Talk:Photovoltaics/Archive 2

Lengthwave
I think it may be nice to have some graphics or data about the energy corresponding to each wavelength in the energy recieved in the surface and the energy used in the photovoltaic cells. —Preceding unsigned comment added by 85.81.171.82 (talk) 19:16, 21 January 2008 (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 €/kWp. The costs for customers are much higher cause the firms must grow very fast. Take a look at the german article too Fotovoltaik there's much more information about photovoltaic. The calculation is the following for 3,000$/kWp, 2000 kWh/year, 4% interest and 1% cost of operation: Money costs: 3000$ * 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€/kWp 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€/kWp. But 1,200€/kWp are silicon costs cause we use chip silicon at the moment. Now the production uses solar silicon which is about 70€/kWp. So in the near future production prices could be lowerd to 1,000€/kWp 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€/kWp at ebay: (scroll down to the middle of the page). If you pay 15,000 € per kWp better ship your modules from germany.--212.202.193.176 11:37, 8 August 2006 (UTC)
 * Here is an auction for 7.26 kWp .--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$/kWp. Now the auction ends at 4422 Euro/kWp. It includes all, modules, inverter, cables and mountings for self-construction. So in Sicily (1800kWh/year) you can produce power for 24 eurocent/kWh. Net power costs are 21.08 eurocent/kWh. Here you can buy modules for 3,49$/Wp  and thin film ones for 3$/Wp.

$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)
 * Excel

Here is another calculation from diablosolar: --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 (kWp), of a PV installation. The headings across the top refer to the annual energy output expected from each installed kWp. 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)

Further comment on: "With lifetimes of such systems of at least 30 years" from a retired electronic engineer. I first noticed that there is no citation for this figure. While stating that capitol equipment lasts 20 years is just a rule of thumb, to state 30 years should be footnoted. There are other issues to consider here.
 * Silicon devices don't last forever. This applies both to the cells themselves which would suffer some degradation in performance due to annealing and passivisation failure and to the semiconductors in the inverter.  Power transistors do suffer catastrophic failure.  Maintenance costs would increase with time and replacement costs would become significant.  MOSFETs are more reliable than Bipolar transistors and reliability continues to improve, but it is something that should be considered.
 * It should also be considered that a system installed today would probably be obsolete in 10 years. This would probably mean that major repairs would not be possible and/or would be not be economically justified.

In general, these are the issues faced by all early adopters of a new technology. Yet some early adoption is needed to push the technology. Tyrerj (talk) 02:26, 3 January 2008 (UTC)


 * I should be able to find a citation for the 30-year figure. It really applies to the PV modules, not necessarily to the whole PV system, and it is based on accelerated lifetime testing -- the modules made 30 years ago didn't really have 30 year lifetimes (though quite a few of them are still in operation). The cells themselves are well encapsulated and don't see much in the way of thermal or electrical stress, and cells removed from decades-old modules have mostly been found to work as well as they did the day they were produced. The primary degradation mechanism for PV modules is UV and thermally induced degradation of the EVA encapsulant used as a pottant to secure the solar cells in the module. Even so, mean times to failure for PV modules from published field studies are between about 500 years and 7000 years (which doesn't mean a module can be expected to last thousands of years, but that in a given year you can expect a few hundredths of a percent of modules to fail -- the failure rate will increase near the module's end of life). While nobody can claim the cells will last forever, they are very likely the longest-lasting component of a PV system (and by a longshot). Individual modules can be replaced without having to replace the entire system, and the typical PV module warranty is 20 years and guarantees no more than 1% degradation per year. I think some of this is covered in the solar cell article.
 * The inverter is another story. It is, in fact, the shortest-lived component of the system, though it is primarily a result of capacitor failure rather than failure of the power semiconductors (which are primarily IGBTs these days). However, the inverter can be repaired, and even if it is not economical to do so it can be replaced independently of the rest of the system at a small fraction of the cost to replace the entire system (it currently represents about 10% of the installed system cost).
 * Given all of this, obsolesence isn't really much of an issue. Few systems will have to replace even one module in the course of 10 years, and though many will have to replace the inverter in that time it is a relatively inexpensive repair compared to replacing the entire system. If the system is still producing enough energy to meet one's needs, there is no reason to scrap it. And if it isn't, one can always add a few modules to bump up its energy production. I'm not trying to say that there are no issues with the technology -- there most certainly are -- but I think you're picking on the wrong ones.--Squirmymcphee (talk) 03:05, 3 January 2008 (UTC)

I can offer the following:

"These attributes have led the National Renewable Energy Laboratory in Golden, Colorado to recognize CdTe’s potential for achieving the lowest production costs among current thin film technologies. (Photon International, November 2004, page 50). CdTe module costs well below $1.00/Wp have been predicted by NREL and others." http://www.firstsolar.com/company_technology.php

"PART I  Item 1:     Business   We design and manufacture solar modules using a proprietary thin film semiconductor technology that has allowed us to reduce our average solar module manufacturing costs to among the lowest in the world. In 2007, our average manufacturing costs were $1.23 per watt, which we believe is significantly less than those of traditional crystalline silicon solar module manufacturers. " http://investor.firstsolar.com/secfiling.cfm?filingID=950153-08-367

""During the fourth quarter of 2007 we benefited from the full capacity and economies of scale of our Frankfurt/Oder plant. This combined with continued throughput and conversion efficiency gains afforded us strong operating leverage and decreased our manufacturing cost per watt by 12% year over year to $1.12 per watt in the fourth quarter of 2007, further solidifying our cost leadership position in the industry," said Michael J. Ahearn, Chief Executive Officer of First Solar." http://investor.firstsolar.com/releasedetail.cfm?ReleaseID=294090

Regards, —Preceding unsigned comment added by 189.136.158.209 (talk) 22:01, 10 April 2008 (UTC)

By the way, I don't have the data, but I would find it extremely valuable to see a visual chart of average cost of PV in dollars per watt per year. For instance, a chart showing average cost per watt from 1970 to the present. This would perhaps show a declining cost from the past to the present.

Regards,

Eric —Preceding unsigned comment added by 189.136.158.209 (talk) 22:09, 10 April 2008 (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, 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

The current numbers are extremely misleading. First of all, they are based on cumulative production, not actual installed capacity. Secondly, they are based on the peak output values of the cells, now care to have a guess how likely it is for all cells across the globe to peak their production at once? Thirdly, the capacity factor of the cells are typically in the 17%-30% range at best, so the 12.5 GW figure is not in any way accurate. Photovoltaic never produce that amount of electricity no matter how you count.The only way you would get that output was if you put all cells in one place and measured it at its peak value. To put into perspective how bad teh figure is. According to IEA and OECD figures the production during 2005 was 840GWh giving a time-averaged output of about 0.1 GW, now it has increased since then, but not by more than 100 times. At the very least the introduction ought to specify that those are peak-values, to simply state the 12.5 GW figure is highly misleading at best, an outright lie at worst. Heck, even the source for the statement claims "12,400 megawatts, enough to power 2.4 million U.S. homes" which makes it clear they are talking about peak output and not average output. I'd say we stick to the IEA and OECD figures. They may be lagging by a year or two, but they are more reliable than the garbage that is currently used. 85.224.219.135 (talk) 11:20, 21 January 2008 (UTC)


 * To specify peak capacity in this manner is consistent with the way the electric power industry specifies the size of any power plant, be it PV or otherwise. The generation capacity figures for two power plants are never directly comparable without knowledge of the capacity factor, particularly if the two plants rely on different fuels. In the US, for example, natural gas is responsible for 40% of generation capacity but only 20% of actual electricity production, while for coal those figures are about 30% and 50%, respectively. I discuss this at greater length in response to another comment below. Don't get me wrong, I'm all for providing a realistic indication of the amount of energy produced by PV, but to use the generation capacity figure for that is garbage regardless of what generating technology you're talking about.--Squirmymcphee (talk) 19:22, 21 January 2008 (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)

