Talk:Photovoltaics/Archive 3

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Archive 1

Archive 2

Archive 3

External Links

I hadn't previously noticed, but Teahot makes a very good point in the section above: this article does not currently comply with WP:DIRECTORY; it contains a total of 56 external links. Since I'm not a regular contributor on this page I don't want to just jump in and start deleting things, but something should probably be done to trim the EL section. Doc Tropics 15:46, 17 July 2009 (UTC)

Advantages

The quoted figure of 15 TW does not correlate with the wiki page List of countries by electricity consumption. I fear the author of 15 TW includes all energy usage, not simply electricity and further to that discounts for conversion efficiencies. In short, I think it is wrong by an order of magnitude and should read 1.9 TW and hence 47, 000 times. —Preceding unsigned comment added by 65.120.117.2 (talk) 20:39, 19 August 2009 (UTC)

Interesting. Our article World energy resources and consumption claims 16 TW in its intro, but that figure is sourced to a US DoE document which actually quote a different figure, but gives the unit of measure as quadrillions of BTUs with no mention of Terrawatts, so someone apparently performed a bit of OR there. Furthermore, when I checked the source that was include in this article, the figure given there was actually 12 TW; however, it turns out that the source is actually a set of background notes for a speech given by a Canadian professor and largely focused on social issues. The professor is legit, and apparently an authority in his field, but this doesn't really seem to pass muster as a reliable source; surely there is some better way to directly establish this info? If not I think we need to mention the different figures and try to explain why they are different, how they were arrived at, or at least who came up with them. Doc Tropics 21:09, 19 August 2009 (UTC)

Since photovoltaics (along with wind) will soon replace fossil fuels, it is more practical to make the comparison between total energy and photovoltaics, not total electricity. The conversion between Btu/yr and TW is trivial. 199.125.109.37 (talk) 02:25, 25 September 2009 (UTC)

94% increase source

In the article there is this line: "making it the world’s fastest-growing energy technology, and then increased by 94% in 2008" with this source: [1]. However, at that source I cannot seem to find the quoted value. Am I missing something?

When searching for such values, I came across this page: [2], which has some good data in excel tables linked from it. That data confirms the previously mentioned doubling every two years and 48% growth. But I am still interested in the 94%. --85.183.19.48 (talk) 10:37, 23 September 2009 (UTC)

94% was based on preliminary data, I believe, but later on the article has a source for 110%, so the lead was corrected to match that. The main point though, is that at 48% growth it was the world's fastest growing energy technology. Whether that increase continues, or accelerates even farther remains to be seen. The page you quoted from Earth Policy was published in December of 2007, so likely does not include data from 2008. 199.125.109.37 (talk) 02:18, 25 September 2009 (UTC)

Merge with Photovoltaic module

This article ought to be merged with the Photovoltaic module article as they both essentially talk about the same thing. Ufim (talk) 05:54, 16 December 2009 (UTC)

Merge with solar cell

This article ought to be merged with the solar cell article as they both essentially talk about the same thing. —Preceding unsigned comment added by Happytohelp21 (talk • contribs) 09:13, 11 December 2009 (UTC) solar

Materials used in PVs

It seems that the first reference link is a dead link, this should get fixed. 150.250.213.174 (talk) 13:04, 24 November 2009 (UTC)

Cost calculation

Hi. I'm struggling to replicate the cost calculation. Here's a google spreadsheet in which I've done the calculation for a single example. The calculation is pretty simple. Unless someone can point out a mistake in mine, or justify a different method I think the numbers in the table should be updated? Grj23 (talk) 08:40, 23 February 2010 (UTC)

In my opinion the table is original research and ought to be deleted unless a reference for it can be provided. Besides, based on the small amount of information provided about it, it is difficult to understand exactly how the calculations were performed, which would explain why you're having trouble reproducing it. Furthermore, I'm rather certain they neglect mortgage tax credits (for residential systems), investment tax credits (for commercial systems), inflation, discounting of cash flows, and degradation of panels over time, among other things. Yes, all of those things make the analysis rather complicated, but when you're talking about a system paid for over 20-30 years these all have a significant impact on the final calculation and neglecting them necessarily leads to distorted conclusions.--Squirmymcphee (talk) 15:18, 28 February 2010 (UTC)

Caltech does not claim 85% efficiency!

I just reversed an edit indicating that Caltech researchers are claiming 85%-efficient solar cells in the lab. 85% is about the theoretical thermodynamic limit on the conversion of solar energy to electricity, but achieving it requires a perfectly lossless solar cell with an infinite number of bandgaps (i.e., made of an infinite number of materials). Caltech is not claiming to have achieved this, rather they have simply issued a poorly worded press release about an innovative single-junction silicon solar cell (which, therefore, has a theoretical maximum efficiency of about 32%).

In greater detail, they claim only that their cell "absorbs 85 percent of total collectible sunlight," which is much different from claiming 85% efficiency. First of all, only about 65% of the photons in the solar spectrum are collectible by single-junction silicon solar cells, so only about 56% of the total solar spectrum can be collected by these cells. The high quantum efficiency of these cells means that nearly every photon collected will be converted to an electron-hole pair, but nearly every photon collected will also carry an amount of energy higher than the bandgap energy of silicon -- and anything in excess of that will be converted to heat, not electricity.

