Talk:Photovoltaics

Serpa power station finished

The Serpa power station is inaugurated today, 28/3/2007, so I edited the table. The source is in [1], but in Portuguese only. Dreixel 11:49, 28 March 2007 (UTC)

current developments

Given the recent breakthroughs in transitor development cited by IBM and Intel using hafnium, I would like to see some discussion of how the use of hafnium in photovoltaics is currently researched, existing hafnium supplies, etc.

- - - -

should be in the PV cell section --Oldboltonian 11:49, 1 June 2007 (UTC)

technology

There is no information about how photovoltaics work, different photovoltaic technologies, and the article lacks any mention of the photoelectric effect. This article feels like an economic and environmental argument for photovoltaics, rather than a balanced article of all aspects of photovoltaics.

- - - -

Need a coherent structure between the articles

PV cells PV modules (lost in solar panels) PV arrays (lots of good background) Photovoltaics (this article)which covers more the practical aspects of operation --Oldboltonian 11:42, 1 June 2007 (UTC)

historical price information?

Do folks think it would be helpful to show how the cost of PV hs been coming down as production has increased? Also, there is currently very little info on the technology itself. I.e., might a discussion of crystal silicon, amorphous silicon, CdTe, CIGS, etc be helpful? --Bikechess 21:17, 27 August 2006 (UTC)

I think they decided to have the technical section under Solar Cell. The price-per-watt in dollars is on the Solar Energy page with a source. It could be copied here. 82.93.133.130 10:18, 30 November 2006 (UTC)

Here is one: Photovoltaic Electricity in Hawaii (page 3) —The preceding unsigned comment was added by 212.202.73.243 (talk) 21:45, 12 December 2006 (UTC).

There is one interesting article in a blog that takes the issue of price in the years gone by. [[2]] Go down to Glittering future of solar energy post and you'll be there. Arkitektpt 11:08, 11 July 2007 (UTC)

rewrite

I have rewritten the introduction and am planning to move text in here from the solar power article in order to address the confusion in that article between PV and solar thermal. Please comment either here or on the solar power talk page.Itsmejudith 16:10, 20 July 2006 (UTC)

Sounds good to me. Am I right to assume that a large chunk of solar panel needs to be moved here as well?

Also, I envision a more complete ROI calculation somehwere on WP, will that be in this article? I made some corrections to the computations done in the article solar panels, but did not apply and dollar values to the figures. linas 20:17, 22 July 2006 (UTC)

OK, I've made major reshufflings. Solar panel is a disambiguation page, pointing to either solar hot water panel or to solar electric panel, which is a redirect to photovoltaic array, which is defined to be just a panel assembly of solar cells. I'm thinking the politics, and the major applictions, and etc. will be in this article. linas 22:05, 22 July 2006 (UTC)

Agree with your last comment. As for "array", my understanding is that an assembly of solar cells makes up a panel, or module. An assembly of modules is an array. I'm not sure that one module on its own would be called an array. Solar electric panel would perhaps be the place to discuss the different types of panels that are available - laminated, framed, unframed etc. I'll have another look through the whole series and comment again here. Itsmejudith 09:37, 23 July 2006 (UTC)

It would help undertanding to describe a PV system in its entirety here: Modules, inverters (for grid connected), cables, fixing systems etc.Oldboltonian 22:28, 28 October 2006 (UTC)

average cost per installed watt

As of early 2006 average cost per installed watt has decreased to about $4.50.

Should it say in which currency the 4.50 is in? Presumably the author lives in the USA?

A cited source for the figure would be good, too. --Nigelj 11:05, 30 July 2006 (UTC)

HowStuffWorks mentions a much higher cost: http://home.howstuffworks.com/question418.htm

Have a look at http://news.bbc.co.uk/1/hi/technology/5234402.stm for something a bit more realistic and probably much more recent, I think. --Nigelj 19:09, 4 September 2006 (UTC)

The $4.5~/Wp sounds about right to me. Remember there is a difference between cost and price. Price can be higher or lower, depending on level of profits for the seller and subsidies, if available.Jens Nielsen 12:14, 29 June 2007 (UTC)

Cost and price are currently decoupled due to excess of demand v supply. Price is determined largely by the feed in tariff in Germany (90% of European market and 40% of world market. Cost is determined by learning curve of silicon mfr, wafering, cell and module manufacture.--Oldboltonian 22:24, 29 June 2007 (UTC)

Source data for PV Power Costs?

Anyone know what the source for this infor is/was? The fact that the decimal places are commas is a bit confusing. Also the statement "Normally photovoltaic equipment is fully functional after 30 years also." is a bit weird. Does the author mean "fully profitable"? Or paid for? -KevMoo 18:55, 6 August 2006 (UTC)

I changed the sentence to what I think it means - PV equipment should last 30 years or more, not just 20. I also changed the decimal separator to point. But this table can't stay unless there is a source cited, in case of copyvio. And the introductory paragraph still makes no sense. And I am still not sure how the table is meant to be read. Other than that, fine! ;-) Itsmejudith 20:12, 6 August 2006 (UTC)

This is my table. I created it. You read it the following way: The costs depend on the sun power you have in your country. For example in south Germany it is 1,000 kWh/year or in Spain and Sicily it is 1,800 kWh/year. California should be about 2,000 kWh/year in some regions. After that you must know how much you paid for your photovoltaic equipment and then you can see how much a kWh costs for you in cent/kWh. Here in germany we will soon produce solar modules for about 1,000 €/kW_p. The costs for customers are much higher cause the firms must grow very fast. Take a look at the german article too de:Fotovoltaik there's much more information about photovoltaic. The calculation is the following for 3,000$/kW_p, 2000 kWh/year, 4% interest and 1% cost of operation: Money costs: 3000$ * 0.04 = 120$/year, depreciation: 3,000$/20 years = 150$/year, cost of operation: 3,000$ * 0.01 = 30$/year, sum: 120$/year + 150$/year + 30$/year = 300$/year. Now devide 300$/year through the kWh/year ==> 300$/year / 2,000kWh/year = 15 cent/kWh. That's it. At the moment more as 500 million persons boost PV (most of them in europe), so 100 billion dollar isn't really much money per person. Take a look at the mobile phones, digital cameras or TFT displays. Economy grows very fast if there are several billion dollars to earn. At the moment we spent 2326 billion dollars a year for oil (75$/barrel). --212.202.193.176 10:08, 8 August 2006 (UTC)

Solar panels cost a lot more than 1,000 Euro per Kw. Here in the Middle East they are around 15,000 Euro per Kw excluding installation. Also the calculation doesn't square with the UK estimates earlier which suggest it takes 130 years to just recover the capital costs. Curry's also mentioned above quote starting prices at 12,000 Euro!--Rjstott 10:39, 8 August 2006 (UTC)

The production costs in germany are 2,000€/kW_p and on the market you can buy 93.1 kWp for 337,953€ (532 modules, 175 Wp, single crystal, 40" container, CIF Hamburg). This is 3,630€/kW_p. But 1,200€/kW_p are silicon costs cause we use chip silicon at the moment. Now the production uses solar silicon which is about 70€/kW_p. So in the near future production prices could be lowerd to 1,000€/kW_p and more due bulk production. Bulk production reduces production prices by 20% if you double the production. And we must double the production at least 10 times. Thin film moduels (amorphous silicon) are at 2,800€/kW_p at ebay: [3](scroll down to the middle of the page). If you pay 15,000 € per kW_p better ship your modules from germany.--212.202.193.176 11:37, 8 August 2006 (UTC)

Here is an auction for 7.26 kW_p [4].--212.202.193.176 14:26, 8 August 2006 (UTC)

I'm sure you will be right about panel prices some time in the future. What matters here surely is a like for like comparison of the situation now. To do that you would have to include the costs of the necessary regulators and power inverter, delivery, plus installation using actual prices including profits now. This is very topical and interesting and an article detailing practical installations with some good facts would be very useful. We're buying Kyocera panels and the prices I quoted included regulator, battery, enclosure and wiring. Delivery is a significant cost as is profits to various middlemen who add little value. Neither BP nor Shell can match the prices and all companies report significant back-order situations. For the time being price is determined by market forces similar to those driving oil prices where currently a factor of five or more can be found between extraction costs and market price.--Rjstott 03:43, 9 August 2006 (UTC)

We're still missing a source for the table, correct? Please include one. KevMoo 04:36, 12 August 2006 (UTC)

There is no source for this table. You can calculate every value as I described it above. So the source is Microsoft Excel or your pocket calculator. And yes, you have to calculate all your costs of course, not only the module price. If you are grid connected, you don't need batteries. You supply surplus power to the net and get money for it. In Germany, France, Spain and Italy this is about 50 eurocent/kWh. If you need batteries you must calculate them to the costs/kWp of course. If you are grid connected you have additional costs for the inverter. For example: Module costs: 40.000$ (10kWp), inverter: 2.000$, installation: 8.000$. So your costs are 5.000$/kWp. Now the auction ([5]) ends at 4422 Euro/kWp. It includes all, modules, inverter, cables and mountings for self-construction. So in Sicily (1800kWh/year) you can produce power for 24 eurocent/kWh. Net power costs are 21.08 eurocent/kWh. Here you can buy modules for 3,49$/Wp [6] and thin film ones for 3$/Wp.

Excel

$D$1=0.04
$E$1=20
$F$1=0.01

B5: 2400
C5: 2200
D5: 2000
E5: 1800
F5: 1600
G5: 1400
H5: 1200
I5: 1000
J5: 800

A6 : 200
A7 : 600
A8 : 1000
A9 : 1400
A10: 1800
A11: 2200
A12: 2600
A13: 3000
A14: 3400
A15: 3800
A16: 4200
A17: 4600
A18: 5000

First cell: =$A6*(($D$1+$F$1)+1/$E$1)/B$5*100

--212.202.193.176 18:00, 12 August 2006 (UTC)

Here is another calculation from diablosolar: [7]--212.202.193.176 20:49, 12 August 2006 (UTC)

I had to study the chart and read this commentary and re-study the chart before I comfortably understood what it represented. I suggest adding the following wording as introduction to it. "The label at the left end of each row shows an example price ($US) per peak Kilowatt hour (kWp) of a PV panel. The column headings indicate the actual kilowatts of production to expect from the panel. This varies by geographic region. The calculated values reflect the cost in $US cents per KwH produced, considering a 4% cost of capital, a 1% operating cost, and a 20-year lifespan of the equipment. "

comments? Leotohill 04:14, 28 August 2006 (UTC)

I think that's good and just suggest a few small changes to clarify it a little more:

The labels on the left show various total costs, per peak kilowatt (kW_p), of a PV installation. The headings across the top refer to the annual energy output expected from each installed kW_p. This varies by geographic region and according to efficiency etc. The calculated values reflect the total cost in cents per kWh produced, including a 4% cost of capital, 1% operating and maintenance cost, and depreciating the capital cost over 20 years. Normally, photovoltaic modules have 25 years warranty, but they should be fully functional even after 30-40 years.