Hmm... I'm having difficulty resisting the impulse to delete the table and its explanation under Economics of PV. Basically, there are many unexplained details: Why are some cells green or red... or more confusingly yellow? I presume these are weighed against current U.S. electricity prices, but from what source? I'm not sure if this is really valuable, considering it doesn't look to include non-PV module costs (or has an overly optimistic view of what PV costs). If this is merely an exercise to show how to calculate the economics of PV, then I propose that a separate page be created that runs through the process of calculating PV economics. Anyway, I'll give it a few days and see if the original poster or anyone else wants to tweak/explain the table before I ax it, since it does look like it took quite a bit of work to create. :-) PandasCanFry (talk) 04:28, 22 January 2008 (UTC) Also, economical by what standards? Grid parity? If so, by what source?  Another issue is that economical versus non-economical is very EASILY changed by toying with interest rates, depreciation calculations (straight-line versus MACRS), etc.; so without reasons for using the initial values, what useful conclusions can be drawn from this table? I DO think that the table is valuable, but without anything to substantiate the initial conditions, it's original research at best and conjecture/wrong at worst. The other tables in this article are verifiable, but the conclusions that result from reading this table are not. Again, I think this is better suited on a separate page that describes calculating the economics of PV. Finally, I've also never heard of the kWh/kWp as a unit of insolation, but I'm not discounting that people use this as it's much more convenient then kWh/m^2PandasCanFry (talk) 15:40, 23 January 2008 (UTC)
 * All the table is, is a straight forward calculation of installed cost divided by insolation to get average kWh cost. There is nothing magic about it. The gradation of colors shows the trend from expensive to economical. Once again nothing special. Using three colors instead of two creates more of a gradient, while more colors is not necessary to see the effect. It's a pretty useful graphic and should not be deleted. The 20 years in the corner cell was confusing, so I have removed it and added a title. 199.125.109.124 (talk) 20:01, 22 January 2008 (UTC)
 * I am confused by the units of insolation. I expected watts per meter-squared, or some similar measure of capacity per unit area. What I read in the table makes no sense at all -- or am I missing something here? BTW, please register with Wikipedia, it will give us a better way to communicate with you, and it will give your contributions more weight with other editors. — Aetheling (talk) 00:30, 23 January 2008 (UTC)
 * It's a standard measure, but since you asked the question it clearly needs to be explained better. The units are given in the table, kWh/kWpyr, same as the far right column in the "Produced, Installed & Total Photovoltaic Peak Power Capacity" table. What you do is take the insolation number in kWh/kWpy and multiply it by your panels kWp to get your kWh/year. Couldn't be a simpler calculation. So let's say you install a 4 kWp panel and your insolation is 1000, you can expect to get 4,000 kWh each year. The insolation is a number that is averaged over a year, and is independent of the efficiency of the panel, because it is given in kWh/kWpy, and not in watts/meter-square which is also a measure of insolation but if you use that you have to determine the efficiency of your panel to find out what your output will be. Take a look at the article insolation and see what we need to change either there or here to make things less confusing. Just as an added wrinkle, if you add tracking to your panels it adds about 30% to your annual output. The easiest way to accommodate that is to add the 30% to your rated Wp but this is not universally recognized. Looking at the insolation article I see that it needs work as it confuses irradiance with insolation. 199.125.109.124 (talk) 05:01, 23 January 2008 (UTC)
 * In my experience, calculations on the economics of any energy system get quite complex. I'm not quite sure what is meant by "assuming a 10% capital cost."  Does that means an initial loan for 90% of the system? More importantly, why these parameters?
 * I'm sure the 10% capital cost is meant to refer to the effective rate of interest paid on capital, but by and large I agree with you -- at the very least, the assumptions used in the calculations must be spelled out much more explicitly. How you do the calculations properly and what assumptions you make vary considerably depending on who's paying for the system and how they can/will pay for it. The cost to a homeowner paying with an ordinary loan is higher than for a homeowner paying with a mortgage or home equity loan, and those are both much higher than the cost to a business that gets tax credits for capital investment and depreciation. Plus, I see no mention of inflation and discount rates, both of which are important when you're talking about cash flows over a period of decades. The numbers shown in the table do seem reasonably consistent with properly done calculations for a residential PV system, but I've seen a lot of improperly done calculations that nonetheless look about right.
 * I've never seen kWh/kWp used as a measure of insolation either. Strictly speaking it is not a measure of insolation, though it is proportional enough to insolation that it can reasonably serve as a surrogate. It expresses the energy obtained from a solar panel as a function of its rated peak output (e.g., if a panel produces 2000 kWh/kWp each year and is is rated at 100 Wp, you would expect annual energy output of 200 kWh). It is meant to level the playing field when comparing modules that have different power conversion efficiencies, but that respond differently to environmental factors like temperature and the spectral content of incident light. It is common that one module will produce 1800 kWh/kWp/year and another 1700 kWh/kWp/year under the same insolation.
 * Finally, the table really only shows the contribution of the solar panel itself to the cost of electricity. The table caption properly indicates this, but it seems to me that the caption and/or the article should indicate that there are other costs associated with PV systems that are not accounted for in the table so readers aren't unintentionally misled.--Squirmymcphee (talk) 18:50, 23 January 2008 (UTC)

<-Working backwards from the definition of Wp, which is a module that will generate 1 Watt with an irradiance of 1000 W/m^2 under standard conditions, and insolation in W/m^2 is the average irradiance, then insolation in kWh/kWp/year = insolation in W/m^2. You will notice that the maps which show insolation in kWh/KWp/year also include a 75% performance ratio to allow for the efficiency of the invertor and specify an optimally inclined panel. 199.125.109.54 (talk) 07:46, 1 February 2008 (UTC)
 * I understand perfectly well where it comes from mathematically, but there are two issues. One is that kWh/kWp does not specify insolation, but the amount of energy you could expect to generate from PV given the local insolation level -- a number that is proportional to insolation, to be sure, but it isn't insolation (unless you assume 100% efficiency). Second, the number of kWh/kWp produced by PV modules under standard conditions doesn't vary from module type to module type, but under real-world conditions it can vary by as much as 20%. These are the reasons I said kWh/kWp is "proportional enough" to insolation to make a reasonable surrogate. As for "noticing from the maps," as I said above I've never seen any such maps -- all the maps I've ever used (or seen, for that matter) specify insolation in units of kW/m^2 or kWh/m^2. Now, it's true that most people ignore the module-to-module variations in kWh/kWp and get close enough in their calculations for most purposes, especially considering annual weather variations, and that's fine, but I fail to see the advantage of adding a level of abstraction between actual insolation figures and the figures that are reported on the insolation map.--Squirmymcphee (talk) 18:12, 3 February 2008 (UTC)
 * It is possible that you are mistaking "your insolation" which is what you would get from a flat panel and "your output" which of course varies by 20%, as you have indicated. Insolation is simply a measure of the average irradiance. It most definitely includes weather variations (cloud cover). It does not take into account temperature variations or mounting considerations, or shading. Wp is calculated under standard conditions, at a specific temperature, and since the output of a panel is a function of temperature, "your output" will not be "your Wp" times "your insolation". Which it probably wouldn't be anyway, because it doesn't include mounting considerations anyway, even if you don't have any shading. Efficiency is not a part of the equation, because it is removed by not specifying panel area, but by specifying Wp, which is a function of efficiency and area, other than efficiency is not a constant, as mentioned. If you want "your output" you have to multiply "your insolation" times "your Wp" times "your correction factor". As I said, in the maps they arbitrarily give 0.75 as "your correction factor". 199.125.109.136 (talk) 16:44, 5 February 2008 (UTC)
 * Okay, I'll start off with a mea culpa of sorts -- above, where I refer to 100% efficiency, is wrong. I didn't think that statement through. In my defense, though, it is also inconsistent with everything else I've been saying.
 * As for the rest, I'm beginning to wonder if you're using conventional definitions for your terms. Insolation is not, as you say, "what you would get from a flat panel," it is the intensity of the sunlight that falls on the panel -- in other words, it is the energy input to the module. It can be expressed in terms of average irradiance, but for the sake of clarity I'll be explicit and say that it is most often it is expressed as instantaneous power (kW/m^2) or instantaneous power integrated over a day, month, or year (kWh/m^2). It is completely independent of the PV module, as the sun shines regardless of whether you place a module in the front of it; therefore, the kWp rating of the PV module is irrelevant and expressing insolation in kWh/kWp is not meaningful.
 * Output, or power and energy production, is "what you would get from a flat panel," and that is what is displayed on your map. --Squirmymcphee (talk) 19:01, 5 February 2008 (UTC)
 * No, the map displays insolation, multiplied by 0.75, and not. 199.125.109.38 (talk) 22:53, 5 February 2008 (UTC)