I believe I read someplace that the actual efficiency of their device is expected to be in the 12-15% range (but don't hold me to that). Considering how little silicon they used, that is a much bigger achievement than it might sound, particularly if they can do it cheaply.--Squirmymcphee (talk) 15:31, 7 March 2010 (UTC)

Intro is gushy, not neutral POV.

The introduction is overly gushy about how good it is and how fast it's growing. Gag me! It sounds like what they said about soccer in the 1970's. "Fastest growing sport!" Yada Yada Yada. Is the rest of the article the same drivel? ...... I will see. But please, neutralize the intro. Make if dry and straightforward, not promotional. Gah!

108.7.12.26 (talk) 03:50, 27 June 2010 (UTC)

So, is there a neutral way that states the same facts that would meet with your approval? How would you relate the statistics? *Sombody* is dead keen on solar PV and that's making the growth notable; even cloudy places like Ontario and Germany are building solar PV capacity, independent of what the Wikipedia is saying. --Wtshymanski (talk) 18:55, 27 June 2010 (UTC)

Disadvantages

Although the fuel to make electricity from solar (the sun's rays) may be free and pollution free, the process of manufacture of the panels and installation is not free or pollution free. Also there may be a disposal fee when the panels expire. There is also a maintenance consideration, the panels are probably not maintenance free (they are subject to hail damage and may need to be cleaned and the inverter and metering equipment needs to be maintained). The sun only shines for 1/3 of the day, the capital costs are incurred 24 hours a day. At least 1/2 the cost of electricty is capital costs as opposed to fuel costs. It is a subsidy in itself to require the power company to purchase the kwh at the retail cost. A more market fair purchase price would be the wholesale cost of electricty which is more like $.06 per kwh as opposed to the $0.12 typical wholesale cost (although California has higher PEAK rates, not all localities charge PEAK rates, especially for homeowners.

Electricity from solar panels will be most successful in areas with high electricity rates. Right now the island of Lanai in Hawaii has the highest cost per kwh (somewhere around $.50 per kwh). If the panels start making economic sense it will be in locations such as these first. —Preceding unsigned comment added by Aviatorpilotman (talk • contribs) 15:44, 4 July 2010 (UTC)

Fascinating. Do you have a reference for all that, if so it should be in the article, if not, this is not the place to speculate. --Wtshymanski (talk) 19:51, 4 July 2010 (UTC)

Well it WAS up as high as .50 per kwh, but it appears to have fallen to about .37 according to this website: http://puc.hawaii.gov/industries/Energy/effective-rate-summary/20100601%20Electricity%20Rates%20and%20Oil%20Prices.pdf —Preceding unsigned comment added by Aviatorpilotman (talk • contribs) 05:42, 5 July 2010 (UTC)

Also, here is a table of electricity rates in the US, state by state: http://www.eia.doe.gov/electricity/epm/table5_6_b.html —Preceding unsigned comment added by Aviatorpilotman (talk • contribs) 05:57, 5 July 2010 (UTC)

This is an interesting topic but Wikipedia is not a place for editors to propose their own theories however much evidence they can collect (see WP:OR). Rather than building our own case from scratch, we need some solid references such as notable persons' peer-reviewed papers or interviews with notable alternative energy theorists on this topic. Joja lozzo 12:16, 5 July 2010 (UTC)

What is this article supposed to be about?

We have Solar power, Solar energy, Solar cell, Solar panel, Solar array,Photovoltaic cell, Photovoltaic effect, Photovoltaic array, Concentrating solar power, and probably others I haven't found yet. Much of the same material is repeated in each of these - we read about the wonders of solar power under Photovoltaic cell, for instance, and this article gets deep into the intermittency and financing. It's also amusing that Photovoltaic cell has a hatnote redirecting to solar cell, but says that it's a type of photoelectric cell which is a redirect for solar cell!

I suggest we reorganize this along the lines of wind power and related articles. Keep solar energy as it is, solar power will talk about PV and steam power plants, solar cell would absorb all of photovoltaic cell and photoelecric cell and just talk about the device materials and physics, photovoltaic array will talk about pointing cells and the sun, etc. but not get into financials and envirionmental impact, etc. We may find that photovoltaics disappears completely if none of its content is not contained in other articles. --Wtshymanski (talk) 16:56, 14 July 2010 (UTC)

I agree, but maybe photovoltaics can stay as an index to the whole matter: e.g. "PV is the science and thechnology of converting...; if you are interested in working principles look at solar cells, for economics look at ..."; i.e. not much more than you have told just here.--GianniG46 (talk) 17:46, 14 July 2010 (UTC)

Here are some of the chapter titles out of S. R. Whenham et al., "Applied photovoltaics (2nd ed)" ISBN 1-84407-401-3, which might suggest topics suitable for inclusion in this article:

The Characteristics of Sunlight (particle-wave, blackbody, insolation)
Semiconductors and P-N Junctions (band model, doping, types, absorption, recombination)
The Behaviour of Solar Cells (effect of light, spectral response, temperature, parasitic resistance)
Cell Properties and Design (Efficiencies, optical losses, recombination losses, grid spacing, other losses)
PV Cell Interconnection and Module Fabrication (design, heating, structures, insulation, protection, degradation and failure)
Stand-alone PV system components (solar modules, batteries, inverters, balance of components)
Desinging stand-alone PV systems
Specific purpose PV applications
Remote area power systems
Grid connected systems
Water pumping system components and design

and several appendices of data. We'd list the major points here, and put the details in the relevant cell/module/array articles as they are developed. --Wtshymanski (talk) 15:12, 15 July 2010 (UTC)