BTW, did you also see my, and the original author's, re-calculated examples near the bottom of this page? --Nigelj 19:23, 28 August 2006 (UTC)

I've added the paragraph, more or less as above, to the article. --Nigelj 20:12, 30 August 2006 (UTC)

This still needs work--the table has no title or caption--one has to dig through the text to find a description of it. The table needs better labeling.70.109.143.5 00:44, 29 October 2007 (UTC)

Deployment of Solar Power

This section contains all kinds of solar power not just Photovoltaics and should be in an article on its own. Lumos3 09:07, 8 August 2006 (UTC)

Suggestion for Public Service sites (counter part to Companies section)

This section may contain all applications related to design, installation, operation, testing, etc. of photovoltaic systems. There exist government, commercial or non-profit funded sites offering web applications-applets that are useful for owners, would-be owners, or operators of photovoltaic systems. This section would serve as a portal for the splintered resources, or as an outlet for new contributors; a counter part to the 'Companies' section. Swbyang (talk) 10:28, 28 November 2007 (UTC)

100 billion Dollars left

My information was reverted. What are the reasons? The rest of the costs to get this technik cheeper as Fossil fuel are about 100 billion Dollars or 10$ a year 10 years long for 1 billion persons in these countries. This is the same amout of money we worldwide spent for oil in only 16 days.--212.202.193.176 23:33, 8 August 2006 (UTC)

The claim is valid enough to include and is seen in several major publications. I can offer sources if needed. Jens Nielsen 06:01, 31 August 2006 (UTC)

I have no idea what's being discussed here. Would someone explain? Leotohill 22:11, 31 August 2006 (UTC)

PV profitable without subsidy in Italy since 2006

Can anyone put this section to good english. It is from the german article de:Fotovoltaik

How about:

In Italy PV power is cheaper than retail grid electricity since 2006. One kWh costs 21.08 -€cent/kWh. Italy has an average of 1,600 kWh/m² (Sicily even 1,800 kWh/m²) sun power/year. At 4 % costs of capital, 25 years of depreciation and costs (including installation) of 4,600 €/kW_p PV current costs are 20.91 €-cent/kWh. At large scale plants with 3,900 €/kW_p the costs reduces to 17.75 €-cent/kWh and is 15 % cheaper. To reach a 19% PV power coverage in Italy, 34,000 MW_p power must be installed. This means 0.09 % of the size of Italy. 9 % of the size of Sicily could produce 25 % of the power of the complete European Union (ca. 2,100 TWh/year).

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I also calculate Italy to be the first country in EU to reach grid parity, with second highest retail However I heard grid electricity prices vary considerably from one region to another. Anyone got any data on that?

Eurostat carries EU - 25 retail electricity prices

consumer electricity prices (EURc/kWh)

Denmark 23.62

Italy 21.08

Netherlands 20.87

Germany 18.32

Luxembourg 16.03

Ireland 14.9

Slovakia 14.48

Belgium 14.42

Sweden 14.35

Cyprus 14.31

Portugal 14.1

Austria 13.4

France 12.05

Poland 11.9

Spain 11.47

Finland 10.78

Hungary 10.75

Slovenia 10.49

United Kingdom 10.2

Czech Republic 9.85

Malta 9.49

Latvia 8.29

Estonia 7.31

Lithuania 7.18

Greece 7.01

Oldboltonian 20:43, 26 October 2006 (UTC)

Power costs

I'm interested how much electric power costs in other countries. In Germany we pay about 18 €-cent/kWh and Italy is 21,08 €-cent/kWh. How much do you pay in your country?

Here's a link to power costs in Texas today. http://www.electricitytexas.com Costs have recently skyrocketed - 2 years ago we were paying under $0.08/kWh. Now it's about $0.144/kWh. So if I go here: http://www.oasismanagement.com/eurodesk/eurocalc.html ... Looks like you are paying almost double what we pay in Texas, and 3x what we were paying 3 years ago. Wonder why the difference? Taxes maybe.

Yes, there are a lot of taxes on our energy prices. Today (2006-10-26) gasoline prices are at $5.76/gallon and as I can see on gaspricewatch you pay $2.20/gallon. This is 2.6x higher. So why do you worry? :)

I think it would be good to add just a few words (maybe one sentence) of general intepretation to the data provided in the "PV power costs" table. As it is, it takes a while to begin to comprehend what it's telling us — and I believe it would be better if some explanation or interpretation were added. That way someone (say, an interested but uninitiated high-school student) coming to this topic for the first time could more immediately understand the data provided. Sentence could be added in either before or after the table. Joel Russ 15:03, 14 August 2006 (UTC)

OK. Add something like this (example calculation):

Parameters

Equipment + installation: 5,000$/kWp

Yearly sun power per kWp: 2000 kWh/year

Interest: 4%

Depreciation: 20 years

Operation: 1%

Calculation (for the first 20 years)

Money costs (interest): 5,000$ * 0.04 = 200$/year

Depreciation costs: 5,000$/20 years = 250$/year

Costs of operation: 5,000$ * 0.01 = 50$/year

Sum: 200$/year + 250$/year + 50$/year = 500$/year

==> 500$/year / 2,000kWh/year = 25 cent/kWh

Calculation (from 21 till the end)

Costs of operation: 5,000$ * 0.01 = 50$/year

==> 50$/year / 2,000kWh/year = 2.5 cent/kWh

Or you can calculate with 10 years also:

Calculation (for the first 10 years)

==> 750$/year / 2,000kWh/year = 37.5 cent/kWh

Calculation (from 11 till the end)

==> 50$/year / 2,000kWh/year = 2.5 cent/kWh

--212.202.193.176 23:24, 21 August 2006 (UTC)

Right, I'm trying to understand this, but I'm not sure the units of the results are at all clear:

Parameters

Total cost of equipment plus installation: $5,000 for each installed kW

Energy yield: 2000 kWh per year for each installed kW

Interest: 4% per year

Depreciation: 20 years

Operation and maintenance costs: 1% of total cost per year

Calculation (for the first 20 years)

Interest on total cost: $5,000 * 0.04 = $200 per year for each installed kW

Depreciation costs: $5,000/20 years = $250 per year for each installed kW

Cost of operation and maintenance: $5,000 * 0.01 = $50 per year for each installed kW

Sum: $200 per year + $250 per year + $50 per year = $500 per year for each installed kW

Therefore, $500 per year for each installed kW / 2,000kWh per year for each installed kW = 25 cents per kWh

Calculation (from year 21 till the end of the life of the system)

Cost of operation and maintenance: $5,000 * 0.01 = $50 per year for each installed kW

Therefore $50 per year for each installed kW / 2,000kWh per year for each installed kW = 2.5 cent per kWh

Is that right? There is too much abbreviation in the original example above (and also in the table that is currently in the article).

One more question, what exactly is the 'p' in kW_p meant to stand for?

One final question, even if this actually makes sense, is this too close to original research, or is it an encyclopedic elucidation of some self-evident facts, and so valid? --Nigelj 18:04, 22 August 2006 (UTC) -- Modified Nigelj 20:43, 23 August 2006 (UTC)

Yes, everything correct. The 'p' stands for 'peak'. It's needed to normalize test conditions. You're measuring at 25 °C and 1000 W/m² irradiance (STC-conditions, STC is short for standard-test-conditions). Sorry, but I don't know the answer of your last question. :(--212.202.193.176 23:33, 24 August 2006 (UTC)

Something wrong with the units of all these figures

There's still something wrong with this table and the section that has grown around it. Today, Eric Kvaalen has changed all the column headers from kWh/year to h/year on the basis that, I think he says, there was an implied "per installed kWp" in there that cancelled so that "kWh/year per installed kWp" becomes, dimensionally, just h/year. He may be right dimensionally, but what about the scaling multiplier that relates kW(actually generated) to kWp(installed capacity, under reference conditions)?

I'd let him off except he's gone ahead and changed the units of all the country-related data below too, to h/year. Where did this country data come from? What units were they in when gathered? You can't just change the units of someone else's measurements because it looks neater to you! If we have no source for this country data, shouldn't we just delete it all?

A factoid like "South Germany: ~900-1,130 h/year" sounds like it's a measure of the hours of sunshine per year there, but at what power? What angle of incidence through the atmosphere? What about hazy sun? Is this a way of measuring insolation? The insolation article has examples in W/m², which makes good sense. Unfortunately they're in the same numerical range as the figures on this page (e.g. 1350 W/m²). If we have figures here that were measured in W/m² and we're now quoting them in h/year, we have gone seriously wrong and this all needs deleting until some people who have access to citable sources get together on this talk page and put it all square. --Nigelj 18:57, 13 October 2006 (UTC)

Most people in the PV world talk kWh/kWp per year, since earnings from feed-in tariffs are calculated in money/y, and PV modules are sold by kWp

It's therefore not helpful to simplify kW.h/kW.y. For a mathematical purist, the yield should be dimensionless number, thus

1000 kWh/kWp.y = 0.1142 yield

Oldboltonian 21:15, 26 October 2006 (UTC)

Thanks for that. I agree with you (and the person who made this change hasn't been back to put any case) so I've changed the article back to these more meaningful units. Do they look right to you, now? More importantly, do you have any access to any viable source(s) that we can cite for these figures, or for this kind of calculation, in the 'PV world'? --Nigelj 21:48, 26 October 2006 (UTC)

The units are OK. The content of the table is simply a calculation, based on some assumptions (which are reasonable). No citable source needed, not original research.

