Talk:Solar cell

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Jan. 2005 – Jan. 2006

Simple explanation

Article says: "3. An array of solar panels converts solar energy into a usable amount of direct current electricity". It's explaining that a solar panel converts solar energy into electricity by saying that step 3 is converting solar energy into electricity! Someone with knowledge on this subject should write a more precise explanation. -- ironcito 16:23, 16 February 2006 (UTC)

Article removed from Wikipedia:Good articles

This article was formerly listed as a good article, but was removed from the listing because the intro is poor at the moment, with the first sentence 'A solar cell, or photovoltaic cell, is a not specifically a "p-n junction"' suffering from poor grammar, and also failing to start by defining what a solar cell is - much more important than what it is not! Worldtraveller 00:13, 12 March 2006 (UTC)

Good. This article is certainly not "good" as it is. It looks like it has been edited by half a dozen people, none of whom read anything written by the others. There are redundant sections that need to be merged and cleaned up. Ugh. I started to work on it, but it's too much for me to tackle right now. I did clean up a bad edit from ten days ago, though. Large chunks of source were deleted, including most of the see also and references, and the categories and interlanguage links. Apparently nobody is watching this page. Several people edited the page after the bad edit, without noticing the damage (like the fact that the page had no introduction.) --Srleffler 04:59, 21 April 2006 (UTC)

p-n junction contra-definition removed

I have removed the following comment from the introduction: "A solar cell, or photovoltaic cell, is a not specifically a "p-n junction". This is in fact a specific example of a photovoltaic device characteristic of the first generation of solar cells, including Si wafer devices."

I agree that the introduction should define a solar cell, and not provide excess information as to what it is not.

That being said, there is a strong preference in the solar cell wiki to use the description of a functional Si wafer photovoltaic device as the definition of a solar cell. A silicon-based photovoltaic cell is a special case of solar cell and does not provide the general case that defines the function of a solar cell. It is quite true that the great majority of commercial devices in large-scale production are made based on the science of a p-n junction in doped silicon, but there are many more types of solar cell devices that convert photons to electricity (based upon incident sunlight), yet cannot be defined using the function of a p-n junction and a resulting mesoscopic electric field in a space charge region.

If the information for a silicon solar cell device is highly valued, it would seem to deserve to be spun off to a separate wiki page. One could enter the topics such as the semiconductive properties of solid silicon,the electron configurations of atomic silicon, and the many internal varieties of silicon solar cells (e.g. single crystal, multicrystalline, Si thin film, etc.). Topics that are very relevant to current industrial production of silicon solar cells, but have little to do with a great number of emergent solar cells. In this way I believe the currently bloated and kludgey solar cell wiki could be cleaned and improved in scientific content such that solar cell represented the science of the device in the way that the fuel cell wiki page does. --Nanomech 12:06, 15 March 2006 (UTC)

"renewable" fact should be factored into price per delivered kWh

The article:

"Using the present (2005) commercially available solar cells and system technology leads to system efficiencies between 5 and 15%. Electricity generation costs range from around 50 eurocents/kWh (0.60 US$/kWh) (middle of Europe) down to around 25 eurocents/kWh (0.30 US$/kWh) in regions of high solar irradiation. Since, in grid-connected applications, this electricity is generally fed into the grid on the customer's side of the meter, it can be compared to prevailing retail electric pricing, which varies from between 0.04 and 0.50 US$/kWh worldwide."

So, what, do solar panels break over time? (They might need to be cleaned off or something, and I guess you can count this human labor - land cost for the cell sitting there is of course approximately zero).

If they don't have a very short life span, then the figure for cost per kilowatt-hour delivered has to say something like "over the first year". [Since as the soloar panel sits there (let's say it cleans itself off with some of the renewable energy) the produced number of kilowatt-hours goes to infinity (over a thousand years) while the price is something you just paid once.]

What is the lifespan of a solar panel? If it is not long-term, please update article to reflect this, otherwise please give greater emphasis to renewable aspect of this form of power generation.