Use summary style

I honestly don't think we need to bring in a whole lot of new material and reinvent the wheel. This should be the main article for many of the shorter articles relating to photovoltaics, and most of the content should come from the shorter articles, via WP:summary style. This is where the main article includes summaries of the shorter articles and has a link to them. So there will be some overlapping content but there is no problem with this, as it is the way we usually do things on WP. Johnfos (talk) 22:02, 15 July 2010 (UTC)

Rereading, I phrased it badly. Yes, this can be the overview, and the details pushed down into the detail articles (which aren't necessarily shorter!). The topics above naturally lend themselves to distribution over existing articles. But we don't need to give all the same details in all the articles. --Wtshymanski (talk) 03:24, 16 July 2010 (UTC)

Lead section

I think the old lead was better than the current one, which seems rather vague and confused, and seems to focus on the small-scale novelty value of PV.

This sort of material needs to be in the lead:

As of 2010, solar photovoltaics generates electricity in more than 100 countries and is the fastest growing power-generation technology in the world. Between 2004 and 2009, grid-connected PV capacity increased at an annual average rate of 60 percent, to some 21 GW. Off-grid PV accounts for an additional 3–4 GW. Renewables 2010 Global Status Report p. 19

-- Johnfos (talk) 03:51, 19 July 2010 (UTC)

I've updated the lead to incorporate this new material. Johnfos (talk) 00:26, 21 July 2010 (UTC)

Assessment

This article is rated as a 'B'-class article. It does not fulfill 'B' criteria and therefore I will downgrade it to 'C'. The main issue related to references. Although the article has a number of references, it still has a 'citation needed' tag for almost a year. Several paragraphs and even subsections (e.g. 'Optimum Orientation of Solar Panels', 'Solar Power satellites') are totally without references. The style of references is unclear and references should be formatted according to applied style. A number of references are actually dead links. Beagel (talk) 07:46, 24 July 2010 (UTC)

many references no longer reachable, e.g. ^ Strickland, Tonya (2008-04-24). "$1 billion-plus Carrisa Plains solar farm could power 190,000 firms". The San Luis Obispo Tribune. Retrieved 2008-08-19. --LowEarthOrbit (talk) 14:42, 14 August 2010 (UTC)

Merge from

Photovoltaic effect is three paragraphs, much of the first of which is devoted to explaining our confusion, and the third is a one-line "discovered by" paragraph. I suggest we merge it here until some physicist with time on his hands has a chance to write a proper photovoltaic effect article. --Wtshymanski (talk) 13:42, 22 September 2010 (UTC)

Current developments

"A March 2010 experimental demonstration of a design by a Caltech group which has an absorption efficiency of 85% in sunlight and 95% at certain wavelengths (it is claimed to have near perfect quantum efficiency).[41] However, absorption efficiency should not be confused with the sunlight-to-electricity conversion efficiency."

Quantum efficiency is the photon-to-electron conversion ratio. If the quantum efficiency is claimed to be near-perfect, is not the second sentence a bit strange? —Preceding unsigned comment added by 194.109.22.149 (talk) 15:39, 8 January 2011 (UTC)

photos

should we not change the photos that are in the text? If you're talking about photovoltaics, I would put in a detailed picture of a single cell, instead of a somewhat arty photo of an installation in Austria. If we put in a picture of a complete installation, then it should be a larger scale one. 194.53.253.51 (talk) 14:17, 25 May 2011 (UTC)

I honestly don't see a major issue here, but have added an image of Lieberose Photovoltaic Park, which is a larger scale installation. Johnfos (talk) 01:13, 27 May 2011 (UTC)

Insolation sources

I moved the following discussion here from the main page Disadvantages section:

Insolation figures of 3–7 kilowatt·h/m² for the contiguous US are from the map colors which slightly contradict the table above which claims 900 to 2100 yearly insolation, that makes 2.46 to 5.7 daily. Also, second cite does not claim 3 or 7, third cite also makes no mention. There is also a need to clarify what kind of insolation is meant, presumably vertical.

Joja lozzo 20:00, 3 September 2011 (UTC)

photovoltaic effect and the photoelectric effect

I intend to clean up the prose and claims surrounding the photovoltaic/photoelectric discussion. The photovoltaic effect discussed here (there is more than one PV effect) is the same phenomena as the photoelectric effect, except that the interface for the freed electron is a conducting electrode (anode or cathode) instead of the vacuum.

It has been a few years so things may have changed since Jacques Pankove wrote "Optical Processes in Semiconductors," so let me know if anyone feels strongly one way or the other, hopefully with a trail to some evidence. =) Cheers, J.H. Gorse (talk) 02:58, 15 September 2011 (UTC)

Disadvantages need update

Please explain what needs updating in the disadvantages section. I think the issues discussed there are all still a concern. What is it hat's changed recently? Joja lozzo 19:52, 3 September 2011 (UTC)

See analysis of the POV section below......