The country numbers kWh/kWp given below the table however need to be justified and explained. kWh/kWp.y is mainly a function of kWh/m2.y (or W/m2) of insolation and the efficiency of the module. There are other factors as listed in a BP Solar paper[8] which claims "kWh/kWp differences between correctly measured different technologies is small"

so what is needed is a list of insolation ranges of different countries and US states ( I think the country numbers in the list actually are insolation numbers not kWh/kWp.y. The NASA map at the head of the article can be cited for these.

To get to kWh/kWp.y, one must now calculate annual insolation * system efficiency, which is primarily module efficiency and a bit of inverter efficiency. There may be formulae for this in the public domain

An example from Sonnen in Bavaria [9] quotes for a park built with Sharp ND-Q0E6T (can't find specs for these but must be 12-13% module efficiency) and 94% efficient inverter.

1268 kWh/m2.y . . . 1746 kWp . . . 1775000kWh/y . . . yield = 1015 kWh/kWp

A second column in the country table could be populated either with actual data of kWh/kWp.y (as the example above) or calculated assuming typical efficiencies, eg module 13%, inverter 95%.

The cost data at the bottom is reasonable but there will be no citable source, as it is is not publicly quoted

Oldboltonian 22:23, 27 October 2006 (UTC)

Hello, this is Eric Kvaalen. I didn’t have a "watch" on this so I didn’t see the discussion.

The reason I changed the units in the chart (from kWh to h/y) was that when you take kWh/y and divide by kW(peak) you get h/y. This simply means that you get the equivalent of, say, 1000 hours of direct sun per year. Obviously this doesn’t mean 1000 hours of sun (anyplace on earth gets about 4383 hours of day per year and 4383 hours of night), but rather it takes into consideration the angle of the sun compared to the (optimally oriented) panel and the amount of cloudiness.

In the table giving data for different places, again, the units are kWh/(kWp year) which simplifies to h/y. I don’t know where the data are from, but a book I have (Other Homes and Garbage, 1981) gives a "capacity factor" of 0.209 for Santa Maria, California, which can be converted to h/y by multiplying by the number of hours in a year, 8766. This gives 1832 h/y. Together with the data referred to by Oldboltonian this seems to confirm that the numbers in the article are all right. (They are not average watts per square metre. To convert from average W/m² to kWh/kWpy you have to multiply by 8.766, using 1000 W/m² as normal direct sun. 1350 W/m² is the value above the atmosphere. After this is diminished by the atmosphere and clouds and the fact that the sun is usually not shining directly onto the panel, and then you multiply by 8.766, you get back to a similar numerical value—that’s all.)

I don't know if the kWp already takes into account the inverter losses or not.

By the way, I think the map at the beginning refers to solar energy falling onto horizontal surfaces, and is therefore not really relevant.

I will wait a few days for comments and then I will change the units again, because what's there now is just plain wrong. We could put kWh/(kWp y), but personally I prefer h/y because it's less clumsy.

EricK 20:28, 27 November 2006 (UTC)

Hi Eric. But what you're saying is pure original research WP:OR. What you "personally ... prefer ... because it's less clumsy" is completely irrelevant. What an encyclopedia gives is a report of what is currently known, used and done in the actual, real world. If, as Oldboltonian says, "Most people in the PV world talk kWh/kWp per year" and he has "An example from Sonnen in Bavaria" of them doing just that, then we must go with that for now. I say 'for now' because this part of the article is, in my opinion, hanging on by its fingernails until we can find citable sources for every base figure in the country table, and some justification that the calculated figures in the other table are realistic too. --Nigelj 20:51, 27 November 2006 (UTC)

I didn't do any original research! I agree with Oldboltonian that kWh/kWp per year is correct. If you insist, we will put that. I'm just saying that that is the same as equivalent hours of direct sun per year, so it would be simpler to use the label h/y.

As for the reference for the table, why don't you look back in the history and find who put it in and then ask him? It's important information and it would be a shame to delete it.

EricK 09:36, 28 November 2006 (UTC)

Eric and Nigel, the table is a simple mathematical calculation - would you require a citable source for a multiplication table or a mathematical function? Surely not.--Oldboltonian 07:56, 2 December 2006 (UTC)

Personally, I am still confused by the table, although I transferred it to this page from Solar power and made some style edits. My level of knowledge is as a user of PV. What I think would really help is an explanation of what the table is for, i.e. who would use it and when. Itsmejudith 09:54, 2 December 2006 (UTC)

I agree that the colourful table is a pure calculation, but its usefulness and meaning must be based on raw data in the list below, that I've been calling the 'country table'. A person living in, say, England, should be able to look up 'England' in the country table, find some figure (insolation level? Whatever, but verifiable and true with cited sources) and take it into the colourful table and say, "If I could get my solar system installed for, say, $3,800 per kWp, then I'd effectively be 'paying' x cents per Unit (kW-h) for my solar power. Now, is that worth it, to me?" From memory the concept and the basic idea was added a long while back by a German contributor (just an IP address, I think). It's had a lot of clean-up and debate since then, but it's still not finished or at its best, I think.

What I'd like to see, one day, is some verification that the derived figures in the calculation table actually bear out when compared to a few actual cases-studies reported somewhere. Case studies that say that someone, in some part of the world, has calculated their actual, installed PV energy costs and that our table would have predicted something similar. That would be really neat.

I once asked the person who created the colour-keyed insolation map of the world at the top of the article for some help tracking down raw and citable insolation figures for possible use in the country table, but never really followed up on his response. Maybe someone with time and energy could pick up on that? --Nigelj 13:33, 2 December 2006 (UTC)

See also http://www.ez2c.de/ml/solar_land_area/ --Nigelj 15:08, 2 December 2006 (UTC)

The article insolation has a reference that links to http://www.solar4power.com/solar-power-insolation-window.html which has a table for min max and avg insolation for a large number of US cities. NREL states that the average insolation for the US is 1800 KWhr/m^2/yr 199.125.109.97 22:54, 12 June 2007 (UTC)

References

The links to the references don't seem to be working and/or are not all the correct sort. I can't find where it first went wrong. Rmhermen 16:43, 7 September 2006 (UTC)

Largest PV plant planned

I'm not sure whether I should add this to the article. It is a project that is planned, but perhaps it would be prudent to wait until it is underway before adding it to the article proper.

ABC (Australia) News Item

Solar Systems Pty Ltd

Solar Systems Pty Ltd (Australia) and Boeing have applied for a Low Emission Technology Demonstration Fund for a 154 MW concentrated photovoltaics plant. If approved, it will be built in Victoria, Australia.

Ordinary Person 09:12, 12 September 2006 (UTC)

History

Perhaps someone could add something about the invention of PVs. Ordinary Person 05:13, 13 September 2006 (UTC)

Hi Ordinary. There is some history in solar cell. Do you think it should be brought over into this article? Itsmejudith 20:26, 17 September 2006 (UTC)

DIY Solar panels

As solar power still tends to be quite costly, aldough grid power aint cheap too and prices of PV modules are dropping, there are do-it-yourselvers who construct the panels themselves. In "Benin, Gambia, Ghana, Haiti, Kenya, Madagascar, Malawi, Malta, Mongolia, Nepal, Niger, Nigeria, Pakistan, Philippines, Sierra Leone, Tanzania, Thailand, Togo" projects are underway to construct PV's yourself. More info on following page: biodesign.co.uk

Please insert this info on the photovoltaics page or somewhere else on wikipedia,

thanks

Financial Incentives

The main driving forces for installing photovoltaic modules (or panels) are subsidies.

Germany pioneered this mechanism, Spain, Italy, Greece and France are other EU nations that have followed. The merit of feed in tariffs is the rewarding of overall annual power generation over the years; capital subsidies tend to encourage less reliable, cheaper equipement.

A comparison table of the incentive schemes in force in different countries, with the range of insolation to be found in that country would be helpful. Oldboltonian 21:48, 26 October 2006 (UTC)

Added intro as suggested by itsmejudith--Oldboltonian 10:47, 25 November 2006 (UTC)

PV Power costs (again)

The table doesn't specify what technology is being examined. I'm assuming since the concern is a terrestrial power grid it would be silicon, but this should be made explicit. Perhaps tables of similar pricing for gallium-arsenide cells would be appropriate, though judginbg by this talk page the table itself appears to be something of a contentious issue. - IstvanWolf 14:50, 2 November 2006 (UTC)

The table is technology independent. Only price per watt is needed to calculate it. --212.202.73.243 21:35, 12 December 2006 (UTC)

Through this whole article are several comparisons with other energy sources, sometimes with financial / economic data. Jonfos has cavalierly pruned the the comparison between costs of heating liquid with mirrors and PV power stations ("distracting"). Such comaprisons seem to me to have their place in this wikipedia article, so I'll put the back.--Oldboltonian 16:36, 26 May 2007 (UTC)

Japan

Somewhere, prolly in HomePower, I read that world prices were going up because of incentive systems in Germany and Japan. I see the Germany here. If I find a bunch of Japanese stuff, should I put it under the other countries? Japan is not only a large producer of panels (Kyocera for the win), but also they are users (dunno how they compare to Germany for amounts). Sadly, I'm in Europe and my beloved HPs are in the US... and I won't get them shipped here until June-ish 2007. 82.93.133.130 10:26, 30 November 2006 (UTC)

It's hard to say if you should put it straight in or not without knowing what you are likely to find. You might want to bear in mind that while sources not in English are acceptable in English Wikipedia, English-language sources are to be preferred if possible. There seems to be a lot to say about the economics of PV and perhaps we should think about a spin-off article at some point. Itsmejudith 14:04, 30 November 2006 (UTC)

PV module prices are tracked by solarbuzz [10], and you can see they have risen. As demand exceeds supply, prices are controlled by the feed-in tariffs. Modules are sold for the highest price that still offers the investor about a 7 year return on investment. Since Spain and Italy Greece and France in Europe, and California and Korea have added FITs. Japan has no more incentive system, but it has very high grid prices.--Oldboltonian 07:13, 2 December 2006 (UTC)

Spain

Since the financial incentives section for germany, greece, california... does a distinction between intallations above and below 100 kWp, and since the spanish legal framework does the same, i think it should be included in the article. According to Royal Decree RD436/2004, the feed-in tariffs are as follows:

first 25 years:

• Installations <= 100 kWp: 575% of the TMR = 0.4404 EUR/kWh
• Installations > 100 kWp: 300% of the TMR = 0.2289 EUR/kWh

Installations >25 years:

• Installations <= 100 kWp: 460% of the TMR = 0.3523 EUR/kWh
• Installations > 100 kWp: 240% of the TMR = 0.1838 EUR/kWh

TMR: Reference Mean Tariff (Tarifa Media de Referencia) TMR as at 2006 = 0.076588 EUR/kWh. A new TMR is fixed by the government each year. Source here (in spanish, sorry)

Also, the article says that the contract duration is 25 years. That's incorrect, contracts have a different selling price for the first 25 years, but they don't have a fixed duration.