<--And not what? The (rough) energy output of the panel?--Squirmymcphee (talk) 00:36, 6 February 2008 (UTC)
 * It shows two scales, one is insolation multiplied by 0.75 and the other is insolation not multiplied by 0.75. The first is labeled Solar electricity kWh/kWhy, the second is labeled Global irradiation kW/m^2 per year. See Image:EU-Glob opta presentation.png 199.125.109.38 (talk) 21:17, 6 February 2008 (UTC)
 * So it is precisely as I have been saying it ought to be -- irradiance is shown in kW/m^2 and PV system energy production in kWh/kWp.--Squirmymcphee (talk) 23:01, 6 February 2008 (UTC)
 * To be sure, if insolation is 2000 kWh/m^2 and you assume your modules always operate at the STC efficiency you will calculate an energy output of 2000 kWh/kWp. The insolation and output numbers match, it's only the units that differ, but the units are inconsistent with insolation. Still, strictly speaking you can argue that this makes a perfectly serviceable and useful surrogate for insolation.
 * But then there's the inverter derating factor. The inverter has no impact on insolation whatsoever, unless you use it to shade your modules, so derating for it has no business in an insolation map. On top of that, your implicit assumption that the modules always operate at the STC efficiency is a false one. It's fine for a first-order level of accuracy, particularly with the derating factor you're using, but in the field you will often see low-efficiency amorphous silicon modules produce substantially more kWh/kWp than an identically mounted high-efficiency crystalline silicon module at the same location.
 * I think this discussion has veered off quite a bit from where it started. I now understand where your kWh/kWp number came from, which is why I entered this conversation in the first place. I stand by my original assertion that such a number is roughly proportional to insolation, but it is by definition not insolation. It does, however, appear to be a reasonable first-order estimate of the amount of energy a PV system will produce at a particular point on the map. Related to insolation, yes, but not insolation.--Squirmymcphee (talk) 19:01, 5 February 2008 (UTC)
 * I'm glad to hear that you understand it. The "rough proportionality" is 0.7500000000 (to 10 digits). 199.125.109.38 (talk) 22:53, 5 February 2008 (UTC)

<--Right, I misplaced my "roughly" -- the number on the map is roughly proportional to the amount of energy the system might produce. By the way, where is it that you're finding these maps expressing insolation in kWh/kWp and multiplied by an arbitrary constant? You talk like they're standard tools, but I've been working with insolation maps and data for a very long time and I've never seen one. I'm genuinely curious about who is using them and how. I suppose I can see how they might be convenient for rough sizing of PV systems according to rules of thumb, but they're quite misleading if they're actually labeled as insolation maps while displaying something other than insolation.--Squirmymcphee (talk) 00:36, 6 February 2008 (UTC)
 * In retrospect, I don't think the variation in kWh/kWp between modules of different types is germane to this discussion and unnecessarily complicates it, so I'm dropping it (though it would still be an important consideration in a detail PV system design). It seemed relevant at the time I brought it up, but at that point I thought you were saying something other than what you actually are. So an "insolation map" using units of kWh/kWp displays values that are proportional to insolation by some arbitrary constant, but I still maintain it would be misleading to call such a thing an insolation map. After all, that suggests that if I have zero kWp of PV then it must be dark outside.--Squirmymcphee (talk) 17:09, 6 February 2008 (UTC)
 * Come again? It means that if you have zero kWp installed your kWh will be zero, regardless of your insolation. 199.125.109.38 (talk) 21:17, 6 February 2008 (UTC)
 * Exactly my point. If irradiance is measured in kWh/kWp and you have zero kWp, then irradiance must be zero, no?--Squirmymcphee (talk) 23:01, 6 February 2008 (UTC)

No. Your kWh will also be zero and 0/0 is what is referred to as an indeterminate number - it can be anything. In this case it is your insolation. 199.125.109.136 (talk) 16:33, 8 February 2008 (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 . 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 . 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.

I've made several other graphs from Maycock's info. The graphs and the table they are derived from are here:User:Mrshaba/Experiments. 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?


 * Cost (presuming you mean production cost, as opposed to retail price) vs production would be ideal, but the cost data simply do not exist. Nobody has compiled them, and anybody who has tried has failed because manufacturers simply aren't willing to share that information. The price data used in most of these studies is generally what one would pay for factory-direct orders of large quantities of modules, though, so it's as close to production cost data as you're going to get.--Squirmymcphee (talk) 16:10, 24 January 2008 (UTC)


 * I understand and agree with your points. The thing is, I'm not sure learning curves are all that useful. The cost vs. price issue clouds the picture and there's a lot of data scatter. When I talked to Berman he said he had prices down to $20 per watt in 1972 with production at 20-30 kW. The Hanson report out of Australia corroborates this $20/watt number. This single data point dramatically throws off all the learning curves I've seen. This data point also seriously calls into question Maycock's numbers so I'm doubly stumped. I'm coming to think that this learning curve theory for PV is overly artificial. You have to tailor your window and winnow your data to get a nice price reduction path so I don't see these curves as representative of what's going on or predictive of what will occur. The upshot is - linear graphs presents the data just fine. I think the story of PV is best told by breaking things into time periods and using time-based graphs of price and production. Going forward it would seem that PV prices and costs will continue to skip along. Currently the prices are skipping off subsidies. As these go down PV should eventually start skipping off the grid prices. It will be interesting to see what happens in Italy where they have very high electricity prices, high insolation and relatively local access to suppliers and installers.


 * Also, according to the data Maycock gave me, prices have been rather stable for nearly 20 years. No worries though... The graphs look fine either way and I will have the tabular data available for the curious reader. I tried contacting Harmon but no luck. I'll try van Sark again one of these days. I might challenge him with the Berman data and see what he has to say. We'll see... 64.161.56.5 (talk) 01:38, 26 January 2008 (UTC)


 * You can't really say that data on the industry as a whole is invalid based on information about a single product. The learning curves published for the PV industry are for the PV industry as a whole, and at any given point you're going to find individual products that cost both more and less than the number reported. In other words, I don't think you can claim that a single data point for a particular product throws off the learning curve for the entire industry. It's not a very fine-grained tool, it's meant only to grossly quantify industry trends. There's always somebody ahead of the learning curve, but for anybody to really throw it off track they have to stay ahead of it (and they typically don't, for reasons that are arguably explained by the learning curve itself). There is some value to breaking the learning curve into segments -- there's a paper by a guy named Nemet, if I remember correctly, that does a very good analysis of the learning curve broken into segments over time. I'm not quite sure what you mean by "skipping off subsidies," at least not in the context of the learning curve, but if you're referring to a lack of price reductions in recent years then you are correct, at least indirectly. The prices used for learning curve data are about as close to manufacturing costs as you can reliably get, and the subsidies have increased demand to the point that (a) silicon prices are through the roof, keeping manufacturing costs artificially high, and (b) the PV market is not competitive -- many PV companies barely have sales staffs anymore. Because of those two issues, recent data points have jumped off the learning curve a bit. Some people think this represents a fundamental shift in the learning curve, but there are others who believe this is a temporary departure and that prices will align with the learning curve once again when the market becomes competitive (I'm in the latter category).
 * Maycock's data do show PV prices being relatively stable over the last 20 years, but only if you don't adjust for inflation. Remember, $5/watt 20 years ago translates into about $8.50/watt in 2003 dollars, and that's almost 2.5X current prices.--Squirmymcphee (talk) 22:26, 31 January 2008 (UTC)