Avram Primack (talk) 20:40, 8 November 2011 (UTC)

POV tag

There is some very one-sided discussion in the Disadvantages section...

The first paragraph basically says that solar electricity is not produced at night and requires alternate sources of power, such as diesel generators which consume costly fuel. Yet, there are applications for PVs where the power is simply taken when available, such as with water supply and desalination plants, and so in these cases no alternative energy source is needed. If an alternative energy source is used it may be wind power which is usually stronger at night and so dovetails well with PV. No costly fuel is involved.

The fourth paragraph on RoHS is really quite a rant. The issue is CdTe cells, as the source says, but no mention of CdTe is made in the WP text. There is also no mention of manufacturers including First Solar which have implemented module recycling programs. Very one-sided discussion. The issue is already better covered in many CdTe-related articles.

Reference is also made to the poor economics of PV, but this info is outdated. As of 2011, the price of PV modules per MW has fallen by 60 percent since the summer of 2008, according to Bloomberg New Energy Finance estimates, putting solar power for the first time on a competitive footing with the retail price of electricity in a number of sunny countries. There has been fierce competition in the supply chain, and further improvements in the levelised cost of energy for solar lie ahead, posing a growing threat to the dominance of fossil fuel generation sources in the next few years.^[1] As time progresses, renewable energy technologies generally get cheaper,^[2]^[3] while fossil fuels generally get more expensive:

The less solar power costs, the more favorably it compares to conventional power, and the more attractive it becomes to utilities and energy users around the globe. Utility-scale solar power can now be delivered in California at prices well below $100/MWh ($0.10/kWh) less than most other peak generators, even those running on low-cost natural gas. Lower solar module costs also stimulate demand from consumer markets where the cost of solar compares very favorably to retail electric rates.^[4]

This article needs more work to integrate different points of view, and to move away from a simplistic advantages/disadvantages discussion. Johnfos (talk) 23:37, 3 September 2011 (UTC)

It is about disadvantages so we expect negative criticism. I agree that we need to keep it updated but I think the POV tag is inappropriate. If the facts have changed then we should edit it to take that into account but I think calling once-accurate statements POV is unnecessary. I assume you are a propoent of the technology (as am I) but I urge you to be even handed in pointing out its drawbacks. Joja lozzo 23:55, 3 September 2011 (UTC)

In terms of the bigger picture, what I am saying is that an advantages/disadvantages discussion is inherently not neutral and that we need to better integrate different points of view, through some restructuring of the article. A section full of negative criticism, much of it not well-founded, is inherently POV. Hence the POV tag. Johnfos (talk) 00:15, 4 September 2011 (UTC)

======================================================

Is this formulation more Neutral? Every generation system has advantages and disadvantages. Fuel is Carbon footprint and limited resources, wind is noise, nuclear is risk, hydropower is land grab, etc. Solar as well, is not the energy perfect mantra. It bears some constraints or drawbacks which must be taken into account at the system design stage.

1) Solar energy is by definition available only during day time. It is also impacted by the sky condition (clouds, pollution). Therefore, like for any other non fossil energy, storage is necessary in order to maximize the usage of the installation and this transformation has a cost. The storage will be done by conventional and well known permanent systems either at the plant level (ex: charging batteries) , or at the network level (ex: pumping up water into a dam).

2) Solar technology is still a young industry and the prices of the solar cells are far from their asymptotic value provided by a mass production. Without any driven advantage, it would take ages to take off. The "youth" overcost is compensated since the years 2000 locally by government subsidies in most countries (ex: California, France, China, Germany) - examples to be cited- by means of tax exemption on new installation, and high feed-in tariffs. These subsidies are linked to an environmental policy or bound by economical constraints and may vary from time to time, or vanish. This will certainly happen one day.

3) For the same reason than above the Return on Investment of a solar installation will depend on the subsidies.

4) there is still a debate on the inclusion of the solar cells in the WEE and ROHS European directives (a). Present technology includes Cadmium Telluride (CdTe). Everybody agrees on the high level of risk, including the manufacturers. Some argue that the industry itself will take care of these risks, some argue that not everything can be controlled and a control at the origin is the best proof. Obviously, the European policy today favors the solar cell activity by minimizing the constraints (exclusion of PV cells from ROHS dierective (b); nevertheless after the take off period, it is most probable that this industry will have as well to comply with these directive, like any other device industrially used on a large scale(switchgears, electronics, etc). The technology of the cells is also evolving towards less polluting technologies.

Note (a): http://ntsa.eu/index.html

Note (b): https://www.eupvsec-proceedings.com/proceedings?char=R&paper=7468' — Preceding unsigned comment added by Roland flageollet (talk • contribs) 09:03, 29 November 2011 (UTC)

Solar Power not being available during the day is certainly a disadvantage. Of course there are some applications which only require power during the day, but the mere existence of these applications doesn't merit taking it out of the disadvantages section. Furthermore wind power can be just as expensive as other sources of energy so using this as a nighttime energy source is no guarantee of low cost power generation. I've also never heard of wind "usually" being stronger during the night, and if those were the only two power sources used without a fairly large energy storage medium I could see blackouts becoming a large problem. — Preceding unsigned comment added by 131.151.147.100 (talk) 05:45, 6 December 2011 (UTC)

Where to place schematics?