Problem is, nobody is installing more than 100 kWp in spain: As legal framework is much better for small instalations this means that if, for example, you are building a 1000 Kwp installation, you set up 10 independent 100kWp installations, each one owned by different individuals. The installations can share panels and land, but they can't share lines and transformers: large istallations have a building with rows of 100KVA tranformers, instead of a single transformer, what would be much more efficient. I don't know how the situation is at other countries, but this makes the price for >100kWp irrelevant, since nobody is using it.

I don't have much experience with wikipedia so i prefer to add the info here and have one of you to move to the article page is you find it suitable. —The preceding unsigned comment was added by 81.44.77.96 (talk) 15:13, 6 December 2006 (UTC). Tidied and incorporated. We're agog to see what the Spanish government to come with. Presumably the 100kW cap will be removed--Oldboltonian 16:32, 26 May 2007 (UTC)

Efficiency

This article could do with some analysis of the improvements in efficiency (and the related issue of decreased lifespan). For example, the article [11] mentions 40% efficiency, but I've heard from the South African research that this comes at a cost of decreased robustness. Greenman 09:50, 8 December 2006 (UTC)

PV power stations

The following sentence is pretty speculative:

But as all industrialised nations share a need for electricity, it is clear that solar power will increasingly be used to supply a cheap, reliable electricity supply.

This is not at all clear. There are good reasons for being skeptical about how widely the current technology will be deployed (cost), and what benefits it would have (relatively low EROI). However, I think something like this sentence, qualified as a projection rather than fact, would be good for the introduction to this section. Can someone find a study that gives some projections of future PV energy production? CyborgTosser (Only half the battle) 10:03, 3 February 2007 (UTC)

Solar tracking

I feel that the following part is too ambiguous, especially about declination versus east-west tracking. I also think that semiyearly adjustment is fairly common, especially in non-equatorial regions. So, I replaced:

This implies that the orientation of the panel should be optimized for the latitude at which it is used. (In theory the orientation can be changed from hour to hour or, more practically, from month to month, but this is rarely done.)

with:

Panels are usually mounted at an angle based on latitude, and often they are adjusted seasonally to meet the changing solar declination. Solar tracking can also be utilized to access even more perpendicular sunlight, thereby raising the total energy output.

Thank you, --LRG 23:13, 18 February 2007 (UTC) I don't know of too much seasonal adjustment happening in Europe. I think panels are almost invariably fixed (except trackers)--Oldboltonian 21:27, 11 May 2007 (UTC)

EROEI

The section on energy returned for energy invested has some silly text in it. There's a reference to some random article by some random person named Jeff Vail. Vail's argument is poorly argued. Using his methodology, you come to the conclusion that Oil has an EROEI of 1:1. I think the whole concept of EROEI is silly since you can't actually rigorously define how much energy is invested. In any event, EROEI doesn't matter. What matters is whether or not you can make a profit installing photovoltaics and selling the generated electricity, or installing photovoltaics and not paying for grid electricity. Cesium62 00:36, 15 March 2007 (UTC)

I've taken the liberty of removing the argument in question. It assumes the price of an installed PV system is representative of the energy used, which by no means is true, and there is no sense in comparing EROI using this abnormal methodology with the standard methodologies.Jens Nielsen 07:28, 16 March 2007 (UTC)

Worldwide installed photovoltaic totals

Can anyone provide a source for the claims inthe section on Worldwide installed photovoltaic totals, specifically the one claiming total worldwide capacity at more than 5 GW and the 90% share of the three leading countries? The best sources I can find [12], [13] show lower figures (though lagging two years behind). Also, the IEA figures seem to include only figures for selected countries, so I wonder what it says for the global total. Jens Nielsen 13:10, 16 March 2007 (UTC)

Data just published by Eurobserv'er for EU countries

Installed PV Power as of the end of 2006 source Eurobserv'er' / SEIA /

Country	PV Capacity (MWp)
	Cumulative			Installed in 2006
	Off grid	On grid	Total	Off grid	On grid	Total
Japan
Germany	32	3 031	3 063	1 150	3	1 153
United States	275	340	615	60	100	160
Australia
Spain	15	103	118	1	59	60
Italy	13	45	58	0	11	11
Netherlands	5	46	51	0	0	0

Spring 2007

Given that this is an international project, maybe it would be better to avoid using the seasons to denote dates. (The Northern Spring is the Southern Autumn, etc)

Ordinary Person 03:58, 7 April 2007 (UTC)

How about performance against production cost/ shoping cost ?

I know wiki isn't Ebay, but about every month there are solar panel breaktroughs it seams. So how about a list, based on a year of average sun hours how good they perform per square meter and their production cost/shop cost. I know production cost is hard to get, so therefore shoping cost as a high average for it. This toptic is a sugestion, it's not about payback, but it is about technolgy and it's performance.

Biased Numbers

There seems to be a pervasive bias among proponents of solar power to quote biased numbers in their favor. There is a great deal of intentional confusion between peak output and actual output from solar panels. There are numerous errors in this and other articles about solar power. It is dishonest to compare the peak output of a solar panel with the peak output of other means of generating power because solar by its nature actually generates only a small percentage of its maximum possible output. Not only is there darkness for half the average day, but also the graphs of actual energy generated for solar panels look like pointed curves with a peak around noon and minimal generation a few hours later. To compare a PV plant with a peak output of say 10 MW with a conventional power plant of peak output of 10 MW is dishonest. The real outputs in these cases will be more like 1.5 MW for the solar plant to 8.5 for the conventional plant. But then to compare the prices of a 10MW solar plant to a 10 MW conventional plant is doubly dishonest when the real outputs are not even discussed. And how can this be explained if it is not a deliberate attempt to make solar power seem much more viable economically and as a source of energy than it truely is? Openman 06:13, 21 April 2007 (UTC)

Are you suggesting that the article should be changed and if so, in what way? Itsmejudith 12:02, 21 April 2007 (UTC)

It is pertinent to compare the cost per kWh of electricity produced, the so called 'levelized cost of electricity' in which investment is depreciated over a certain time, and operating costs are taken into account, divided by power output to give the cost per unit of energy.

Feel free to add some objective data on this, although it would be better placed in an article covering more sources of energy than PV.

It is perhaps unfortunate that PV has grown up measuring the efficiency of its modules by exposing them to a standard radiation source, and that measurement (so called kWp has now become the unit by which the PV industry measures its production capacity of modules. I doubt the scientists who devised this methodology did so in order to put PV in a good light v other sources of electricity.

I don't see the 'intentional confusion', 'numerous errors', comparison of the price of a 10MW conventional power plant with a 10MW solar plant etc.

--Oldboltonian 12:24, 29 April 2007 (UTC)

How is it any more "dishonest" than comparing a 500 MW coal generator to a 500 MW nuclear generator? After all, the coal generator will produce, on average, 10-20% less energy than the nuclear generator. A 500 MW natural gas generator will produce, on average, less than a quarter as much as the coal generator. In fact, a well designed PV plant in a location like Arizona will produce just as much energy per MW as the average natural gas turbine in the United States (both have roughly 20% capacity factor). The United States has 383 GW in natural gas generating capacity and 313 GW in coal generating capacity, yet coal produces 50% of the nation's electricity and natural gas just 19%. Furthermore, the energy from a 500 MW coal generator will be cheaper than that from a 500 MW nuclear generator, which will be cheaper than that from a 500 MW natural gas generator, which will be cheaper than that from a 500 MW PV generator. I understand Openman's point, but the rated capacity of a generator is not a proxy for the amount of energy it can be expected to produce or its economic viability, no matter the generation technology. For fossil fuel technologies it is a proxy for the amount of energy you could produce in theory, but that's not very meaningful. So when a utility installs a new generator someplace and says "this generator can supply electricity to 10,000 homes," knowing full well that while it might do so under certain conditions, on average it will not do so -- well, that description fits most generators installed by utilities these days. Why is describing PV that way less honest than describing other generators that way?--Squirmymcphee 17:40, 28 June 2007 (UTC)

The appropriate choice of unit depends on what you want to compare. The installed capacity in MW is a fast and convenient way to compare the power of different facilities, in fact it's a standard measure in the tech world. Open a technical magazine with the section on newly built plants, and I'll bet you'll see capacity measured in MW, no matter if it's a coal plant, nuclear, PV, or whatever. But granted, the number of MW is not a good measure at all of how much fossil fuel-fired capacity can be replaced by a PV plant, and it would be no bad idea to mention the issue of MW/MWp comparability somewhere, at least in a footnote. Jens Nielsen 19:04, 28 June 2007 (UTC)

This is clearly an important subject, and apparently an emotive one, but does a comparison of the yields of different types of energy generation belong specifically on the PV page. MW capacity per se is not the end of the story, it goes back to economics. So I'd say WP needs an article on the economics of power generation. It would fit will into the stub called Comparison of power plants and a detailed article linked therefrom on the cost of nuclear. --Oldboltonian 05:58, 29 June 2007 (UTC)

Companies

Not sure who started this section but it needs a lot of expansion, if it is to be reasonably complete, and probably merits a wikipedia entry of its own. 1. Key companies are missing, such as market leaders Sharp. Shell went out of PV 2 years ago. 2. Distinctions will need to be drawn between the different activities in the PV chain: silicon, wafer, cell, module, installation, operation.--Oldboltonian 12:30, 29 April 2007 (UTC)

Sharp Solar has its own page now, which can be referred to. And there is also a List of photovoltaics companies now, which can also be referred to. I've changed the section heading to Major photovoltaics companies, as clearly there is a limit to the number of companies which can be discussed here without swamping the whole article. In terms of different activities in the PV chain etc., I would suggest that this could be the subject of a new article, perhaps entitled Photovoltaics commercialization.