Thank you.

81.182.77.88 12:52, 20 March 2006 (UTC)

The life span is usually 20 to 25 or more years depending on the type. The cost analyses usually already amortize the cost of manufacture over the expected lifetime of the solar array. Note that "over the first year" is way off the mark. The manufacturing process is expensive in equipment, materials and energy. The payback time before even net energy is produced over that required for manufacture for the most common solar cells is currently 3 to 4 years. Once structural support, battery storage, inverters, installation costs, etc are considered, solar panels are just not economically justified without subsidies where conventional large scale grid based electric power generation is available.--Technicaltechy 09:03, 1 April 2006 (UTC)

Merging Solar panel into Solar cell

Old comments on this moved from top of article

Should this be merged with solar panel? Rmhermen 17:10, Feb 28, 2004 (UTC)

• Definitely. I think the scientific/functional details should be under solar cell and the application and anecdotal information should be under solar panel. Another deficiency is that solar panel completely ignores those (also active solar panels whose purpose is to collect thermal energy only. -User:RatOmeter

I think the scientific/functional details should remain under photovoltaic cells because that is the proper term. Having worked as a technician making these cells I recognize that to the general public they are generally known as solar cells. However, if you think about it a photovoltaic cell becomes a solar cell when you put it out in sunlight, what if it is under indoor illumination then is it really producing solar power or photovoltaic power. It would be nice to have some discussion of amorphous cells, polycrystaline cells, single crystal cells, multi junction stacked cells, cells on glass substrates, cells on flexible plastic substrates, and the various materials, amorphous silicon, Cadmium sulfide/copper sulphide cells, zinc phosphide/copper sulfide, gallium arsenide etc...--Mmunroe 9 July 2005 07:16 (UTC)--mmunroe 06:45, 16 April 2006 (UTC)

New discussion

While there necessarily isn't a dispute yet, I have a feeling this may be the subject of debating. Simply put, solar panels are just a whole bunch of solar cells put together. All the information from the Solar Panel article can be easily assimilated into the Solar Cell article, with a neat section on panels. But if they're almost the same thing, why should they be different articles? —MESSEDROCKER (talk) 04:49, 2 April 2006 (UTC)

They shouldn't be merged, 'cos there's another whole type of solar panel - the type that heats a fluid directly. Photovoltaic panels are made of lots of solar cells, but these others aren't. Presently the Solar panel article is a bit sketchy on direct heat collection, but it's got to be discussed somewhere: some proportion of readers who navigate to 'Solar panel' will not have photovoltaics in mind at all. --Nigelj 09:59, 2 April 2006 (UTC)

So an idea is that the Solar Panel article should be divided into two; one half discussing the photovoltaic kinds of solar panels (which would link to this article) and one half discussion the kinds that directly draw h eat? —MESSEDROCKER (talk) 13:43, 2 April 2006 (UTC)

Encyclopedias are supposed to describe concepts, not words or phrases. Therefore, I think there should be one page for the concept of "device that converts radiation directly to electric current", and another for the concept of "device that traps solar radiation to heat a fluid". There could be some debate about the titles of these two articles, I admit. The first one could be "photovoltaics", and the second one could be "solar heating panel". "Solar cell" would redirect to "photovoltaics". "Solar panel", since it is ambiguous, would be a disambiguation page. What do you think? --Heron 14:50, 2 April 2006 (UTC)

I'm not too sure about renaming Solar Cell to something else, seeing as it unambiguously refers to photovoltaics. Other than that, sounds like a good plan. Let's see what the others think. —MESSEDROCKER (talk) 17:30, 2 April 2006 (UTC)

Taking Heron's suggestion as a start, the Solar panel disambiguation page would still be important as many visitors, thinking only of one use or the other would continue to use that term and head there. Having said that, I'm still not sure that the concepts of Solar cell and Photovoltaic panel are coincident. Solar cells are also used individually in low-power applications, for example to detect and measure light levels, or to power a watch or calculator. Photovoltaic panels are always concerned with efficient and cheap bulk power generation. I would vote for three articles ('Solar cell', 'Photovoltaic panel' and 'Solar heating panel') plus a disambig page called 'Solar panel' for the latter two. Existing information could be shufffled around to make all three cleanly, I think. --Nigelj 19:03, 2 April 2006 (UTC)