I've made a schematic diagram of residential systems, but have no idea where to put this in. Is there a separate article that writes about the system, or is this article simply lacking such descriptions? Thanks, --S-kei (talk) 18:36, 30 October 2011 (UTC)

Nicely done. It might go well somewhere in Solar power. That way we can have one article to talk about the power generation application, and leave the "photovoltaics" article to talk about fundamental physics. --Wtshymanski (talk) 19:11, 30 October 2011 (UTC)

Thanks! I added it there. --S-kei (talk) 22:04, 30 October 2011 (UTC)

Analysis of the POV disadvantages section

I read the section and the critique is here below. I dont see what the point of view tag is there for. A better tag would be a trivial information tag, but I don't think we have that yet. Most of the statements are too picky to give much credence too, and many of the disadvantages are not couched in comparison to anything else that allows their evaluation. Here are my line by line comments....

"Solar electricity is not produced at night and is greatly reduced in cloudy conditions requiring alternate sources of power. " ...............so what? This means that there has to be an energy storage system (pumped storage of water) or it is only technology usable in daytime. This is obvious...is it important enough to make a disadvantage....nuclear power plants and coal plants shut down for extended periods of time too....Solar provides power during peak periods. This reduces the need for more large power plants that sit idle at night during off peak hours...not a disadvantage.

" such systems use a grid tie inverter to convert direct current (DC) alternating current (AC) incurring an energy loss of 4–12% " My understanding is that by the time electrical power gets from a conventional power plant to a user around 90 percent of potential energy has been lost as heat... this is a technical issue that is not on the level of other power sources... is it worth mentioning? Seems to be an advantage compared to conventional electric generation.

"Solar electricity production depends on the limited power density of the location's insolation." True if you are using a point as your reference, not a two dimensional surface...the question is not whether you could produce enough energy to make a bomb, just enough to be economically viable....The real comparison is the footprint on the ground per watt generated. For this solar wins over coal and nuclear. Only a problem when I want a kajillion watts in one place and dont have a place to put the panels...but if I want a kajillion watts in one place I am probably connected to the grid anyway. Not a disadvantage.

"Solar electricity is more expensive than most other forms of small-scale alternative energy production." Not for isolated villages in Africa, or cellular telephone relay stations where there is no piped in power. Is this not a trivial objection that says that power costs vary with power source without regard to what the user might want? In some places it is better to have a source with no moving parts so it dosent have to be started, serviced, fueled, etc etc.... The market sorts out this kind of difference. Not a disadvantage, or if it is then we should dump all the nuclear power plants now, since they cost more than almost any other electric source.

"Without governments mandating "feed-in tariffs"[notes 1] for green solar energy, solar PV is less affordable to homeowners than solar hot water or solar space heating.[notes 2]" This is a comparison of solar energy technologies, and irrelevant to a homeowner who wants electricity. The question of feed in tariffs might be reasonable if the article explains that this means that surplus power is supplied to the power company free of charge....Also, almost every power source is operating in a subsidy environment that distorts its price...Not a disadvantage, or we should scrap the national highway system in the US because it wouldn't exist without subsidies...

"Photovoltaic panels are specifically excluded in Europe from RoHS (Restriction on Hazardous Substances) since 2003 and were again excluded in 2011. " Are the substances in question really toxic? If so explain that here. The objection hangs without any justification. Just remember that there are objections to other power sources too. Coal is the main source of thorium (a dangerous radioactive element, http://www.ornl.gov/info/ornlreview/rev26-34/text/colmain.html ), and nuclear wastes need to be sequestered for millenia before they are safe to release in the environment. You might try asking residents that live next to coal plants or a citizen of Japan. What are the health risks?What are the comparative health risks? Examples not assertions hold more sway. Or, we should shut down all coal power plants because they cause thousands of deaths from respiratory illness brought about by coal smoke....

What is missing from the section is an analysis of energy return on investment (I am not qualified to make this) or a discussion of panel life and disposal. These are real disadvantages if the Energy return is as low as shown on http://en.wikipedia.org/wiki/File:EROI_-_Ratio_of_Energy_Returned_on_Energy_Invested_-_USA.svg . Where and how are panels disposed of? Do they cause any health effects? Are these significant relative to the disposal of coal ash (toxic) and nuclear waste (mutagenic)?

"Much of the investment in a home-mounted system may be lost if the home-owner moves and the buyer puts less value on the system than the seller.[notes 3]" Huh??? The home value comes from the market, not the homeowner. New homeowners may put less personal value on having a system, but the market will evaluate it the same way it does a new patio.

I could make the same analysis of the advantages section, so don't be fooled by my tone and approach. My analysis suggests that the section contains semantic disadvantages, some trivial scientific limitations, but no significant disadvantages. There is no obvious point of view bias, but no significant information. Fix it by making the disadvantages significant, or delete it please. In current form it is at best misleading to the uninformed public.

Avram Primack (talk) 20:01, 8 November 2011 (UTC)

I've removed "Solar electricity is not produced at night and is greatly reduced in cloudy conditions requiring alternate sources of power. " alternate sources are required by any power source, it's not specific to solar power, it's a disadvantage of any power source, when there is no wind, there is no wind power when there are no waves, when you run out of coal, gas, have a ban on uranium imports, and so on. Yes, when there is no sun there is no solar power, it's not notable. It's not a disadvantage.

rm'd "grid tie inverter" sentence, it's in the wrong section. It's not a disadvantage, it's just a storage method.