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)

Robert Margolis of NREL has a few leads buried in this study:. Nothing past the year 2000 unfortunately. also has some data from PVMaT, which is cost data (not sure if this is public or not), and from Photon International, PiperJaffray and Prometheus Institute market analyses, all of which cost a lot to access :-( However, if someone has these lying around, well, wouldn't that be nice? —Preceding unsigned comment added by PandasCanFry (talk • contribs) 23:16, 23 January 2008 (UTC)
 * There is an interesting comparison of the cost of five of the renewables over the last 25 years at http://www.nrel.gov/analysis/docs/cost_curves_2002.ppt There also is an excellent comparison of cost vs. production showing the learning curve for photovoltaics at http://www1.eere.energy.gov/ba/pba/pdfs/pv_overview.pdf 199.125.109.54 (talk) 04:44, 1 February 2008 (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)
 * It is almost impossible to put a dollar amount on the cost of mass extinction - the earth has had five mass extinctions, and we are in the middle of a sixth. The best known one of course is the extinction of the dinosaurs, but that was not the biggest of the five, and the current rate that we are losing species in this sixth one is perhaps greater than any of the others. I do not expect that we will be one of the species to go, you might be happy to learn. One of the biggest cost increases has been the insurance losses which have been increasing at a staggering rate due to the increase in damages. Once again, how do you attribute a trillion dollars in losses (mostly uninsured) to a specific level of CO2 emissions?  One person asks in a blog, "Do we have any trend data on insurance payouts for weather-related losses? It would be interesting to see if there is an upward trend." Well, duh. 199.125.109.54 (talk) 08:15, 1 February 2008 (UTC)

Capacity factor
25%? Isn't that a tad high? 20% is much more reasonable. Can you supply a reference that gives the capacity factor of photovoltaics? This one shows CF estimates for the United States from 15 to 20%. Since Germany is going to be even lower, I would suggest sticking to 20%, especially when in the next sentence you use 25% to estimate how much electricity is being generated by photovoltaics. 199.125.109.54 (talk) 03:52, 14 February 2008 (UTC)


 * I agree, stating under 25% implies quite a bit for solar, but that (less than)number is a direct quote from the only remaining reference that still works.--202.168.102.96 (talk) 21:42, 15 February 2008 (UTC)

Dealing with Peak Oil
Since the energy watch group proclaimed Peak Oil for 2006, it's interesting how photovoltaic could help to deal with the decreasing oil production. Here my studies about the subject:

How many kWh electric power are necessary to replace 1 litre oil product

How much crude oil can be replaced with 30% or 50% yearly increase of the photovoltaic world market

Extrem fast increase could replace 50 Million Barrel oil a day until 2018 --Pege.founder (talk) 12:43, 2 March 2008 (UTC)
 * Interesting inglish (sic) - "To avoid an oil crisis would be a more fast increase better." I don't see any reason to call 50% a year an extreme fast increase, especially because it does not intercept world energy needs without a huge collapse in energy requirements for 15 or 20 years. Most people don't realize the point that a 50% increase per year takes you from 0.05% to 80% in only 18 years give or take. However if anyone saw the danger facing the U.S. and the world today, a far greater danger than faced at the start of WWII when all U.S. production was stopped and turned into a total war effort to produce tanks, ships, bombs and planes, etc., and a similar "war effort" went into producing wind turbines, photovoltaics and hydrostorage, we could stop criminally burning oil and coal in maybe two or three years - certainly within 5 years, and not miss a beat. 199.125.109.113 (talk) 06:50, 3 March 2008 (UTC)


 * I do not call 50% increase extreme. But there is also a scenario where government pushes the production by 200% a year up, until at last 1000 GW peak yearly production. With this sceanrio, we could replace 50 million barrel crude oil a day until 2018. I see now, I did a mistake at this link, I corrected now this link. --Pege.founder (talk) 12:21, 3 March 2008 (UTC)

PV really replace fossil fuels? Signs not good.
It would be great if PVs could supplant Fossil Fuels and even supply 25% of our energy needs by 2030. However, It appears companies in the industry are minded to produce materials required in far too small quantity to make a difference. I calculate we need 16 million tonnes of polysilicon a year, and adequate PV cell and panel production to match: 2005 Fossil Fuel consumption rate 		1.23E+013	watts Total global energy use rate 2005		1.50E+013	watts Global demand growth rate			2.00% Projected energy use rate 2030			2.46E+013	watts Projected annual energy consumption 2030	2.16E+017	Watt-hours P.A Energy output from 1 watt solar cell		1.20E+003	Watt-hours P.A  Installed PV capacity required to meet 25% of our needs by 2030			4.49E+013	Watts peak Polysilicon required to make PV		8 		grams/watt peak Total polysilicon required if PV will meet 25% of 2030 requirements			3.59E+014	grams Annual polysilicon production required to meet 25% of our needs by 2030		1.63E+013	grams per year Or						16331486.94	Metric tonnes per year

Perhaps the problem is that the management at traditional manufacturers of polysilicon have not had the paradigm shift to imagine production volumes (and the associated economies of scale) necessary to make enough polysilicon to begin to replace fossil fuel. We need new people making and investing in polysilicon production. Both the tool manufacturers and the polysilicon producers are used to making polysilicon on the scale necessary to satisfy manufacturers of semiconductor electronic components. Nick R Hill (talk) 20:55, 5 May 2008 (UTC)


 * Polysilicon production is highly capital-intensive, and it take about two years to bring a polysilicon plant online after ground has been broken. These are the reasons for the shortage in purified silicon right now -- nobody wanted to put up the money for a plant until they were sure the market was there, but once they were sure the market was there it was too late to ensure enough supply. A lot of polysilicon plants are under construction right now -- so many, in fact, that I recently heard of one being canceled because the manufacturer is afraid we'll be in an oversupply situation in a few years.--Squirmymcphee (talk) 15:49, 9 May 2008 (UTC)

From looking at shares sites for manufacturers of polysilicon, it appears to me worldwide production is well under 100,000 tonnes per year. In 2005, worldwide production was 31,280 tonnes. New capacity is coming on-line, which will ease the short-term shortage, and perhaps double the 2005 supply rate. The rate of supply needs to increase to 522x 2005 supply. We need to make as much every 16 hours as was made in the whole of 2005 if PV is to provide just 25% of energy production in 22 years time.

