Talk:Solar energy

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Good article Solar energy has been listed as one of the Engineering and technology good articles under the good article criteria. If you can improve it further, please do. If it no longer meets these criteria, you can delist it, or ask for a reassessment.
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To-do list for Solar energy: edit · history · watch · refresh
  • Reduce size of article. Major trimming needed. Goal should be 30 to 40 kB edit byte count.
  • See Wikipedia:Peer review/Automated/May 2008#Solar energy, for some automated suggestions.
  • Add resources for people who want to use solar energy, to help stop global warming
  • Replace book page references with web page references where possible.

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Copyedited by Adacore (talk) – 18:18, 13 June 2008 (UTC)
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[edit] Short paragraphs

  • The batteries of electric bicycles may be charged from solar-generated electricity; alternatively a PV panel may be located on the bicycle itself.

The idea of solar-generated electricity powering vehicles could go into an introductory blurb. The vehicle section might need one anyway because we need to be more explicit about the experimental nature of solar vehicles.

see Absorption refrigerator Mrshaba (talk) 00:43, 3 June 2008 (UTC)
During 2006/2007, solar assisted cooling attracted increased interest for a variety of commercial and industrial buildings; some dozens of large-scale systems (i.e., 100–500 square meters) entered service in Europe, mostly in Germany. Sarasin (2007) reported around 40 systems in service in Europe solar-assisted air conditioning of buildings, with total capacity 4.4 MWth. See IEA/RETD (2007) for a comprehensive report on the subject. Mrshaba (talk) 23:13, 23 May 2008 (UTC)
  • Concentrators can be used in the gasification of feedstocks such as coal, municipal solid waste and crop-grown biomass. The resulting hydrocarbons can be used to synthesize so-called "sunfuels".
This blurb can be merged into the S2P blurb somehow.
  • Concentrating solar technologies can also be used in the production of industrial chemicals. A prototype 10 kW solar furnace at the Paul Scherrer Institute produced lime at 64.2 g per minute with a solar energy to chemical energy efficiency of 34.8%.[2]
The process heat section should mention solar furnaces. This info can be trimmed and used as one of a few example there.Mrshaba (talk) 16:58, 14 May 2008 (UTC)
  • A food processing facility in Modesto, California uses parabolic troughs to produce steam used in the manufacturing process. The 5,000 m² collector area is expected to provide 4.3 GJ per year.[3]
The blurb could be expanded by mentioning some other solar trough process heat projects and giving a basic explanation of operation.
Rough draft doneMrshaba (talk) 20:23, 20 May 2008 (UTC)

[edit] Other SE pages

Orange sun.
Orange sun.
  • Nine out of ten solar energy sites have a picture of the Sun on the home page or a Sun icon is used to represent the institution itself. Interestingly, the Department of Energy seal has an oil derrick, a wind mill, an atom, what looks to be a turbine and the Sun positioned top left. Classic books on solar energy and alternative energy such as Soft Energy Paths, A Golden Thread, Direct Use of the Sun's Energy, The Coming Age of Solar Energy, The Solar Fraud, and The Passive Solar Energy Book all have pictures of the Sun on the cover. Solar energy technologies are diverse from building design to PV. There's good reason to put a PV picture in the lead because it is growing so fast and produces high quality energy. Then again solar water heaters produce 10 times as much energy as PV and 80% of the growth is unsubsidized. And why not solar design which is ancient and still tremendously useful today. The page is about many technologies all of which are Sun technologies. If the lead is supposed to summarize the page I think a picture of the Sun is appropriate. Mrshaba (talk) 20:41, 26 May 2008 (UTC)
    Do you really expect me to believe that a book titled "The Solar Fraud" is about solar energy? That wasn't a good one to include in your list. This isn't a coffee table book, this is an encyclopedia. Stick to the subject. I do agree that there is good reason to put a PV photo in the lead - it's the fastest growing source of energy. Solar water is tremendously cheap, but outside of Israel it isn't very popular. It is decidedly unpopular in the US. Which is very odd. 199.125.109.134 (talk) 09:11, 3 June 2008 (UTC)
China added around 15 GW of rooftop solar water heating capacity last year. Cypress and Israel are per capita leaders in the use of solar water heating but China has about 65% of the world market. This technology will spread like a wildfire and it won't seem odd anymore. And yes, The Solar Fraud is about solar energy... Reading Haydens's bashing of solar energy in The Solar Fraud is a bit like reading about nuclear capacity factors in Soft Energy Paths. Playing with statistics does no good. Mrshaba (talk) 02:43, 14 June 2008 (UTC)