"Off-grid systems use either storage batteries which also incur significant energy losses and require regular maintenance[citation needed] or engine-generators which consume costly fuel."

these are just two of the storage systems, being presented as the only two possible. There are others. Further storage is not required in many applications, agreeing with the cn editor, and rm'd.

"Solar electricity production depends on the limited power density of the location's isolation. Average daily output of a flat plate collector at latitude tilt in the contiguous US is 3–7 kilowatt·h/m²/day[79][80][81] and on average lower in Europe."

Not a disadvantage of photovoltaics generally, to do with economics of remote area power systems. It could be moved to the other section of the article no problem though, but isn't an example of a disadvantage of photovoltaics. example, there are plenty of power sources on the desk in front of you, but that has no effect on photovoltaics in a calculator or clock. Photovoltaics aren't dependent on power density of the location's isolation. that belongs in an article about remote area power supplies, possibly, but it'd still fail there as it's still not dependent as some people choose PV for reasons other than economic ones.

"Solar electricity is more expensive than most other forms of small-scale alternative energy production."

this is so cn, as the cites are specific to limited apps, not general. better integrating it into a particular section, maybe.

"Solar electricity is more expensive than most other forms of small-scale alternative energy production." "Without governments mandating "feed-in tariffs"[notes 1] for green solar energy, solar PV is less affordable to homeowners than solar hot water or solar space heating."

The article covers use on satellites too. wrong section,. integration is better.

Photovoltaic panels are specifically excluded in Europe from RoHS (Restriction on Hazardous Substances) since 2003 and were again excluded in 2011. California has largely adopted the RoHS standard through EWRA. Therefore, PV panels may legally in Europe and California contain lead, mercury and cadmium which are forbidden or restricted in all other electronics.

Is significant and well qualified.

Added "In some states of the United States of America," to "Much of the investment in a home-mounted system may be lost if the home-owner moves and the buyer puts less value on the system than the seller" but would support it's deletion as it is in the wrong section / article / not significant. Penyulap_talk 06:53, 3 December 2011 (UTC)

Avram Primack, the section "Photovoltaic panels are specifically excluded in Europe from RoHS (Restriction on Hazardous Substances) since 2003 and were again excluded in 2011. California has largely adopted the RoHS standard through EWRA. Therefore, PV panels may legally in Europe and California contain lead, mercury and cadmium which are forbidden or restricted in all other electronics." looks all ok, "Are the substances in question really toxic?" is not a question for wikipedia, which is just an encyclopedia, it's like, did they pass some legislation or make some statement to the media, and then is it relevant and significant to the topic. If it's actually wrong, you'd find other sources saying that the use of those substances IN PHOTOVOLTAICS (very important that part) is ok. has to be about photovoltaics, or it has to be a comment on that legislation or statement. Penyulap_talk 13:14, 3 December 2011 (UTC)

I agree with these edits but not for any of the reasons given. Both this analysis of the section and the removed discussion of disadvantages appears to be OR. Most of the section lacked citations and those that were provided were primary sources or unreliable commercial web pages. Even what is left appears to be unsupported. We need good secondary reviews of the topic for this section. Joja lozzo 15:13, 3 December 2011 (UTC)

The map of solar energy generation centers is clean and simple. Unfortunately that is includes clean of limitations of current reality. Too much rainbows and ponies thinking.

No one has given the same environmental impact considerations that would be asked if it was a coal plant or even a parking lot that large. No "where does the water go if it ever rains?" (Hundred meter deep flash floods would happen for areas this large.)

1 Power transmissions without superconductors decay with distance from the power generation. You can lose 50% energy in transmission lines over distances as short as a few hundred kilometers.

2 the locations proposed are the optimal areas for current weather such that distributed solar generation near users instead would take considerably larger area

3 Stealing 8% of solar warmth over areas as large as proposed...will create permanent intense weather systems. Well permanent until the resulting weather destroys the solar energy plants or clouds it over and a cycle of ever expanding and less efficient generation begins. Keep in mind that hurricanes represent the result of just 1-2% differences in energy distribution in the atmosphere over less than a hundred kilometers area at its core and much smaller differences in outer regions.

4 Do you have any idea of the ecosystem under an area of permanent covered dark that large? Bat crap on solar cells might be the least of issues.

Let us see these solar ideas drawn out with full environmental impact considerations before we start bouncing around clapping our hands in delight. Not that solar is not viable...but it isn't going to be as simple or even as clean as the Church of Solar Energy preaches.

72.182.15.249 (talk) 23:02, 6 December 2011 (UTC)

While much of the article is clearly written from a pro-solar POV, I think a certain degree of that is expected and accepted; however, once we get to the "Disadvantages", the statement re: lead usage is blatant editorializing.

To begin, it's not a statement that has anything to do with "Photovoltaics." If this were an article about toxic by-products of energy production, public policy or governmental attitudes toward energy production (renewable or otherwise), or usage of heavy metals in general or specific, this may be a pertinent statement, thought may still be classified as opinion.