I'm happy with that. --Heron 20:04, 2 April 2006 (UTC)

Me too. Straw poll, anyone? (Sorry, I just like things getting accomplished quickly.) —MESSEDROCKER (talk) 20:38, 2 April 2006 (UTC)

As a scientific note of agreement with respect to the recent comment by Nigelj, a 'solar cell' is a single photovoltaic device that is used specifically to convert photons from the sun to an electric current (as opposed to light from a fluorescent lamp or laser). If you connect multiple solar cells together, you have an assembly that could logically be termed a 'panel'. Given the term 'solar heating panel' describes an analogous assembly of thermal cells, the term 'photovoltaic panel' or 'solar cell panel' sounds acceptable. I would definitely like to see the two concepts of cells and panels kept separate if possible, as the Solar cell wiki is already pretty heavy with excess content and biased with commercial plugs. Perhaps spring cleaning is in order for Solar cell? Nanomech 22:06, 2 April 2006 (UTC)

Indeed. Another thing we could do is when "Solar panel" becomes a disambiguation page, we could point out the difference between the three terms: "Photovoltaic panel", "Photovoltaic cell/Solar cell", and "Solar water heater". —MESSEDROCKER (talk) 22:53, 2 April 2006 (UTC)

I think the disambiguation idea might be the way to go. Solar panels can be thermal or PV based, serving very different needs. Cells and panels, as you say, should not be confused. Because Wikipedia articles are interlinked, I think merging too many topics on one page can be confusing, instead we could use linking features to allow readers to explore the various terms as they wish. My 2 cents. --aljo 19:17, 5 April 2006 (UTC)

I have slightly edited the "Interconnection and modules" subsection to begin this transition to differentiate "solar cell" from "solar panel". Nanomech 10:11, 9 April 2006 (UTC)

I don't think merging the two articles is a good idea. This topic is probably too big for one article. A better approach would be to divide the material so that solar cell discusses the technical details of photovoltaic cells and how they work, while solar panel discusses the application of solar technology to electricity and heat generation (this could include solar heating panels as well as photovoltaics). This provides a cleaner division of subject matter between two articles. --Srleffler 05:11, 21 April 2006 (UTC)

Well, the general consensus (at least within the discussion thus far) has been not to merge the two together, but have three articles: Photovoltaic panel (solar panel for electricity production), photovoltaic cell (very small-duty electricity production, or measuring light), and water heating panel (solar power to heat water). "Solar panel" would be made into a disambiguation page. While it was my original idea, it's not the idea anymore. —THIS IS MESSEDOCKER (TALK) 10:46, 22 April 2006 (UTC)

Solar Cell wiki needs to be edited and condensed

As a research scientist in photovoltaic materials (including silicon and non-p-n junction varieties) I would like to proprose a major change in the Solar Cell wiki page, condensing it to something representative of current research technologies (including silicon) and the science of the photovoltaic phenomenon. As I have commented earlier, there is a lot of repetition and unbecoming commercial advertisement that has made this wiki site undesireable compared to closed-source literature coverage on photovoltaics. Please, let's make a positive effort to improve the content and the organization of the wiki to make it top-notch. A good solar cell wiki improves the public relations for all of us in solar cell technologies. I have some suggestions that I would like to help implement.

Examples: Section 4: "Materials and Efficiency" -- the reference to "Materials" is repeated in Section 10 ("Current Research") and the reference to "Efficiency" is repeated in Section 7.1 ("Energy conversion efficiency").

I'm suggesting condensing text in the wiki that include the above-mentioned sections into two distinct sections to follow "Theory". These two new sections would be "Light Absorbing Materials" and "Energy Conversion Efficiency".