There are other technologies which avoid the use of polycrystalline silicon, but these generally have a much lower conversion ratio so will not necessarily be as competitive and effective as polysilicon based cells, produced in adequate quantities, and at low enough cost, may be. And so far, they have not scaled to take Polysilicon's share of the market.Nick R Hill (talk) 21:20, 5 May 2008 (UTC)
 * One fairly plausible scenario by the Planetary Engineering Group calls for increasing PV production by 200% per year until it reaches 1000 GW/year and then increases by 10%/year. It would reach 100% of current oil energy usage by 2022. At that point production would be 2600 GW per year, which will require 325,000 Metric tonnes per year. All I can say is start shoveling sand. There certainly is no shortage of raw materials, as that is only 203,000 cubic meters, or 0.203 sq. km by 1 meter. Since the Mojave desert is 57,000 km² did I make a mistake or is that a pretty insignificant requirement? I would get started with hydro-storage too, though, as photovoltaics only on average produce full power about 19% of the time, and wind only about 35%, leaving on average somewhere between 54% and 65% of the time with nothing, other than what can be provided from hydro-storage or other storage, such as vehicle-to-grid. 199.125.109.57 (talk) 19:08, 6 May 2008 (UTC)
 * Please remember that the purpose of this talk page is to discuss possible improvements to the article. Thanks. 19:15, 6 May 2008 (UTC)
 * Highly relevant. Relates to the sections on plausibility and growth. I just want someone to check my numbers. 199.125.109.57 (talk) 20:38, 6 May 2008 (UTC)
 * The article strongly suggests to me that PV can replace traditional sources of energy, such as Fossil Fuels. I have published these numerical facts I have pulled together after reading this article (and coming to the false assumption that PV may be on-course to replace fossil) and sharing the figures, to draw to the attention of those editing the page, how very far away from the goal of PV substantially replacing fossil fuels, we, as the human race, are. We can prevent people coming under a misapprehension by pointing out that we will not automatically move towards a PV based economy by making clear: a) how far away from that goal we are, b) how we are nowhere near on target to reach that goal, c) How there doesn't yet appear to be the level of investment and mind-set in the industry and d) what might be necessary for that goal to be realised. I fully accept the goal is technically achieveable, and agree that the idea of replacement of fossil fuel with PV is worthy of serious consideration. A section exploring of the potential for PV to replace fossil fuel, including a discussion of where we are today, and where we need to be, may help focus the mind of the right person for the job to make it so.Nick R Hill (talk)  —Preceding comment was added at 22:29, 6 May 2008 (UTC)
 * Do you have any suggestions for a reference? The purpose of an encyclopedia is to report on subjects using reliable sources, and not to do original research. The fact that we were at 0.04% only four years ago gives me the idea that we are not very close to replacing fossil fuel, although I do like to point out the power of compound interest, which Einstein called the eighth wonder of the world. 199.125.109.57 (talk) 01:09, 7 May 2008 (UTC)
 * World energy usage is based on graph http://en.wikipedia.org/wiki/Image:World_Energy_consumption.png linked from article World_energy_resources_and_consumption. Energy use growth rate obtained by drawing a best-fit line through the graph for the last 10 years to 2005, differentiating, then adding 0.4% to account for the recent spurt of Chinese demand to 17% PA growth. The total figure I had proposed I have found closely matches the International Energy Agency's reference scenario: http://www.iea.org/textbase/country/graphs/weo_2007/Fig01-01.jpg . IEA figure around 17.8 Billion BBL based on Ton_of_oil_equivalent 11,630,000 watt-hours/barrel yielding IEA's estimate of 2.04E+017 watt-hours. My figure is 5.88% higher than IEA's. I am happy to base figures on either. The small difference in these long term projections is immaterial. Polysilicon required per watt is based on calculations based on current SunPower cells which appear to be a technology leader in Polysilicon base cells. A good source of clear reference is: http://www.sunpowercorp.com/Smarter-Solar/The-SunPower-Advantage/~/media/Downloads/smarter_solar/sunpower_dresden_paper.ashx which shows 7.5g/watt with further reductions possible. If you consider wastage (edge trimmings, failures) 8 grams per watt over the period appears sensible to me. The only other variable is how many watt-hours a 1 watt panel will produce in a year. This depends on irradiance. I assume panels will be fitted close to where power will be needed. I have used southern France/northern Spain as a baseline as shown in  http://upload.wikimedia.org/wikipedia/commons/2/28/EU-Glob_opta_presentation.png . That is 1200 watt-hours per year per installed watt peak. I believe every variable I have used in my calculation is sourced, and correlated to within 10%. This is a 22 year projection. Events may unfold over such a period which could affect these figures substantially.Nick R Hill (talk) 22:58, 8 May 2008 (UTC)


 * While the numbers you use in your calculation might we well sourced, where the article is concerned your actual calculations and resulting conclusions constitute original research, which Wikipedia prohibits. Furthermore, if I were peer-reviewing your calculations there are several issues I would raise with your assumptions based on my quick reading (I don't have a lot of time to analyze/discuss this at the moment). First, I think it's a bad idea to extrapolate future growth in energy demand from historical rates of growth. What is the justification for assuming the next 25 years will be the same, plus 0.4%, as the past 10 years? You have the IEA projections, which are very well documented and far more credible than a simple extrapolation -- why not use them?


 * Second, electricity represents something like 15% of our total energy consumption (I'm pulling the numbers from memory, so I might be a little off here and there). Mind you, the primary energy required to generate that electricity is more like 35-40%, but the electricity itself is just 15%, and since PV burns no fuel it is this number and not the primary energy number you need to use for comparison purposes. If PV provides 25% of the world's energy use it will eliminate all of the primary energy required for electricity and leave a huge surplus of electricity to boot. Are you assuming that transportation, heating, and other non-electric uses of fossil fuel will all go electric?


 * Third, polysilicon required per watt has been decreasing at a rate that has only accelerated since the silicon shortage hit. While Sunpower is currently at 7.5 g/watt, they (and the rest of the PV industry) are targeting 5 g/watt in the short- to medium-term. There's no need to add anything additional for waste -- the figure reported already accounts for that (and if it didn't, a mere 0.5 g/watt wouldn't even come close to capturing the true amount of waste). To truly calculate the amount of polysilicon capacity required by 2030 you need to create a time series estimating annual PV production and the number of grams/watt of silicon required in each of those years. That would give you a year-by-year estimate of how polysilicon production needs to grow. If you do it that way, I think you'll find that the magic of compounding ensures that we have many, many years to reach the production level you assert, but that by 2030 we will need much more than you assert. Your figure is simply a 22-year average production rate, and I'm not sure how useful or informative such a figure is.


 * Even then, though, while this is an interesting topic of discussion it isn't something you can include in the article unless you first publish it elsewhere in a manner appropriate for Wikipedia to use as a source.--Squirmymcphee (talk) 15:49, 9 May 2008 (UTC)


 * I accept your overall point that information in Wikipedia needs to be well sourced. (Perhaps I should spend more time slicing positions away rather than arguing unsourced positions...?). You have raised a few questions i'll answer. 1) I had no apriori knowledge of the IEA's figures. It so happens their figures closely match mine. As noted, I am happy to drop my estimate in preference to their figure, which is better sourced than mine. 2) I am working from the principle that electrical energy can be substituted in all non-rural, grid-connected points where fossil fuel would currently be burned to produce heat. Moreover, electrical energy may generally provide a superior replacement for direct burning of fossil fuel, and such situations exceed 10% of today's fossil fuel consumption. (for thoroughness, this would need to be researched, but I don't expect many interested parties would be inclined to question it). Moreover, 25% would represent a proportion of additional demand, therefore little or no replacement of existing point-of-use equipment would be required to exploit an abundance of electrical energy in comparison to fossil fuels.  3) today's price for polysilicon is around $450/Kg vs $23/Kg for 2003. I'd suggest there is extraordinary pressure today on manufacturers of PV cells to reduce consumption of Polysilicon, even if the low-silicon design is non-optimal in other respects. Were the supply of polysilicon eased, you might expect PV cell manufacturers to direct effort towards issues other than minimising polysilicon usage. Another point, which I have not addressed, and poses some difficulty is that PV electricity supply is not available on demand, and depending on climate, may be unpredictable. Air Conditioning demand may tend to match PV production. Other demands would be unaligned with PV production, necessitating complementary power generation and/or storage. You have raised good points. Perhaps this makes a good basis for a peer reviewed article. Can you suggest suitable journals who may be interested?  —Preceding unsigned comment added by Nick R Hill (talk • contribs) 20:35, 9 May 2008 (UTC)

CdTe growth possibility
PV's growth has not been projected accurately in the past and if past is prelude it won't be projected correctly any time soon. You might look into the IEA's and the EIA's track record predicting PV growth. You'll find relatively recent 2020 targets that have already been met. Alternately you can read anything from the 70s for the opposite result. You might learn a lesson from Vaclav Smil who writes convincingly about the perils of projection in Energy at the Crossroads. Or Lovins who writes descriptively about what is absolutely not going to happen in many of his books. My apologies Amory... Just kidding... Two other things: 1) Even without the current "extraordinary pressure" on silicon utilization, PV production and silicon requirements do not move proportionally. Squirmy mentioned this but there's also a report by BP you might look for that gives some numbers. These projections don't factor in CdTe which seems to be a rather disruptive technology. Just a few years ago T.J. Rogers of Sunpower was bragging about how silicon was going to "kick thin-film's butt". Check the earnings statements between Sunpower and Firstsolar and see who's kicking who... And then check back next year. 2) This is also in addition to Squirmy's thoughts on primary vs. secondary energy. A kilowatt-hour (3.6 Megajoules) can push an electric car 5 miles. Using this metric, 10 kWh (36 MJ) can push a car 50 miles. This compares to an efficient car burning a gallon of gasoline equal to 130 MJ. There are no simple linear projections to be made. Once you get out of the protective cover of your conversion tables it's a mess. Mrshaba (talk) 05:15, 10 May 2008 (UTC)