PS Oldboltonian, when are you going to start your User page? :) -- Johnfos 23:37, 1 June 2007 (UTC)

Out of the bushes now ;)

Commercialization is bit vague. The Photovoltaics article should be the overarching article that summarizes and relates the existing articles about silicon, PV cells, PV modules (a stub I just started), BIPV and solar roofs (these need to be merged, gloabilzed and expanded) PV arrays (which is 90% not about arrays, and needs to be merged into PV). Installation and operation is also enough material for an article and could absorb some of the financial incentives information. The detailed data on incentives could also go to short article leaving only highlights in the main PV article. I need to reread the procedure for exporting part of an article into a new one and maintaining the relevant history.--Oldboltonian 18:42, 4 June 2007 (UTC)

I've put in my 2 cents over on Talk:Photovoltaic_array. Basically, I think PV modules should redirect to PV arrays, although the distinction is pretty insignificant, and I don't have any vested interest in which title sticks. We just don't need two pages for what's really the same thing, it's confusing. Indeterminate 04:03, 10 July 2007 (UTC)

Modules are not the same as arrays. An article on PV modules should discuss their construction, differences between manufacturers, efficiency, use cases, etc. and an article on arrays should cover different types of arrays, mounting systems, sizing of strings of modules etc. There is plenty of to say about both topics. I'll try to edit the articles a bit to reflect this in the next week or so. Merphant 06:56, 10 July 2007 (UTC)

Opening paragraphs

The first introductory paragraph and the first "Current developments" paragraph are the same. Should one of them be deleted or changed? 154.20.151.165 03:39, 8 May 2007 (UTC)

Have made some changes to the lead section now, so it better complies with WP:LEAD. -- Johnfos 04:37, 8 May 2007 (UTC)

Africa and India

Individual household photovoltaic units are the thing in Africa and India, made in East Asia, and I don't see it in the article. --McTrixie/Mr Accountable 16:11, 4 June 2007 (UTC)

Probably worth a paragraph or two .... are the systems delivered as kits or do you need to source components separately. Reasons not to use the grid (there isn't one?). Cost, satisfaction, how are they paid for....

There isn't one would be the most obvious reason. Today copper gets ripped up and sold on the scrap market as fast as new wires are run, frustrating the electrification and landline markets in the developing world. The table of Installed PV Power has columns for off-grid and on-grid. On-grid has the enormous advantage that you get to use the grid as your storage battery for night time and cloudy days. 199.125.109.54 19:42, 7 June 2007 (UTC)

Most appropriate would be to kick off an article about Off-grid PV. Add sections on Australia, EU, NA and there would be a decent article. Go for it!--Oldboltonian 18:50, 4 June 2007 (UTC)

Solar shingles

Can someone import this image from http://www1.eere.energy.gov/solar/photovoltaics.html ? It's a great photo. There is another one somewhere on the site showing a carpenter using a hammer, but carpenters don't use hammers any more, they use nail guns, like in the above photo. 199.125.109.57 03:08, 13 June 2007 (UTC)

The photo is OK to my mind, not particularly great. Carpenters use a variety of tools including hammers. Itsmejudith 12:12, 15 June 2007 (UTC)

Wp

Explanation of what is Wp has been edited out of main section. Since the comparison of nominal power of PV attracts lots of interest from those wishing to compare the merits of one form of generation v another, I suggest we keep an explanation in the article.--Oldboltonian 23:39, 16 June 2007 (UTC)

Certainly. I did a minor correction and added a good reference that mentions the standard test conditions and why they aren't necessarily realistic. Dicklyon 23:53, 16 June 2007 (UTC)

The main reason saying it isn't realistic is not relevent to the article is because it is what it is, and when a 154 MWp array is installed in one country it should be obvious that if the same array was installed in a location with half the solar insolation, the Wp for that installation would be half. In other words no one is going to take the manufacturers rating of a single solar cell and just multiply it by the number of cells in the array to come up with the MWp rating of the array. A discussion of Wp rating of a single solar cell is much more appropriate in the solar cell article. In this article I am hoping that 154 MWp means a real 154 MW at the brightest best time of day and on the best day of the year for that installation. 199.125.109.13 19:07, 17 June 2007 (UTC)

Too bad, that's not what it means. Maybe you can find a source for the actual situated peak power, and add that, too. Dicklyon 22:52, 17 June 2007 (UTC)

Huh? Did you have a different definition of Wp in mind? For example, the 250 KWp array recently installed in Rwanda, are you trying to say that it would be 250 KWp only if it was installed in the US, but is actually 300 KWp because it is installed in Rwanda? I don't think so. 199.125.109.113 00:56, 18 June 2007 (UTC)

Huh? Did you read the article or the reference? kWp is kWp no matter where it is. The actual peak power output, however, will vary, depending on the amount of sun, etc. Dicklyon 01:07, 18 June 2007 (UTC)

Agreed that the article needs a brief explanation of the meaning of Wp. Ideally it would be drawn from a source. An academic paper would be ideal of course, or a perhaps a user's guide to PV, failing that, perhaps from the website of one of the major manufacturers. Itsmejudith 21:52, 17 June 2007 (UTC)

That was done yesterday. Please take a look and see if it needs work still. Dicklyon 22:52, 17 June 2007 (UTC)

Let's look at some of the references. From http://www.solarsystems.com.au/HCPV_Technology.html we have 154 MWp which is expected to generate 270,000 MWh per year. If we use the figure 365.24 days per year we find that works out to a capacity factor of 20%, pretty close to the 19% which is quoted in the article. If we look at http://www.pvresources.com/en/top50pv.php we have lots of examples.

Solarpark Gut Erlasee 12 MW 14,000 MWh 13% Huerta Solar Milagro 9.51 MW 14,000 MWh 17% Solarpark Mühlhausen 6.3 MW 6750 MWh 12% Solarpark "Rote Jahne" 6 MW 5700 MWh 11% Bürstadt plant 5 MW 4500 MWh 10% Solarpark Leipziger Land 5 MW 5000 MWh 11% Springerville Generating Station 4.59 MW 7732 MWh 19% Solarpark Geiseltalsee/Merseburg 4 MW 3400 MWh 10% Solarpark Zeche Göttelborn (part one) 4 MW 8200 MWh 23%

From http://www.investinportugal.pt/MCMSAPI/HomePage/NewsRoom/The+world+s+largest+photovoltaic+power+plant+in+Moura++Portugal.htm 62 MWp 88 GWh, or 16%

From http://www.juwi.de/international/information/press/PR_Solar_Power_Plant_Brandis_2007_02_eng.pdf 40 MW 40,000 MWh or 11%

The three references for that 19% capacity factor number are http://www.juwi.de/international/information/press/PR_Solar_Power_Plant_Brandis_2007_02_eng.pdf which gives 18.8% for solar power http://www.utilipoint.com/issuealert/print.asp?id=1728 which states typically less than 25% for solar I have seen another reference that gives 20%. The BP Solar reference has apparently been moved.

Everyone states that the capacity factor depends on the amount of sun. No one says anything about Wp being measured under standard conditions. The point that I am trying to make is that as an engineer if someone asks me to design an individual solar module, I am going to rate it under standard conditions because I have no way of knowing where or how it is going to be used. On the other hand if someone asks me to cover their building with solar panels and ask me what the peak output power is, there is no way that I am going to use the standard conditions value. You might be able to get away with doing that for a small user, but not with a large installation.

Here is a better example of what I am talking about. California has a program called the California Solar Initiative as part of the Million Solar Roofs program, if your installation is 100 KW or less you can get paid $2.50/watt (decreasing about 7% a year) based on expected system performance, calculated based on equipment ratings and installation factors, such as geographic location, tilt, orientation and shading.[14] In essence, Wp depends on if you are buying modules or selling power. One is calculated using standard conditions, the other using real conditions for you.199.125.109.113 01:54, 18 June 2007 (UTC)

Anonymous user, you are confusing what you feel would be a logical definition of Wp (as you describe it) and what the industry calls Wp which is in fact nominal power. When a module comes out of the factory, be it in Germany, China or California it is necessary to measure the nominal power to measure production capacity.

Now, when the modules are installed, comes the yield. This obviously depends on the insolation, and the same module performs differently in California and Germany with a different yield. You can argue about the PV industry's choice of words, but those are the words the industry has chosen. It is appropriate however for WP to interpret those words for the reader.--Oldboltonian 21:03, 25 June 2007 (UTC)

my first edit of May 26 was not so bad Photovoltaic power capacity is measured in Wp (Watt peak). In spite of its name, 'peak power' is in fact a nominal power value. It is the measured power under so called 'Standard Test Conditions' [15]. These artificial conditions, developed for standardisation and comparison of different solar cells or modules. They do not correspond to real life conditions, and in particular do not represent the peak power available of the cell or the module during highest sun exposure.--Oldboltonian 21:14, 25 June 2007 (UTC)

I looked to see if the description of Wp in the article is OK, as Dicklyon suggested. It may be adequate, certainly there is a good source for the initial point. However, a problem with the structuring of the article is apparent. There is even some duplication of wording. To my mind the description of what PV actually is is far too mixed up throughout with the economics questions. The effect is that someone who wants to establish what PV (e.g how it differs from solar water heating) is immediately confronted with points that actually belong to a discussion about investment and payback. Could we agree to restructure so it is science first, economics afterwards? Itsmejudith 09:55, 18 June 2007 (UTC)

I agree that article needs some major restructuring. I'd propose that the article becomes an overview (ie a set of summaries) of cells, modules, applications, systems, and then some economics, statistics and politics. The cell article is good, the module a stub, systems and applications do not exist.

For comparison, here's how the German article is structured.