A "Light Absorbing Materials" section can deal with the numerous types of silicon offered today, the semiconductor thin-film assemblies like the CIGS system, the varieties of simple inorganic semiconductor absorbers that are being used in quatum dot and ETA-cell sensitized systems, the dyes that actually absorb the light in dye-sensitized cells, and the polymers that serve to absorb light in the organic polymer systems. This may contain the sprawl of silicon definitions across the wiki in the future too. While the majority of solar cells use silicon as a light absorbing material, the material itself should not serve as the definition of a solar cell.

Also, is there a better quality image of the NREL efficiency plot anywhere else? The image is low-resolution and pixelated.

An "Energy Conversion Efficiency" section would similarly contain some of the indirect adverstisements for one technology over another in the materials section. There is a significant amount of simple math for this estimation that could be included here too.

Section 6: "Theory" -- this is a fairly good section, but is unecessarily silicon-heavy. The section could be edited and simplified to reflect the science of a solar cell as a photovoltaic device and not only a "p-n junction'.

More input on the basic electrochemistry of the device would help to separate the three fundamental steps of 1) light absorption, 2) carrier generation, and 3) carrier separation. A subsection on the properties of a p-n junction is invaluable here, but this is just one way that a solar cell can function.

Section 10: "Current Research" -- this is a very messy section that appears to be essentially filled with personal and commercial plugs for specific varieties of solar cells--a very non-Wikipedian section. And I'm not confident how "current" some of the research is anymore. Not sure what to suggest for this one other than a careful inspection and slow revision.

All sections below "References"--more commercial plugs, but interspersed are a few informative links. Also requires a careful inspection, but I assume many of these links can go based on Wikipedian standards of quality.

I can only hope for the best, but I would truly like to be proud to tell people to look at the wikipedia link on "solar cells" for reliable information about photovoltaics. Thanks to all for considering my comments.Nanomech 11:13, 9 April 2006 (UTC)

If you've got the time and the energy, Nanomech, you seem very well placed to go straight ahead and make these changes yourself. WP:BB :-) --Nigelj 12:01, 9 April 2006 (UTC)

Nanomech, I agree. This article badly needs a major cleanup and reorganization. There is much redundant material here. If you have the time and energy, go for it! I agree with Anthony717's comment below, though: I don't think solar panel and solar cell should be merged. Rather, I would prefer to see one article that focuses on the technology and science of photovoltaics, and another that focuses on the application of solar technology to home energy generation (which could include solar heating as well as photovoltaics.)--Srleffler 05:15, 21 April 2006 (UTC)

Solar panel and solar cell ought not to be merged. Solar cell should focus on the technology. Solar panel should be kept as an introduction to people new to solar power. The Solar hot water article should also be kept, as solar hot water is an important industry and a very efficient technology. This wish to merge pages seems misguided. If anything, Wikipedia articles must be larger, and, when too large, be divided out into sub-articles.Anthony717 02:07, 14 April 2006 (UTC)

Solar Cell wiki Revision (April 2006)

As suggested earlier ("Solar Cell wiki needs to be edited and condensed"), and having received encouragement to do so, I have made significant revisions to the Solar cell wiki page. This is an effort to reduce text redundancy, subdue some non-wikipediean commercial plugs (both from industry and academia), and to remove overlap with the information presented also in the Solar panel wiki. However, even with the reorganisation and condensation, the wiki is still long (40kb). Hopefully we will all be able to edit it a bit more easily now. My goal is to help bring this page back to the state of a good wiki that reports the science and technology of solar cells. I have made my best attempt to arrange the sections in a logical fashion that will allow new additions for new technologies without making the page as cumbersome. Edit comments are below. Nanomech 10:30, 23 April 2006 (UTC)