 * I will look for more information from those authors. There have been many announcements over the years of disruptive technology in the PV field. Yet, it appears polysilicon based cells, after decades, in terms of watt-hour produced, dominates. Until I can get a panel which has rolled off (even a small-medium scale) production line, connect a resistor and multimeter across it and wave it towards the sun, I discount the disruptive technology, and I hope anyone else will. These technologies are presented against a backdrop of polysilicon shortage. The raw material for polysilicon solar cells is fundamentally cheap, widely available and of low toxicity. The same cannot be said for Cadmium or Tellurium. Cadmium is poisonous, Tellurium is scarce. More so than Gold or Platinum. One of the 9 rarest elements on earth, the others mostly being radio isotopes. By contrast, Silicon makes 25.7% of the Earth's crust by mass. In terms of accuracy of demand projections, over 22 years, there are many unknowns. Some will lead to energy savings in some areas, others lead to increasing demand. I can't even start to take into consideration other technologies such as reverse electrodialysis which may become cost-effective once the technologies are no longer competing with pumping flexible, burnable fuel from the ground. Nick R Hill (talk) 10:31, 10 May 2008 (UTC)


 * I have carried out calculations on Tellurium availability which show that production of CdTe panels at current efficiency levels will not be much more than 1.5Gw(peak) per year. Using IEA estimate of 2.04e017 watt-hour global consumption for 2030, CdTe panels cannot offer more than 0.02% (or one five thousandth) of global energy demand by 2030 using my above insolation estimate. I will post the calculation on my user page if interested.--Nick R Hill (talk) 16:19, 10 May 2008 (UTC)


 * I agree that silicon dominates but CdTe has made a big splash this last year or so. I don't understand your reasoning for discounting CdTe. I tend to be prejudice towards Si technologies with higher efficiencies but I have to give the other technologies their due. Firstsolar is making and selling a product that works. I've heard FS is producing at nearly half the cost of their nearest competitor. It's true that Te is scarce but there are more things to consider than this. If the demand is high enough you can go after uranium in graphite or sea water. The same can be said of extracting additional Te from zinc or copper. NREL has carried out calculations for CdTe thin films and their estimates go up to 500 GW/year. Mrshaba (talk) 17:11, 10 May 2008 (UTC)


 * I estimate 0.085g of Tellurium is needed to make every watt peak of solar panel based on 11% efficiency and 3 micron thickness of CdTe. http://seekingalpha.com/article/54614-first-solar-vulnerable-to-a-tellurium-shortage suggests 0.135g Te/watt. At my more generous figures, 500Gw/year implies access to 4.25e+10 grams Te/year. 42,500 Metric Tonnes per year. Current Tellurium production is 135Metric Tonnes/Year. According to US Geological Survey, the total world economically extractable Tellurium supply is 47,000MT. http://minerals.usgs.gov/minerals/pubs/commodity/selenium/tellumcs07.pdf . These facts imply that the 500Gw figure is not an annual panel production figure, but is a figure for total possible panel production ever. Given that high demand for Te is likely to drive prices up, CdTe would likely not remain financially competitive with PolySi. Given that there are no raw elemental material constraints for Polysilicon cells, Polysilicon may potentially supply all our needs. CdTe clearly cannot get close. --Nick R Hill (talk) 19:01, 10 May 2008 (UTC)


 * Hmmm...It's NREL's report not mine... They say production past 100 GW/year would face challenges but they also say 500 GW/year is hypothetically achievable.

"For silicon PV technologies, there are no availability limitations at any level of production. But for Cu(In,Ga)Se2 and CdTe, increasing production levels past 100 GW per year could be limited by indium and tellurium availability (see Figure 1). We would need to consider more aggressive extraction for zinc and copper, and more efficient refining methods for these primary ores of tellurium and indium. Developments in supply technology, such as extracting tellurium from manganese nodules on the sea floor, could also ease the potential materials gap. But improvements in PV technology would likely be the main driver: (1) technologies could use thinner layers than those used today, by a factor of 10; (2) materials lost during layer fabrication could be reclaimed and used; and (3) elements such as gallium or aluminum could be substituted for indium. We can also expect additional technological improvements over the next five decades that we cannot currently foresee and that would allow us to reach even 500 GW/yr of production from each of these technologies." Mrshaba (talk) 01:29, 11 May 2008 (UTC)


 * In 2004, NREL optimistically assumed a figure of 0.04665g Tellurium per watt peak. They then optimistically assumed that films of CdTe could further be reduced in thickness by a factor of 10 (bringing Te/Watt down to 4.6mg). They also optimistically assumed Te availability and refining rates 19x Global 2006 levels (USGS 2007). If (and that is a very big if) all these very optimistic assumptions are true (and I haven't seen any evidence to support a single one of them), then CdTe could really be used to make 500Gw/year between 2010 and 2030. That would account for around 5.2% of EIA projected global energy needs by 2030. I very much doubt it, like i'd doubt my neighbour will win the lottery this weekend.. --Nick R Hill (talk) 11:18, 11 May 2008 (UTC)

Based on this very sizeable debate, I think its reasonable to provide a link under See Also to a CdTe PV article SolarUSA (talk) 13:44, 24 October 2008 (UTC) Nevermind - already linked to cadmium telluride photovoltaics SolarUSA (talk) 13:59, 24 October 2008 (UTC)

Perhaps you guys know
This page and the solar energy page have a quote (see below) about PV providing .04% of the TPES. On pg. 3 of the reference provided the term "solar" is described as representing .04% of the TPES but I can't find where it says "solar" is PV only. There could be some concentrating solar or other solar contributors in there. The information as it is currently presented does not seem valid.

"Photovoltaics provided 0.04% of the world's Total Primary Energy Supply (TPES) for the year 2004, increasing by an average of 48 percent each year since 2002, at a rate of growth to reach 0.40% by 2010." 

The 48% growth rate quoted on the page also seems misleading. In 2007, installed PV was about 1000 MW less than the production figure quoted from the Earth Policy Institute. It seems possible that idle production capacity is being counted as production by the EPI people. Both Maycock and Solarbuzz list installation numbers that are 25% lower than this. Mrshaba (talk) 17:43, 6 May 2008 (UTC)


 * "Idle production capacity"? With the demand for product there aren't any idle factories that I know of. The folks I have visited are producing as fast as they can. There is, however always a lead in production vs installation, which accounts for the material that is in the process of being installed and shipped. Marketbuzz quotes a 62% increase in 2007. In installations. "World solar photovoltaic (PV) market installations reached a record high of 2,826 megawatts (MW) in 2007, representing growth of 62% over the previous year." That would make the 48% number highly conservative, no? 199.125.109.57 (talk) 18:03, 6 May 2008 (UTC)


 * Sharp idled about half their production capacity last year due to the constrained poly supply. Many others also idled a portion of their production. As to the 62% growth rate for 2007 you have to compare it against the 19% growth rate Marketbuzz reported for 2006. To be meaninful the page should use data going back to 1997 when growth rates jumped sharply and have since averaged around 35%. The 48% number is not conservative.