• 1 history of the Photovoltaik
• 2 technical description
• 3 achievement
• 4 efficiency
• 5 potential
• 6 Grid parity
• 7 integration into grid 7,1 fluctuation of the offer o 7,2 conformity to consumption o 7,3 transmission o 7,4 storage o 7,5 supply security
• 8 costs o 8,1 investments
• 9 current production costs o 9,1 general o 9,2 comparison with conventional production over the assignment area + 9.2.1 1. Current production costs in the first operational year + 9.2.2 2. Current production costs in the elften operational year + 9.2.3 3. Current production costs in the twentieth operational year + 9.2.4 4. Current production costs in the twenty-first operational year o 9,3 comparison over financing expenses and irradiation o of 9,4 module prices o 9,5 current situation of the price history o 9,6 feeding remuneration
• 10 installations, export rates and manufacturers leading world-wide

--Oldboltonian 21:03, 25 June 2007 (UTC)

The capacity factor should be changed back to 20% from 19% because using 19% implies that the capacity factor is known to two significant digits. And 20% is the most widely used rule of thumb capacity factor, not 19%.— Preceding unsigned comment added by 208.54.94.32 (talk) 18:31, 17 July 2007

19% was used because that is what the reference said it was. That number was also for the US, so it may be different in other locations. Actually the capacity factor is known to better than two digits, except that it is not a constant. 199.125.109.18 04:04, 9 August 2007 (UTC)

"[The capacity factor] is not a constant." Right, it's a rule of thumb for PV solar, and it's 20%. I think I'll change it to 19.357% just to be cynical. "The worldwide average capacity factor for PV is approximately 20%." --www.crest.org/repp_pubs/articles/pv/5/footnotes.html cleanenergyfunds.org/library/ca/CEC_wiser_solar_estimates_0205.pdf www.divpower.com/pv_commercial.htm signing is silly67.58.254.68 10:12, 28 September 2007 (UTC)

Solar power station

This is not a new idea. I remember hearing about it being rejected 20 years ago - the alignment of the beam drifts off and "whoops there goes Detroit". The fact that power available at the planet surface from solar is hundreds of times current usage makes the concept unnecessary. 199.125.109.113 04:18, 18 June 2007 (UTC)

I think you can tell that I am voting for the deletion of this silliness. The article Space elevator economics (which begins with a massive red question mark questioning the accuracy of the article) states that it currently costs $20,000/kg to launch into geosynchronous orbit (and it seems likely that would be where these beasts would be located), and you still have to have an energy receiving station on the earth, i.e. either a PV array or microwave receiver, so the question is, is it more practical to put your concentrator array in space or on the ground. If there was a severe shortage of land available on the ground of course it would be in space. Since there is a vast amount of land available (BPsolar estimates that an area 200 miles on a side is sufficient), I think the issue is definitely moot. Not to mention the affor mentioned launch costs. Right now I am waiting to hear what the folks who wasted their time going to the seminar concluded. 199.125.109.136 21:32, 18 June 2007 (UTC)

Are you proposing to delete the WP article Solar power satellite on the basis that it is "silly", ie will never be economically viable for earth use? Surely the appropriate treatment is to comment that the idea has been mooted, but that is is unlikely ever to be implemented because of cost of launch and provide the link--Oldboltonian 20:42, 25 June 2007 (UTC)

Being "silly" is not grounds for deleting the article. Being "moot" is not grounds for deletion, however it should not be given any undue creedance. The concept has been brought up and mooted before and will likely be mooted each time it comes up. Having an article that explains that it is silly is good. Making links to it? What for? Do we need to make links to everything that does not work? 199.125.109.64 21:07, 10 July 2007 (UTC)

Business-side info

I had previously added a link to a global directory of PV manufacturers (http://www.enf.cn). The information was taken down by someone who hadn't actually reviewed the validity of the information but was deleting based on the fact that I posted up several links to ENF.

I would like to request that another editor review the relevance of the following link:

• ENF Ltd PV Market Research and Industry Directory

And resubmit it if it is considered useful to those people looking up photovoltaic information. Please also consider putting a mention under the section that talks about PV companies (since the ENF site has a directory of 3000 PV companies).

Kit Temple 13:46, 2 July 2007 (UTC)

Linkspam is a sensitive issue on this page, but if we are to include any commercial sites this one could be one of the most useful. Itsmejudith 18:46, 17 July 2007 (UTC)

Merger proposal

I proposed merging Photovoltaics in transport into this article. That article seems to have little point and adds nothing of substance to the encyclopedia. It appears to be a convenient place to drop links to various other specific PV powered or PV supplimented vehicles and so it appears to be just a list of vehicles that have this tangential connection of having a PV panel somewhere on or near the vehicle. Maybe the list is too axiomatic for me in that it seems obvious that any vehicle that uses electricity CAN have that electricity supplied by a PV. I used to have one of those solar powered window fans in my car that would pull air out of the car to help keep it cooler. That alone seems to qualify my 1965 Chevy Malibu for the Photovoltaics in transport article.

I propose creating a few short paragraphs with links to general areas where PV is used and few, if any, links to specific vehicles. Maybe something like this:

Photovoltaic power is used in many forms of transport either for motive power or as auxiliary power. Solar energy is often used to supply energy for satellites and spacecraft operating in the inner solar system. In aviation, no commercial use has yet been found for photovoltaics, although there is considerable military and scientific interest in solar powered unmanned aerial vehicles (UAVs). Many experimental and demonstration solar planes have been built.

The area of photovoltaic modules required to power a car with design and performance similar to an internal combustion car is very large, so for propulsion, it makes more sense to generate electricity in a stationary system and power the car from rechargable batteries. Nevertheless many prototype solar cars have been built, especially for challenges. Small solar-powered electric boats have been in use for several decades. On rails, photovoltaic panels were tested as auxilary power on Italian rolling stock under an EU project. Photovoltaics are also integrated into alternative transport concepts such as PRT

I think the subject deserves less, but I don't see why photovoltaics in transport would require more than this. --JJLatWiki 17:47, 10 September 2007 (UTC)

• Oppose merger. I think there is probably going to be enough material to merit a sub-article, although it's a good idea to keep everything concise and to have a good couple of paragraphs in this article. Your suggestion above is good in many ways, but still rather under-referenced. We would need a reference, for example for the first sentence of the second paragraph, as this is partly a matter of opinion. And without a reference, there could be doubt about the definition of "alternative transport concepts". Itsmejudith 15:04, 11 September 2007 (UTC)

• • Thank you. I should have mentioned that I primarily summarized the existing photovoltaics in transport article and made no effort to gather references that were not there or significantly evaluate the verifiability. I was focusing on form over function. If that info is in doubt, I'm all for striking it. However, if the photovoltaics in transport article is pared down to these 2 paragraphs, it becomes a tiny stub that is already less likely to be patrolled and so will continue to collect dust-bunnies and parasites. If it's tiny, why does it deserve its own article? --JJLatWiki 15:54, 11 September 2007 (UTC)

My response is that, even when cut down, the PV in transport article is usefully divided into different sections, which can potentially carry detail that would be too long to include here. And even if there's not much to say about each section, the technical issues around applying PV to very different modes of transport, from spacecraft to bicycles, are so very different as to merit description under such headings. I'm sure that there is enough published in reliable sources, in academic journals even, to yield a sentence or two about PV in each of those contexts. Itsmejudith 16:10, 11 September 2007 (UTC)

Merge tag has been removed per discussion. 199.125.109.113 01:43, 15 September 2007 (UTC)

Advantage and Disadvantages

I moved some material from the Solar Power article over here. I don't mean to dump it but the material all applied to PV. This section has seen a lot of ranting over on the Solar Power page but there does seem to be some merit in presenting both the advatages and limitations of photovoltaics. —Preceding unsigned comment added by Mrshaba (talk • contribs) 17:53, 11 September 2007 (UTC)

PV Installed Worldwide

In the Glittering Future of Solar Power [16] I found this Merrill Lynch report [17] that give some numbers for PV production in 2006 and an estimate for 2007. These are production numbers vice installation numbers so I don't know if you want to use this source in the lead but mentioning these estimates in the body seems appropriate.

The table here seems like it should be in megawatts rather than kilowatts. What is the idea for having capacity per capita? Having a column of estimated PV electricity generated is another idea. Also, what is meant by 14 - 224 kWp/capita is recommended? This is a very large range of recommendation. 14 - 56 kW·h/capita also seems like a large range. I could not find these numbers in the sources listed? Mrshaba 08:15, 20 September 2007 (UTC)

It's an old table. We switched from kW to MW because the numbers got a lot bigger the next year. Note that there are still a lot of small numbers in the 2006 data. I see no reason to go back and redo the old table. When more 2006 data becomes available and 2007 data we can just ditch the old table. As to where the column about per capita came from you would have to ask the person who added it. They went through a lot of work to add it so they must have gotten it from somewhere. As to the "Glittering" article, it's really just a blog, and a comment says that it says the same thing that T. Bradford does in the book "Solar Revolution". The price graph is interesting, though,[18] showing that PV electricity will be down to about $0.04/kWh in the near future. The Merrill Lynch paper can certainly be referenced, I have seen it before so it may be used already somewhere in a reference (solar power ref #38). However, it is a monthly article, and it is dated April, 2007. Where are the more recent issues? 199.125.109.136 05:14, 24 September 2007 (UTC)

I didn't see anything in Bradford's book that was as interesting as the Glittering blog. I've done several searches for 2006 and 2007 installed capacity. The Lynch paper is the best I've found to date.