But primarily, the only way this information is presented as a "Disadvantage" isn't because lead or other toxic substances are used in the production of photovoltaics (which incidentally, if we're going to label a disadvantage, you may as well say it's bad because the systems use batteries then start on a general attack on power storage); the disadvantage is that Europe and California have created an exemption to the prohibited materials list for usage in photovoltaics. Perhaps it seems a subtle difference. but in actuality it's the difference between saying "fossil fuel combustion often produces undesirable by-products beyond CO2 and Water," and "one disadvantage to fossil fuel combustion is that Germany and Detroit create favorable legal conditions for automobile production." See what I mean? The article attacks government policy without establishing to what degree lead and/or other toxic metals are necessary for production, why any/all lead usage is bad (even under regulated conditions), or even why Europe or California's exclusion or inclusion on a prohibited materials list is so important or meaningful vs. what other governments do or don't include or exclude it or have prohibited materials lists, etc., etc...

I'm quite far from an expert or even an educated novice in areas of science or technology; however, when encountering such a fault in logic at the end of a piece I was enjoying and taking as objective forces me to question the reliability of the article overall. Honestly, since so many others have mentioned it, I'm curious why it hasn't been removed altogether, which I recommend. --76.89.150.16 (talk) 20:31, 9 April 2012 (UTC)

I have removed the lead usage section as being off-topic and covered elsewhere. Johnfos (talk) 23:46, 9 April 2012 (UTC)

at the end of the 'Solar cells' section citation link [31] is broken

Link broken for the following paragraph:

"The EPIA/Greenpeace Advanced Scenario shows that by the year 2030, PV systems could be generating approximately 1.8 TW of electricity around the world. This means that, assuming a serious commitment is made to energy efficiency, enough solar power would be produced globally in twenty-five years’ time to satisfy the electricity needs of almost 14% of the world’s population.[31]"

As well as this, if the actual citation should be to "http://www.greenpeace.org/international/en/press/releases/greenpeace-report-proves-solar/" , then it is actually Solar thermal power, not photovoltaic systems, which is expected to provide the energy in question. — Preceding unsigned comment added by 129.31.89.144 (talk) 22:13, 7 December 2011 (UTC)

Solar Cells section

The solar cells section is not at all a specific section title and it has a lot of statistics about different countries that is irrelevant. I think all this data should be removed from the article as actual statistics on deployment of solar cells isn't what photovoltaics is about.

Shouldn't the page just explain what photovoltaics are? — Preceding unsigned comment added by Oliholmes (talk • contribs) 23:36, 9 December 2011 (UTC)

Which household where?

From the article: "Solar photovoltaics is growing rapidly, albeit from a small base, to a total global capacity of 69 GW at the end of 2011. The total power output of the world’s PV capacity run over a calendar year is equal to some 80 billion kWh of electricity. This is sufficient to cover the annual power supply needs of over 20 million households in the world." We need sources for the 69 GW figure and for the 80 billion kWh figure. Also we could express the figure in GWhs. What households are we talking about - American huge houses or homes in India? What is the annual energy consumption of the "household" and what is the source for this figure? Otherwise this is just a bullshit calculation using just some figures. --91.157.12.62 (talk) 15:46, 27 September 2012 (UTC)

Only sunlight?

Please clarify the first paragraph of this article if greater specificity is desired. PV devices are also used in indoor applications, (i.e. calculators) and in sensing devices. The term "solar radiation" thus excludes devices which are in fact photovoltaics.

See the first sentence. Those other uses are covered in the article Solar cell. Apteva (talk) 03:46, 6 April 2013 (UTC)

Units of Measurement

According to http://en.wikipedia.org/wiki/World_energy_consumption the 2008 figure for worldwide energy consumption was some 142,000 TWh this equates to 16.2 TWe this would assume nearly 90% sustained production efficiency(unlikely), a more realistic figure would be in the 50 - 60% region. US figures http://www.eia.gov/forecasts/ieo/ suggest a 2% rise per year which would place present energy demand at 156,000 TWh which at 60% sustainable production would require 23Twe production capacity. additionally 20% reserve is normally required to account for surge resulting in 27.7TWe. The centralised production suggested by the map shown in your article is very unlikely for many reasons including political, economic and technological reasons (transmission losses) and is therefore disingenuous at the least. To be more realistic using present technology, in order to supply the demands of the UK would require 50% of the total UK land mass to be covered by PV cells.

Regards

Phil Collins — Preceding unsigned comment added by 86.149.147.54 (talk) 12:19, 28 August 2013 (UTC)

"Solar voltaics are a renewable energy source" =

http://www.ctxwfs.org/Resources/Documents/Mineral_Resources_talk_version.pdf

Shouldn't the article mention that "renewables" aren't actually renewable and depend on extraction of raw materials that will eventually become infeasible to mine? Mustang19 (talk) 01:27, 29 August 2013 (UTC)

Accessibility, world view, and punctuation of abbreviation

I am not an expert in this field by any means, but I have edited the following section, as the meaning of the first sentence is difficult to comprehend, the overall fluency needed improvement, "pound" needed to be included to make the content universal, and the abbreviation "kg" needs a period/full-stop after it:

For both uses, the figure of merit of the solar panels is the power generated per kilogram (kg.) or pound, as an upper limit of the power the spacecraft has at its disposal per kg. spacecraft (including solar panels).^{[clarification needed]} To increase the power generated per kg., typical spacecraft solar panels use close-packed solar cell rectangles that cover nearly 100% of the sun-visible area of the solar panels, rather than the solar wafer circles, which, even though close-packed, cover about 90% of the sun-visible area of typical on earth-based solar panels. However, some spacecraft solar panels have solar cells that cover as little as 30% of the sun-visible area.^[5]

I am not precious about it, so if people agree that the edit is heavy-handed, I will revert it.--Soulparadox (talk) 17:04, 2 December 2013 (UTC)

A few thoughts from my perspective:

Don't think it was a heavy-handed edit. The statement was, and still is, extremely unclear.
I've made one small edit to the first part of that unclear sentence, that I think might be better. See what others think.
I'll try to get back here and improve the statement more generally, to get the entire statement clearer. But thought I'd let some time pass after my first edit since their had been some minor controversy between other editors.
I'm not an expert on WP:MOS stuff with respect to units. But generally, I would think that SI units do not require punctuation (full stop) after them to show it is an abbreviation. I did not check the MOS, it's just my observation from working with SI units frequently in spaceflight-related articles.

—Cheers. N2e (talk) 23:49, 2 December 2013 (UTC)

Claim "PV installations can operate for 100 years or even more"

In the source given for this statement (http://www.hienergypeople.com/advantages-and-disadvantages-of-solar-energy/) it is mentioned:

solar systems will generate energy for years. For 100 years or more actually and this has been experimentally proven

This is not the content of the given source, the paper referenced: https://web.archive.org/web/20110708094744/http://www.isaac.supsi.ch/isaac/pubblicazioni/Fotovoltaico/Conferences/Osaka%20(Japan)%20-%203rd%20WPVSEC%20-%20May%202003/s5o-c9-03%20analysis%20of%20weathered%20c-si%20pv%20modules.pdf

The degradation from 1983 to 2002 was measured:

- The initial light exposure of c-Si modules caused a mean power degradation of about -3%

- After one year of exposure, in absence of particular defects, all the modules became stable.

- Results from outdoor and indoor measurements indicate a power degradation, after 20 years, equal toabout -3%

Extrapolating this to 100 years is problematic because of observed particular defects and nonlinear degradation effects of the modules, for example:

- During last months, the tedlar backsheet detachment in some plant modules has been observed. This phenomena is rapidly increasing (0.8% of the plant in October 2002, 12.3% after 7 months). — Preceding unsigned comment added by Flo422 (talk • contribs) 13:21, 8 March 2014 (UTC)

Disadvantages?

The current disadvantages section just lists one disadvantage and quickly explains why it's potentially irrelevant. It is also a disadvantage compared to fossil fuels and not other clean energies. I am not an energy expert, and am in favor of photovoltaics, but surely we can list more disadvantages? For example:

Large land area for dedicated installations
Possibly higher maintenance cost and much greater hazards than concentrated solar power
No ability to work when there's no sunlight, compared to even concentrated solar power that can do some work (again, not an expert, but this is what I understood)

etc.

—Ynhockey ^(Talk) 09:57, 13 January 2014 (UTC)

Ah well, now, a year later, it has just gone altogether... I certainly agree that there is cause for at least some discussion of possible disadvantages. I would argue as a matter of fact that the tone of the article has a tendency to shine a very positive light (no pun intended) on photovoltaic technology in general (what did happen to the disadvantages section exactly?) I myself would like to see mentioned, at the very least the following points: -PV's inherently intermittent quality: currently, when there is a grid which provides power by use of PV plants, demand in electricity being inconsistent with sunlight, there is a need for other sources of power to use when sunlight is absent. -Production of PV technology is mainly done in countries that manufacture at the cheapest price, which means the ones with the lowest wages but also the ones using the cheapest energy source: China produces over 60% of PV (source : http://iet.jrc.ec.europa.eu/remea/sites/remea/files/pv_status_report_2013.pdf) and its energy is 78% coal fueled (source : http://www.iea.org/publications/freepublications/publication/kwes.pdf). -Similarly in all "high-tech" products, the compounds used to create PV cells are not "clean", nor energy neutral. The "Advantages" (!!) section states: "Production end-wastes and emissions are manageable using existing pollution controls.", but fails to elaborate on that particularly sensitive point. Transforming sand into crystalline silicium for instance requires energy of 11 kWh/kg (http://www.webcitation.org/6SfFES1Uq). Toxic or possibly toxic chemical compound, and compounds the extraction of which poses problems (geopolitical, environmental...) are used in almost all of the many different types of solar cells: Cadmium, lead, gallium arsenide, selenium, gallium, tellurium, ... (the list is long). -Doubts surrounding "life-expectancy" of PV cells (expanded on bellow) I'm sure, with some help from the community, we could build a worthwhile "controversy", or "Doubts" section out of that, don't you think, if not a "Disadvantages" one... Regards, Marcool04 (talk) 00:16, 14 January 2015 (UTC)

Blacklisted Links Found on Photovoltaics

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http://www.sgs.com/en/Energy/Energy-Sources/Solar/Services-in-the-Transportation-and-Installation-Phase/Final-Installation-Inspection.aspx
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