 * Page 50 of this source lists PV energy production as 1 TWh (3.6 petajoules) in 2001 when PV installations were around 1 GW worldwide. Page 50 also lists the other solar technologies and if you add them up (206 PJ) and divide this number by worldwide energy use (approximately 471,000 PJ - 2004 number) you come up with the .04% figure from pg. 3 of the IEA ref. The .04% number clearly includes all "solar" inputs and should not be used to describe a PV only contribution to the TPES. Mrshaba (talk) 18:34, 6 May 2008 (UTC)


 * 1997 is a highly artificial year to go back to. Normally people use either the last year available or the last five years to indicate rates of growth. PV has shown an on one year off the next cycle as suppliers catch up with demand. However, it isn't our job to question the accuracy of the sources as much as it is to record them. 199.125.109.57 (talk) 20:44, 6 May 2008 (UTC)


 * The TPES information in the intro is incorrect. The projection based upon this information is also incorrect. Please see pg. 50 of the reference I provided and decide for yourself. Mrshaba (talk) 21:13, 6 May 2008 (UTC)

<=Do you have a number for CSP in 2004? As far as I know there are not many facilities although they tend to be large. All I can account for is less than 400 MW, while 0.039% of 11,059 Mtoe represents an absurdly high number for PV, about 30,137 MWp. The source says they got their numbers from IEA Energy Statistics. 199.125.109.57 (talk) 02:24, 7 May 2008 (UTC)


 * This source has CSP for 2001 . Page fifty. Both then and now the bulk (over 90%) of counted solar energy usage comes from hot water. Mrshaba (talk) 15:42, 7 May 2008 (UTC)
 * Low temperature solar heat is a separate line item, 57 GW in 2001. CSP is 0.4 GW and PV 1.1 GW in 2001. PV installed at the end of 2007 was 12.4 GW. I believe that CSP has not grown as much. I guess I wasn't that far off from 400 MW. 199.125.109.57 (talk) 21:02, 7 May 2008 (UTC)
 * 1.1 in 2001 to 12.4 in 2007 is a 49.7% growth rate. 199.125.109.57 (talk) 21:21, 7 May 2008 (UTC)

Lists
You might consider moving the List of Research institutes and Industry associations to the List of renewable energy organizations page. Mrshaba (talk) 16:27, 9 May 2008 (UTC)

New data
Is this available for 2007? The "Produced, Installed & Total Photovoltaic Peak Power Capacity" table is looking very out of date. 199.125.109.77 (talk) 20:05, 20 May 2008 (UTC)


 * I see that someone put old data into the new table, that is 2006 data into the 2007 table. Even though there never was, to my memory, any 2005 data in the 2006 table.  Did you want new data or not?  Or is this old data, side-by-side the new, simply to emphasize the great difference in market movement (JPN down, all else up & ESP way up)?  (Note: I maintained the old references within the new table so that the sum-total for 2007 = total for 2006 + the installed in 2007.)  If you wanted a table showing the history of installations per annum, or the history of total installed per annum (each of which being two rather different tables, each within my ability as all of the references have already been populated into the 2006 table) then you should request those other tables of me or someone else equally dedicated, while specifying an article-section as their destination(s).  I point-out at this time, that the data used for 2007 installations does not appear to be either official data or comprehensive data, as we are still waiting for the IEA's university participants to finally get around to posting their surveys.  It is for this reason alone, that I will not yet delete the 2006 data from the 2007 table to make room for all of the 2007 data, as the 2007 table has yet to be comprehensively populated.  BTW, the Feed-in Tariff data that I entered was adjusted for 2007 exchange rates from the reference cited, Australia and South Korea are off (the World maximum was adjusted to equal the South Korea maximum (55.84 EU¢/kW·h, not 59.3246 EU¢/kW·h as it was in 2006)), but I'll let someone else try and fix the table until we get our hands on the latest IEA data.--202.168.102.96 (talk) 08:07, 23 May 2008 (UTC)
 * The new table had five columns missing from the old table. In their place, until the full data is available, it was easiest to just add in the 2006 installation data. Showing three years worth of installation data would also be even better. There is definitely a limit to how many columns can be shown - when the on grid/off grid and delta on grid/off grid columns are added the historic data will have to go. 199.125.109.136 (talk) 04:58, 24 May 2008 (UTC)
 * We see that one hour previous to this comment, Kardrak has just made another edit to this article without giving any reasons or consultations to it's wiki-community, this time undoing the edits of many, including but not limited to those we made at the request of this talk-page-section less than 3 weeks ago. This is not the first time this user has made an edit to this article that has needed to be reverted for it's lack of just cause (Exhibit B: Our response to this user's attempt to insert unreferenced data into the table for Mexico: User talk:Kardrak.)  We will not be reverting Kardrak's latest edit, as we are still waiting for the IEA to finally get around to posting the official results for 2007. We recommend either User:Wtmitchell or User:Nigelj be requested to do the reversion, as they made recent edits to the article and seem eminently qualified to make respected changes.--202.168.102.96 (talk) 00:10, 6 June 2008 (UTC)

Merger discussion
A merger discussion has been started regarding the organisation of Photovoltaics, Photovoltaic array, Solar panel, Photovoltaic module, Photovoltaic system and Solar cell. If you would like to contribute to this discussion please click here. GG (talk) 08:20, 25 July 2008 (UTC)

Cosmic ray / Cosmovoltaic panel ?
This is an open theory question for the scientists. Is it possible to build a semiconductor material to convert cosmic rays into electrical current?

Cosmic rays seem to be mostly useless and space agencies spend much of their time building shielding to block it out. Has anyone explored the possibility of making a Cosmovoltaic panel to turn this otherwise harmful energy into useful electrical power? And if so, what would be the proper scientific search term for it, because I have never heard of anything like it. DMahalko (talk) 01:34, 4 October 2008 (UTC)


 * In order to do this the cosmoelectric effect should first be discovered. Further the energy of cosmic ray is so high that it will push the electron on valence band too much and blow up.  The consequence of this is beta-ray-like harmful ray, not electric current. Moreover only 1% of cosmic ray(electron) can transfer energy to the electrons in semiconductor. Yuletide11 (talk) 10:19, 31 January 2009 (UTC)

Photovoltaic power plants
There are many new PV power plants coming online and our List of photovoltaic power stations has gotten rather out of date. Any help with updating would be much appreciated. Also, we need some more individual articles on the larger plants listed. Thanks. Johnfos (talk) 06:04, 12 January 2009 (UTC)

Request for ENF Link
Hello. I would like to request a link to the ENF website: ENF PV Industry Directory (www.enf.cn).

The focus of the website is a Photovoltaic Industry Directory. We have 9 full-time industry research staff and technical staff working on this directory, and a further 16 staff feeding improvements through to the PV directory team. The website now has over 5,000 PV companies listed and published in 7 languages.

I think the website is highly relevant to people looking into the subject of photovoltaics, and I would highly appreciate an appropriate link.

Kit Temple (talk) 03:08, 3 March 2009 (UTC)

Section on the science?
I was wondering if there should be a section on the science behind the panels? I realize that not all types work the same way, but there could be a link to a new page or something that goes over the in-depth theory for all of the types? Pfhortipfhy (talk) 16:51, 29 March 2009 (UTC)


 * I could be wrong, but it seems like this has come up before and the consensus has been that readers looking for information on the science should look at the solar cell, photovoltaic module, and/or photovoltaic system articles for that kind of information. The reasoning, as I recall, is that it is better to write the scientific information once and get all of the editors of that kind of information working in one place than to reproduce it in three or four different articles. There ought to be links to those other articles in this one. If you don't believe it is obvious enough that readers should look in those places then please edit this article as you see fit. That will at least get the ball rolling toward making it clearer.--Squirmymcphee (talk) 10:23, 11 April 2009 (UTC)

Worldwide installed Photovoltaic Totals
I would like to know who produced the table? I think there are some simple changes that can improve it.


 * 1 - get rid of the colors.
 * 2 - get rid of the first zero in the 0800-0950 notation.
 * 3 - round all the numbers to the closest 100 kW. This would lose detail but improve comparison.
 * 4 - To improve readability I added column widths and spacers to the table with these edits: but they have been removed by a troublesome anon with this edit. Perhaps my method of aligning the data can be improved but the idea of aligning the data consistently should be pursued. Mrshaba (talk) 01:47, 30 October 2008 (UTC)
 * 1 - the colours are helpful and should stay.
 * 2 - the first zero was added so that that column will sort properly.
 * 3 - the numbers range from tiny to large so rounding all to one particular value doesn't make any sense - Germany could be rounded to 10 MW, Finland to 10 KW, for example.
 * 4 - the table is way too wide already to make it wider by trying to line it up.