The table I was talking about seems to have disappeared. I don't know where it went. The only improvement to the current table that I would suggest is the addition of a world cummulative total. I figure someone has already requested that. Mrshaba 06:29, 28 September 2007 (UTC)

I shifted the 2005 table out to deployment of solar energy to grids: the role of the photovoltaics page is to contain the highlights of the detailed articles not every excruciating detail down to the negligible amount of PV installed in Lithuania, which IS recorded in the appropriate place.--Oldboltonian 18:44, 5 October 2007 (UTC)

@Mrshaba, I am the guy (appearing exceedingly foolish at present) who added all of the 'Total kWp/capita' data to the 2005 table (from the 2005-table-listed-reference, it was good enough for the reference, why not wikipedia?). But the estimate for the recommendation (from the estimated consumption rate) is the purpose of this prose. I deliberately left the range of values very large (upper limit 4 x the lower limit for overall use, and 16 x lower limit for peak power capacity as the sun shines with sinusoidal power over only half the day) as it was only an estimate based on what I could remember at the time, and I fully intended for someone like yourself to come along, be exceedingly critical (as your comment illustrates) to the point of looking for ACTUALLY DECLARED consumption rates (possibly on a country by country basis) and correct my estimate (which was intended at the time for only industrialized countries, like my own). I was mostly influenced by a graph I remember stumbling upon (for some country X, the name escapes me), which stated that if residential zone consumption per person was one unit, then commercial zone use would be another unit, industrial two more units, and mass transit one more unit (5 units total per person, even if they worked from home & never traveled, this aggregate formula was stated to apply nevertheless, due to that persons indirect consumption of energy through that of manufactured goods and other energy using services). Then I checked the power rating for a common PC power supply, which was given as 0.45 kW, plus a common monitor 0.176 kW for 0.626 kW, times the 24 hours per day that most people leave them on for = 15.024 kW.h/day, rounded down to 14 kW.h/capita.day for lower limit, x 4 for upper limit (I considered x5, but I didn't want to seem like an insanely energy intensive consumer). At the time, these numbers seemed to be a very conservative estimate (due to my excluding many other forms of energy use). Then, Oldboltonian deleted all that I had triple-checked & written (upon reading this talk page I fully understand and agree with his decision & reasoning), but this caused me to read the above linked document from the EU: EU - 25 retail electricity prices which specifies in a footnote, and I quote: "The household prices presented here are based on a household consuming 3 500 kWh of electricity annually, of which 1 300 kWh at night.". Assuming that their "standard household" houses 4.2 people (2 parents + 2.2 kids) each, that would put consumption at 2.28 kW.h/capita.day. (It also specifies standard industrial annual consumption rate being 571.4 times that of households, but I have no way of knowing their population per "standard industrial energy supply contract".) I only mention this as I still believe that this data of kWp/capita & kW.h/capita.day (on a country by country basis) are essential items for people to know, in determining how much of their grid's energy is clean (and therefore acceptable for them to use)(I might add an on-grid percentage column to make this clear), and whether or not to install an On-Grid or Off-Grid setup for their own home or business, with a clear understanding of how much capacity they will consume Off-grid, or how much demand there will be for their clean product On-grid. BTW, Mrshaba, I fully intended to add data for World (for which I currently see from the current table as:Off-grid=566.626, On-Grid=5,110.378, Total=5,679.264 MWp), and groups like EU and maybe even OECD vs. non-OECD (but all this talk of deleting my work shortly after it's tabulated has taken the wind out of my drive (slight renewable energy pun intended)). If anyone has disagreements, or further comments, feel free to voice them (either here or at my user page directly). 202.168.102.96 04:49, 16 October 2007 (UTC)

I would recommend adding the column, but leaving off any comments about "suggested amount". 199.125.109.89 03:38, 18 October 2007 (UTC)

I was constructively critical Anon. Your table can be improved by including a tighter and more grounded band of electricity use. Here are some per capita numbers that you could use: [19] A band of about 7,500-10,000 kWh/year is a decent value. I've read there is a electricity consumption level above which quality of life does not significantly improve. I'll look for that number if you wish to use it. This source indicates quality of life does not significantly improve above about 4,000 kWh/year:[20] This number is close to the lower end of the band you chose. I would say this is a good relative number for the lower end of the band. You multiplied this by five to include nearly all the industrial countries. How about using a band of 4,000 to 10,000 kWh/year? I see the source did have a Watts per capita column but I don't see this information as adding much value. The information also complicates the table because going forward the table would have to be recalibrated for both population fluctuations and growth of PV. The electricity can also be used outside of national boundaries so this introduces another complication. These are all suggestions. Mrshaba 17:21, 20 October 2007 (UTC)

The colors in the right column of the table are a very nice addition. I still question the Wp/capita info. This might be true information but how does it help understanding? I've never seen this metric used for other energy sources. Have others? Mrshaba 05:41, 4 November 2007 (UTC)

I looked around at some of the other energy articles and I never saw output divided by population. There are however subtle differences between the energy sources which require that they incorporate different data in their deployment tables so I'm not suggestion that the Wp/capita info needs to go. After thinking about it, I would say there is merit in developing a standard table template for comparing the various energy sources in a bare bones way. Is there a place on WP where I could place this suggestion and help work on it. Mrshaba 09:31, 5 November 2007 (UTC)

Korea 2006 data

IEA PVPS report filled the gaps for AUs and japan - anyone got data for korea 2006?--Oldboltonian 21:32, 25 September 2007 (UTC)

It was in the same report, unless you meant DPRK. 199.125.109.136 14:53, 1 October 2007 (UTC)

PV. Reader unfriendly, unnecessary abbreviation

"PV" is a reader unfriendly, unnecessary abbreviation. It should not be used. --SmokeyJoe 07:32, 27 October 2007 (UTC)

That horse has already left the barn -- "PV" has been a common abbreviation for photovoltaics for at least 40 years, and you'll find it used in nearly all writing on the subject.---- Squirmymcphee (talk) 18:27, 16 November 2007 (UTC)

Economics

Just ran into this article. Reading through this talk page, there is a good amount of discussion about the possibility of spinning off a PV economics article. As it stands, there's already an economics section in the current article (which is mostly OR). Either way, there may (or may not) be interest in referencing this tool developed by myself and an actuarial student:

Photovoltaics Economics Calculator

It's validated against PVWatts, which is a widely recognized tool for determining how much power you'll get in different parts of the country. All of the formulae used are visible in the (linked) source code, and most reference published papers on their use or show their derivations.

Anyways, I'm not going to add it to the article, as that'd be a conflict of interest on my part, as well as self publishing. However, if anyone else thinks its worth adding, feel free. It might at least help make it so the economics section has verifiable formulae and references behind it, or make for a useful "external link". -- 129.255.93.189 22:46, 1 November 2007 (UTC)

PV production and prices

Not sure where to post this message so it's going in several places. The PV articles would be greatly enhanced if we could develope a graph showing the historic prices for PV. The image below shows how the prices should be both real and inflation adjusted. As a companion to the price graph we also need a production graph.

Mrshaba 09:31, 5 November 2007 (UTC)

See Figures 3 and 4 in [21]. They're a little old, but I'm certain I've seen more recent charts in other publications by the same author -- I just don't have time for a more thorough search right now. If you have a little time you might also search for the DOE's multi-year program plan and check some of the publications at [22]. The raw data you need for such a chart, unfortunately, come almost exclusively from very expensive off-line sources (though for production data I do remember somebody spamming this talk page with a site that purported to have that awhile back...).---- Squirmymcphee (talk) 18:54, 16 November 2007 (UTC)

I know what you mean about off-line sources. I contacted Robert Margolis at NREL and asked for his data but he hasn't gotten back to me. Tear... Nobody wants to play with me. I'll keep trying. Mrshaba (talk) 02:51, 21 November 2007 (UTC)

This a a rough draft of a PV price vs PV production history. Any suggestions or requests on how to present this info. I can easily pull the production off the graph and just compare $/Watt in real and inflation adjusted prices or compare price against cummulative installed PV.

Left Y axis is a log scale $/Watt. Right Y axis is log scale Megawatts. Red boxes represent inflation adjusted $/Watt. Blue diamonds are real $/Watt. Green triangles represent production in megawatts.

I've made several other graphs from Maycock's info. The graphs and the table they are derived from are here:User:Mrshaba/Experiments#PV Graph. Check it out. Mrshaba (talk) 17:35, 10 December 2007 (UTC)

It is more conventional to plot price as a function of cumulative production on a log-log scale. I'm not saying that you have to do it that way, but it makes the relationship between price and production much more clearly than what you have here, in my opinion. Also, a slight correction to your economic terminology: costs expressed in "real" dollars are inflation-adjusted, while those expressed in "current" or "nominal" dollars are not. So in your chart, red boxes represent real $/watt and blue diamonds nominal $/watt.--Squirmymcphee (talk) 21:22, 10 December 2007 (UTC)

OK... Thanks for correcting my terminology. I was more worried about keeping prices and costs straight. When I talked to Maycock I asked whether the numbers were inflation adjusted but I might have misinterpreted his answer. The information seems correct in it's current form but I might have to redo the inflation adjustment. Does it look right to you Squirmy?

I can set up a graph of price vs production but I don't see any need to put prices on a log scale. I'd rather chop off pre-1981 data and have everything in nominal dollars or pre-1986 data and have both nominal and real dollars vs production. What do you think of this? Mrshaba (talk) 18:42, 12 December 2007 (UTC)

The inflation adjustment looks to me about like it usually does for Maycock's numbers (his numbers are a little higher than those from other sources in the mid- to late-'70s time frame). The reason both price and production are typically plotted on log scales is that when they're plotted this way you get a relatively straight line which is important in the learning curve theory of price reduction. Linear-linear and log-linear plots of the data tend to leave the impression that prices are stable, not declining, since the same decline in price now occurs over a much larger increment of cumulative production than in did in, say, 1983. But plot the data both ways and see what you think.--Squirmymcphee (talk) 20:19, 12 December 2007 (UTC)

I'm familiar with learning curves but they should plot cost against production rather than price against production. This is especially true because prices and costs are decoupled for PV. You really have to tailor your window to get the PV data to behave according to the learning curve models. Don't you agree?