Introduction

Some refinements have been made to the introduction based on the comments by the other editors in earlier discussions. There is a now clear distinction in two sentences between a photovoltaic cell and a solar cell, specifying a photovoltaic cell as a general description of a solar cell applied to solar and non-solar light. In keeping with the general concensus to distinguish solar cell from solar panel, I have also specified that a connected assembly of solar cells can be referred to as a solar panel. Redundant references to p-n junction and silicon p-n junction were edited out. Nanomech 20:35, 24 April 2006 (UTC)

The silicon solar cell image was moved down to the beginning of the second paragraph. The link was interferring with the Introduction statement that search engines report with search results. Nanomech 06:43, 26 April 2006 (UTC)

Wiki separation

It was discussed (and by "straw poll" recently agreed upon) to maintain separation between Solar cell and Solar panel. Hence the edits were performed with a page to page comparison between the two wikis. Again, I found text repetition (some verbatim) and removed as much of the overlap as possible, with directed links to Solar panel where necessary. For example, "Cost Analysis" was removed from Solar cell as it is in fact related to the cost analysis of silicon solar panels ("installed systems"), rather than being generally directed to the cost analysis of making a single solar cell.

Repetition

I have been carefully examining the various subsections of the wiki and have found numerous occasions were the text was repeated (paraphrased or verbatim) from another subsection. These repeats have now been condensed into one statement where necessary.

Theory subsection

All of the Silicon and semiconductor information in the "Background to classic solar cells" section is clearly explained in their respective wiki pages, and links have been defined for those two at the beginning of theory to supplement the reduction in that subsection. Most of the theory on Si and semiconductor physics represented here was overly-reductionist and scientifically inaccurate. This was removed and links to the silicon and semiconductor wikis are in the "Light Absorbing Materials" section.

I have also moved "Simple Explanation" into Theory as an introductory subsection termed "Simple Explanation". I have further specified two more subsections for consistency with the introduction that describe the two fundamental processes in a solar cell: "Photogeneration of Charge Carriers" and "Charge Carrier Separation".

(Sub)Section Condensation

Earlier, I suggested condensing text in the wiki that included the sections "Materials and Efficiency", "Energy conversion efficiency", and "Current Research" into two distinct sections to follow "Theory". These two new sections are now present as Light Absorbing Materials and Solar Cell Efficiency Factors. "Solar cells and energy payback" was also moved into the new "Solar Cell Efficiency Factors" section. "Current Research" remains, but has been reduced with an introduction including a ling to Timeline of solar cells that will hopefully avoid quick cut-and-pastes of recent news articles.

Applications and Implementations

"Interconnection and Modules" was moved into this section in the condensation process and the title was removed. A directed link to solar panel was also indicated here. This section was moved above theory as well.

Manufacture and Devices

This is a very well-written section that specifically pertains to multicrystalline silicon solar cell manufacture. It needs a more specific title as such. I would appreciate better suggestions than mine: Retitled "Silicon Solar Cell Device Manufacture".

External Links

A few NREL links were removed as they now point to lost web sites.

Photoelectric effect

Solar cells do not use the photoelectric effect. Solar cells are made of semiconductor material, the incoming light (photons) move electrons from the valence band across the band gap to the conduction band. The resulting electron-hole pairs are separated by the internal electrical field of the p-n-junction. In this way different charges on the two electrodes of the solar cell are created, which can be used to drive an current through a wire.

Corrected the recently modified introduction that sought to use the photoelectric effect in the solar cell definition. Nanomech 21:34, 18 April 2006 (UTC)

Agreed. Someone confused the photoelectric effect with the photovoltaic effect.--Srleffler 05:04, 21 April 2006 (UTC)

Doesn't the word photoelectric effect have the meaning of internal photoelectric effect, which also includes the PV effect? --- a reader, 21:03, 28 Apr 2006 (UTC)

