801
Loc: Mayenne N. France
Many types of poweful aluminum batteries have been built in the last 50 years, and it's true that formation of bauxite sludge/gel is a major bottleneck to releasing the potential of this metal's capacity to store energy.
I read a follow up report that a new battery is being claimed, by Europositron in Finland. This is an Aluminum battery with a claimed density of 1330Wh/kg, 3000+ cycles, life 10-30 years and -40F to + 159F working temperature and which claims to sidestep the hydroxide sludge barrier.

This is BTW only about twice the capacity of Glen Amatucci's Telcordia Technologies [Morristown NJ] 2002 patent No 6,482,548 claim for an Al-Li cell, so not outside the realms of reality.

If giant batteries can be made economically to transport electricity by ship from hydro plants, there is no sludge to carry back, just enough charge for the electric propulsion units to return the ship to the hydro power station's distributors.
http://www.europositron.com

Alan

[This message has been edited by Alan Belson (edited 08-22-2006).]
_________________________
Wood work but can't!

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