I did find Maycock's numbers a little high when I compared them against Perlin's numbers. I asked Perlin to clear this up and he said he got his data from Dr. Berman so I wrote to Dr. Berman hoping he can give me some price and production numbers for the early 70s. What other sources of data are you comparing against Maycock's numbers. Are they on the net? Any chance you could send them me? Mrshaba

I'm speaking primary from having seen similar charts with attributions other than Maycock. The most commonly cited figures for that time period seem to come from a consulting company called Strategies Unlimited. To my knowledge, they are not available online and are very expensive to purchase -- I have only ever seen them indirectly. There's a white paper by a guy named (Christopher?) Harmon that I believe you will find online that uses these data -- if you can find the paper (which I no longer have) then you can probably ask him to share the data. There is also a guy named W. G. J. H. M. van Sark in the Department of Science, Technology, and Society at Utrecht University who will soon be publishing a paper on experience curves and cobbled together a decent data set. Hope that helps.--Squirmymcphee (talk) 21:47, 12 December 2007 (UTC)

Thanks for the leads. 71.103.233.189 (talk) 22:30, 12 December 2007 (UTC)

Installed Photovoltaic Power as of the end of 2006

This table has gotten unbelievably complex. Do we really need all these columns? 199.125.109.89 02:52, 6 November 2007 (UTC)

Clarification (or merge) needed

Clarification or Merge needed

Wikipedia has an article "Solar cell" as well as the article "Photovoltaics", and these two cover rather overlapping ground without a clear rationale for which article has what material; plus an article Photovoltaic array which covers related ground from a different perspective. "Solar cell" and "photovoltaics" should be either merged, or else rewritten so that the difference between the two subjects is clear. Geoffrey.landis (talk) 20:42, 27 November 2007 (UTC)

There was some kind of consensus that Solar cell would carry the basic science of the PV effect, while Photovoltaics should be about the technological field, in terms of both research and applications. Very small scale technology, such as solar cells in electronic calculators, can probably stay in the Solar cell article. Photovoltaic array had a different origin, as you can see. One of the reasons that it exists is to carry the distinction between "solar panel" as a PV module and "solar panel" as a solar thermal panel. If you feel the division of labour between articles is still inconsistent, please move material around. Itsmejudith (talk) 16:07, 28 November 2007 (UTC)

---

someone has edited the home page (defaced it)? maybe should be locked or protected? 192.160.130.38 (talk) 02:54, 28 November 2007 (UTC)

Not necessary. Most vandalism gets fixed very quickly, and it is important to Wikipedia that "anyone can edit". The vandalism edit you spotted was what is called a "test" edit. Thanks for noticing it and fixing it, and welcome to Wikipedia. When you edit any article it says in bold please do not save test edits, but as you can see not everyone pays attention. 199.125.109.113 (talk) 01:31, 30 November 2007 (UTC)

Disadvantages

The disadvantages section is rather small and contains several understatements. It says:

• Solar electricity can sometimes be more expensive than electricity generated by other sources.
• Solar electricity is not available at night and may be less available due to weather conditions (solar panels generated reduced amounts of power in some types of inclement weather;) therefore, a storage or complementary power system is required.

The first point says sometimes, I'm not really sure when it's actually cheaper. Does anyone have any examples? It's usually significantly more expensive then most other sources. The second point says that a storage system is required, but this does not state that such systems are also very expensive and further reduces solar's efficiency and effectiveness. Let me know what you think. Thanks!

Codingmonkey (talk) 05:15, 5 December 2007 (UTC)

The primary example of a situation where PV is cheaper than conventional electricity is in an off-grid situation where a grid extension would be required to receive grid power. The cost of a grid extension can exceed $50,000/mile and is borne by the customer requesting it, not the utility, so a PV system can easily be cheaper. You can argue that, say, a diesel generator is even cheaper, but if you're talking about an unattended commercial installation (a cell phone tower, a radio beacon, etc.) then you have to pay somebody to go refuel it periodically if you use a generator (and depending on the site's location, that may be dangerous or impossible at certain times of year).

There are also certain areas, both in the US and outside of it, where the retail price of electricity is high enough for PV to be competitive, if not cheaper. For a residential user in California, for example, each kWh beyond a certain number in a month costs well over $0.30 -- it is cheaper to generate those kWh with PV than to pay retail, even without California's generous subsidies. There are also isolated rural areas in the US -- primarily on small islands -- where PV is competitive with retail, if not cheaper. Another good example is Japan, which has high enough electric rates that PV is economically competitive in many areas.

In the end, for most of us in the industrialized world PV is currently more expensive than conventional electricity, often significantly so, but I think to say that it is sometimes cheaper is accurate without having to resort to hard-to-find special cases -- tens, if not hundreds, of millions of people experience the situations I described (though most of them are probably outside of the United States).

As for the second part of your comment, I'm not sure what you mean by storage systems reducing solar's effectiveness -- a properly designed system will be as effective as you need it to be. It does reduce overall system efficiency, particularly if you're drawing from the storage system regularly, and it drastically increases the cost of a kWh. However, to my knowledge it is quite common to choose self-generation (be it PV with storage, diesel generator, or something else) over the grid extension for grid extensions beyond a quarter mile or so.--Squirmymcphee (talk) 15:16, 5 December 2007 (UTC)

You need to include the costs of global warming in the cost of the existing electricity supply. When you add that in, solar is far cheaper everywhere. 199.125.109.134 (talk) 05:57, 6 December 2007 (UTC)

This is an argument from environmental economics and may be notable. Can you help us find a source that makes this argument specifically in relation to PV? Itsmejudith (talk) 11:53, 6 December 2007 (UTC)

Standalone Devices, confusing?

"PV has been used for many years to power calculators and novelty devices. Improvements in battery technology made it possible to power a calculator for several years between battery changes, making solar calculators less attractive. In contrast, solar powered remote fixed devices have seen increasing use recently, due to increasing cost of labour for connection of mains electricity or a regular maintenance programme. In particular, parking meters [58], emergency telephones [59], and temporary traffic signs." What? Improvements make it less attractive? Is this minor vandalism? —Preceding unsigned comment added by Frazz (talk • contribs) 18:31, 6 December 2007 (UTC)

Well, I fixed it. However, I'm not sure it's right. All I did was make it logically sensible. And fix the British spelling. (Frazz (talk) 15:54, 7 December 2007 (UTC))

Installed power

We obviously still need to resolve the wording for installed power in the Worldwide installed power section. Wp from the manufacturer is simply a standard rating for the panel that means how many panels you bought. Installed power means the peak power you expect to get out of those panels, which depends on, did you install them on the north side of the roof or on the south side? Did you use a tracking system? How much average insolation is there in your region? All of these and many more factors determine the rated output power of your solar panels. I couldn't care less how much Wp is shipped, I want to know what the maximum watts you are going to get out of your solar panels, which is why Installed power is not the same as nominal Wp. If you are using a single axis tracking system, you get 30% more Installed peak power, and another 6% if you use a dual axis tracking system. It takes twice as many panels in Norway to get the same peak power as it does in Spain. The Wp you have to buy for one MegaWatt installed power in Norway is twice as much as the Wp you have to buy to build a one MegaWatt installed power plant in Spain. In the worldwide installed PV, I don't care how much Wp it took, I want to know what the output rating is, and the table should show only installed peak output power, not how much silicon it took to get that power. Look at the Nellis Solar Power Plant for example. They are apparently using 70,000 215 Watt panels, and are using a single axis tracking system, so their power rating is not 15 Megawatts, but 18 Megawatts. We really need to add an additional column that states how much energy was generated for the year, in GW-hrs, as well. 199.125.109.41 (talk) 06:29, 7 December 2007 (UTC)

You are confounding the size of a power plant with its capacity factor. Your point is valid, but it is by no means unique to PV and proper terminology to deal with it has been well established in the electric power industry for decades. A power plant's capacity denotes one thing and one thing only: the amount of power it produces when running at maximum output. This means that installed power equals the manufacturer's rating for the generator, be it a nuclear, coal, hydro, wind, or PV generator. It is not an indication of the amount of energy it will produce over a given length of time, nor is it intended to be. Capacity factor is the indicator of the amount of energy produced, and it reflects how the generator is used (which is typically, though not always, governed by plant economics), how much downtime it incurs for routine and unscheduled maintenance, plant safety, quality of system design, availability of fuel. Capacity factors tend to be strongly correlated with plant type, but can also depend on geography, weather, politics, and other factors. Nuclear power plants in the US average capacity factors around 90%, but some do better and some do much worse. Coal plants are around 75-80%, but again, some do better and some worse. Non-tracking PV plants average around 15-20%, and natural gas plants (in the US, at least) average less than 20%. In fact, the US actually has more natural gas capacity installed than coal capacity, but generates 2.5 times more electricity from coal. So you can see that power plant size alone is not really a very good indicator of the amount of energy it will produce for any type of power plant. Just as a 100 MW coal plant might produce twice as much energy as a 100 MW natural gas plant, a 100 MW PV system in Spain might produce twice the energy of a 100 MW PV system in Norway -- but they're all still defined as 100 MW systems.

As for the article, I think comparisons of PV capacity factors to other energy technologies would be appropriate. Is that the sort of thing you have in mind? I suspect that altering the installed power numbers themselves would qualify as original research, unless you can come up with some solid references to back it up, and that is prohibited in Wikipedia.--Squirmymcphee (talk) 22:36, 10 December 2007 (UTC)

I neglected to mention that various adjustments to the way solar panels are rated have been proposed over the years, but none of them have caught on. These generally aim to provide consumer-friendly information about energy yield in addition to the peak power rating, but they've all been problematic in one way or another. It may be worth mentioning in the article that these efforts exist, but since none has any support I'm not sure it would be appropriate to discuss any specific proposals in-depth.--Squirmymcphee (talk) 17:24, 12 December 2007 (UTC)

General style and structure

Amateurism

After I read first 4 lines of the article, I was convinced I wouldn't find the answer to how PV arrays work. This is whats wrong with most of Wikipedia articles. For some reason there aren't any details on Wikipedia. I want to be able to build if I choose to a PV array, not hear just about economic deals! Teemu Ruskeepää (talk) 21:17, 13 December 2007 (UTC)

Yep, the intro needs work but don't throw the baby out with the bathwater. Mrshaba (talk) 01:07, 14 December 2007 (UTC)

China's 1.5GWp plant

From the article: "The three leading countries (Japan, Germany and the USA) represent 90% of the total worldwide PV installations. China is building a 1.5 GWp PV plant, though.[19]"

This is misleading. 1.5GWp is the capacity (yearly output) of the plant (from the source), and should not be classed with 'PV installations', as they are different things. Gresszilla (talk) 09:59, 15 December 2007 (UTC)