The core explanation resides in the two-part requirement for the photovoltaic effect. The photoelectric effect can be viewed as a general case for the first requirement of the physical phenomenon termed the photovoltaic effect, in that the former refers to free electrons being ejected from their low energy state in a material in response to absorbed photons. The internal photoelectric effect has been used to refer to a special case regarding valence band electrons injected into the conduction band in a semiconductor. The photoelectric effect has no voice on what happens to the electrons following photoexcitation. In fact, many phenomena can follow this first step, including exciton recombination, chemical transfer of the charge carrier to a surface molecule, and trapping of carriers in defect sites. These phenomena tend to inhibit generation of electrical current due to charge separation and are considered performance reducing in photovoltaic cell research. That brings us to the second requirement of photovoltaics: the separation of charge carriers to generate electical current. Separation can be accomplished by drift or diffusion, but the charge carriers must make it to an ohmic contact and be monitored as electrical current to be considered photovoltaic. This commentary stands in contrast to the note above that "Solar cells do not use the photoelectric effect." Of course they use the photoelectric effect, but it's what happens next that separates the photovoltaic effect from the huge body of other phenomena surrounding photon-electron interactions. Nanomech 12:28, 29 April 2006 (UTC)

Conduction construction materials

I removed this from the Solar panel article:

When making solar cells for solar panels, Gallium arsenide is more efficient than crystalline silicon, but also more expensive.{{dubious}}

This article is the proper place for this incomplete information. Incomplete because those are not the only two technologies for converting solar energy into electricity. --Sunpower 09:33, 27 April 2006 (UTC)

Electrical output

I removed this from the Solar panel article:

When exposed to direct sunlight, a 6-centimeter diameter silicon cell can produce a current of about 0.5 ampere at 0.5 volt (equivalent to about 90 W/m² average, range is usually between 50-150 W/m², depending on sun brightness and solar cell efficiency).{{dubious}}

With new technology squares smaller than 6cm d. can produce about 1/2 volt. --Sunpower 09:38, 27 April 2006 (UTC)

Solar-concentrating photovoltaics

This section was removed. Although it might be misplaced here, and does need rewriting, it does look useful and should be perhaps moved to Solar power and linked from here. I'll just put it here in this box, for now, till I or someone else uses it. --Singkong2005 03:54, 5 June 2006 (UTC)

Solar-concentrating photovoltaics

- Ironically, despite the high cost of multijunction cells, they are used as part of one of the most cost-effective and promising technologies, known as solar-concentrating photovoltaics. In these systems, solar energy is concentrated several hundred times, which actually increases the cell efficiency, and reduces the semiconductor area needed per watt of power output. Many reputable sources are projecting that the cost of concentrating system will soon drop to US$3/Watt. - - For examples of concentrating systems under development, see the recent experimental "Sunflower", or the "SunCube".

It was removed because of the external links at the end being too commercial. You could add it back without the external links. Perhaps add the Wired one as a reference. Stephen B Streater 08:12, 5 June 2006 (UTC)

The modified contribution to S-C PVs was moved out of Light Absorbing Materials and into Current Research... for wiki consistency. The manner in which the post was added introduced an unsupported bias implying S-C PVs will change the face of PV technology. Solar concentrators have been around for many years, so while it is valid to mention them in this wiki, it should be acknowledged that they are not disruptive to the current technology or revolutionary. The linked Wired article appears to be more of a Public Relations plug for Bill Gross than the PV system itself. It is an example of a current application of S-C PVs, however. Modifications to the subsection were made for a clear statement, Wiki consistency, and to clarify the link to Wired (a silicon PV is used). Unsupported monetary claims were removed also. Nanomech 13:43, 8 June 2006 (UTC)

Question to Mr. Heron

Dear Mr. Heron, or how is you real name?

I wonder why do you constantly remove link to my site: www.oe-chemicals.com and even call it 'spam'. 1. I wonder for two reasons: what kind of right do you have to determine whether my link should be here or not? 2. What you so much dislike with my site? I believe, I provided a lot of useful and interesting information about organic solar cells with many scientific references that may be of great interest for the article users. 3. Or may be you want to get rid of competitor to your links, that are apparently placed here?

Please, tell me truth, and don't hide behind you fake name, Heron.

Appraciate your response,

Alexander Kel'in,

Organic Electronic Chemicals, LLC, Manager