 * What does need to be done to the table, though is fix the ?'s in the ref column, add many additional countries, and check all the references. Who produced the table is not important, it has been in the article for a long time, though updating it each year is a major undertaking, and I thank everyone who has taken the time to do that. 199.125.109.38 (talk) 03:25, 30 October 2008 (UTC)


 * What do the colors mean? There's no explanation for them that I can find. If they're just there for decoration then they need to go.--Squirmymcphee (talk) 22:56, 3 November 2008 (UTC)
 * The colors separate the insolation ranges and make the table much easier to read. They are not there for decoration. 199.125.109.37 (talk) 03:47, 4 December 2008 (UTC)
 * Then the table needs a legend explaining this at the very least, as it is not at all obvious, nor is it obvious which colors represent high insolation and which represent low insolation without a focused effort. And why color this column and not the others? Even knowing what the colors mean I find them distracting, and anything that distracts the viewer from the table's message makes it harder to read. Speaking of which, what is the table's message? It contains an awful lot of information that has nothing to do with the title.--Squirmymcphee (talk) 09:49, 11 April 2009 (UTC)

Also: I think that Insolation is measured in kWh/m²/year rather than kWh/kW peak/year. This value of kWh/kW peak/year does not include any area.... —Preceding unsigned comment added by 194.129.64.35 (talk) 12:00, 7 July 2009 (UTC)

Worldwide installed totals
I believe that this should remain in this article, similar to the table that is in the wind power article. I would point out that the link to history is not a link "to the article where it comes from", but instead is a link "to the article where it goes to". Since solar is much less well funded than wind, the data is greatly delayed - preliminary wind data comes out close to the end of the year and final data around March, whereas with photovoltaics, preliminary data is showing up in March and final data in August. That, however does not make it any less important, and I think it is essential to maintain at least a table of the top countries in the article. Hopefully each year the data will become available sooner than the year before. 199.125.109.80 (talk) 13:08, 27 May 2009 (UTC)


 * The data in the table come from the IEA PVPS; their 2008 review, including quite a bit of country-specific data, has been available since April. You are correct that their "Trends" report, which it appears is where the data in the table come from, will not be out until later in the year. However, the country-specific data are collected only from the nations that participate in the PVPS. This means nations like the Czech Republic, which installed 51 MW last year alone, and Luxembourg, which leads the world in installed PV capacity per capita, do not appear in the table. China, India, Greece, Belgium, and Bulgaria, at a minimum, also have more installed capacity than many of the nations in the table. I think the data are worth having in the article, but should not be presented as a table of the "top countries" in PV installations, at least not as long as the table is based strictly upon the limited IEA PVPS data.--Squirmymcphee (talk) 12:50, 30 May 2009 (UTC)
 * At one time there were as many as a dozen sources for the data in the table, as I recall. It is possible that most of the current table comes from one source, but there is no reason for not adding the Czech Republic if you can find a reference for it, or for Luxembourg, etc. 199.125.109.81 (talk) 02:34, 31 May 2009 (UTC)

Solar calculators
Whoever keeps taking out the solar calculators from the external links, citing WP:EL, please quit it. These are essential external links. 199.125.109.43 (talk) 12:24, 23 June 2009 (UTC)
 * They are sites that exist to link consumers to vendors/installers/whatever, and accordingly are not to be linked per links to be avoided number 14. - MrOllie (talk) 00:18, 25 June 2009 (UTC)
 * Cry me a river that they have a link to installers. There is no reason anyone has to click on the link who does not want to. I never have. It is however the highest rated U.S. solar calculator. Some of the lower rated ones are ones like this one, which I would still use if there was nothing better, as it does provide information for the whole country. 199.125.109.43 (talk) 02:40, 7 July 2009 (UTC)
 * That's another dealer portal, so it won't be suitable either, I'm afraid. - MrOllie (talk) 12:04, 7 July 2009 (UTC)
 * Please be specific about what you are referring to. This, and that, are undefined. If you mean the kyocera calculator, it is a calculator, and yes they have links to a list of or to a way of finding dealers, I don't know because I have never clicked on it. All I care about is the calculator. 199.125.109.43 (talk) 22:51, 16 July 2009 (UTC)
 * Actually, what is unsuitable is your narrowly defined prohibition on any links that include any links to anything that you see as advertising. There is nothing wrong with any of the links. You will notice that no one can complain about the links - what you are complaining about is the links on those links, which of course we have no control over. But if you can find better ones, please use them. The point is that you can not eliminate useful information because you don't like the fact that it includes a link to an advertisement - you have to judge the link by the information it provides, not by any additional links it may have. Those can be ignored. If everyone followed your narrow definition of EL, there would be no ISBN numbers, for example, because you can get to Amazon through them, or company websites, for that matter, even if the article is about the company. 199.125.109.43 (talk) 21:39, 16 July 2009 (UTC)
 * Straw man. - MrOllie (talk) 22:04, 16 July 2009 (UTC)
 * Please confine your remarks to the content. 199.125.109.43 (talk) 22:08, 16 July 2009 (UTC)
 * Use NREL's solar calculator. Mrshaba (talk) 23:37, 27 July 2009 (UTC)

In response to the request for a third opinion: Links to solar power calculator sites (for home installations) are not directly relevant to the topic of Photovoltaics, as the page is not about home installation of solar panels, and so fail WP:ELNO #13, should these sites also promote a particular product for sale, they would fail WP:ELNO #5. This particular article fails WP:DIRECTORY and would benefit from a general link to in order to replace a significant number of unnecessary links.—Teahot (talk) 15:01, 17 July 2009 (UTC)


 * While IP199's desire to use them is understandable, I concur with both MrOllie and Teahot, the link(s) are a fairly blatant violation of WP:EL and are not appropriate for inclusion in this article. Doc  Tropics  15:35, 17 July 2009 (UTC)
 * While it is true that the article is more than dominated by the most interesting of applications - large photovoltaic power stations, it is totally false to state that "the page is not about home installation of solar panels", as the page covers all applications of photovoltaics, from wrist watches to the International Space Station, and everything in between. So I would like to see a specific reason for not including links to the calculators. You will note that language like "the link(s)" and "fairly blatant violation", though horribly wishy-washy in itself (is it fairly or is it blatant?), are not useful to the discussion without specifying specifically which links and what reason makes it a violation. As I see it there is clearly nothing wrong with the links, nor the map. As I see it, user MrOllie is not concerned with the content of any of those three pages (he talks about lists of installers, yet there are no lists of installers on any of those three pages), but what links are on those pages, and where you can get to from those links. That we have no control over. If the Herald Tribune runs a story about something and we link to it, who knows or cares what adverts are on that page, and where you can get to if you click on them? Please be specific about what links you are talking about, and what your concern with them is, if any. The section below is another matter, and not what this section is addressing. But why anyone would want to link to a linkfest but not linkfest here is beyond me. 199.125.109.81 (talk) 14:44, 19 July 2009 (UTC)
 * Having reviewed my opinion, I cannot consider your criticism that it is "totally false" as reasonable. Should you wish to check the OED, you will find that photovoltaic is defined as "relating to the production of electric current at the junction of two substances exposed to light", while the current lead of the article defines it more widely as "the field of technology and research related to the application of solar cells for energy by converting solar energy". Neither of these definitions of "Photovoltaics" mention any financial aspect of installation of solar panels or any other photovoltaic product for that matter (noting that application is not the same thing as installation). The guidance of ELNO states the link should be directly related to the subject of the article. Consequently I will not be revising my opinion. Thank you for your feedback.—Teahot (talk) 15:48, 19 July 2009 (UTC)
 * I have long ago stopped trying to change anyone's opinion, electing instead to simply point out whether it was correct or not. Did you think that solar powered wrist watches, and homes with photovoltaics had the solar cells not there for the energy they needed? And how on earth does one apply something without installing it? Your logic is flawed, to say the least. The link is directly related to the subject matter, because it illustrates how much solar power can be obtained at any given location using photovoltaics. And thank you, as well. 199.125.109.81 (talk) 12:54, 20 July 2009 (UTC)