[edit] Moving and removing content

This section has been set up to discuss and propose moving content off the page. Mrshaba (talk) 15:41, 21 May 2008 (UTC)

Just do it. No discussion needed. Just leave a summary in the main article and copy it to the subarticles. Just don't delete anything. It helps if you do the copy before the delete because this is a high trafficked site and you don't want someone clicking on it and at that moment not finding what they are looking for. Better to for a few seconds have a duplication of information than for a few seconds/few minutes have information missing. 199.125.109.43 (talk) 18:33, 21 May 2008 (UTC)
  • Daylight saving time (DST) utilizes solar energy by matching available sunlight to the time of the day in which it is most useful. DST shifts electricity use from evening to morning hours thus lowering evening peak loads and the higher costs associated with peaking electricity. In California, winter season DST has been estimated to cut daily peak load by 3% and total electricity use by 12,250 GJ.[4] DST has been estimated to reduce early spring and late fall peak loads by 1.5% and total daily electricity use by 3,600 to 11,800 GJ.[4]
I calculated the effect of DST on California and came of with 553 GWh out of a total of 283,000 GWh of electricity consumed annually. I had thought the number was closer to 1-2% of electricity consumption rather than one-fifth of one percent. The DST paragraph was also questioned by the peer review. I added this information originally but now I think it needs to go. Any objections? Mrshaba (talk) 21:47, 30 May 2008 (UTC)
See revised blurb and comments below by Eubulides. Mrshaba (talk) 16:56, 6 June 2008 (UTC)

I think CSP needs to stay. These are some of the oldest and most industrialized solar technologies. They are important to the weight and balance of the article given their history and current development. The CSP technologies are covered in more depth in the Solar thermal energy article. In my opinion a sub-article covering these technologies specifically should be called Concentrating solar thermal (CST) or Concentrating solar power (CSP) per their general naming conventions. The page is currently about 41 kb of readable prose. This length does not require breakup. See Article size Mrshaba (talk) 16:56, 6 June 2008 (UTC)

Please don't bite the newbies. This article needs more than one editor, more than two, more than ten. Please don't revert just because someone makes a good faith edit.[1] You think there is any chance of someone helping with the article when they get treated like that? The material removed is covered in the subarticle and does not need to be duplicated here. There was nothing wrong with the edit, and it certainly helped with the size. When you are on dialup, which last I checked was true of at least half of the world, edit byte count is far more important than readable prose. In any case 41 kb is pretty long for readable prose. It is better to use summary style, which is just what you reverted. Apteva (talk) 11:57, 7 June 2008 (UTC)
As you know, the edit byte count argument has been rejected on the Article size talk page and it doesn't need to be carried on here. I'd like you to drop this argument and remove your call for major trimming. It is fair to ask for discussion before moving and removing several paragraphs. FA articles are thorough and CSP is an important technology that deserves inclusion. Summarizing the individual technologies in 4 or 5 sentences seems to give them proper weight. Mrshaba (talk) 19:56, 7 June 2008 (UTC)
The best way to include it is just to introduce it and make a {{main|Subarticle}} link to it. Articles should not attempt to pull everything out of subarticles and put them into the main article, but instead should do the opposite, pull things out of the main article and put them into subarticles. Which is better a 10 megabyte main article that has links to 100 subarticles that are each 100 k, or a 10 k main article that has links to those same articles? In both cases the exact same information is presented. In the first case it is all duplicated and the main article is impossible to open, in the second case the main article opens in about a second and can be quickly used to find the detailed information in the subarticle. The reason why Wikipedia has chosen the latter, known as summary style, is that it works better for an encyclopedia, where many people are just looking for one factoid, and do not wish to read the entire article. Apteva (talk) 15:17, 10 June 2008 (UTC)

The 4 or 5 sentence blurbs are good summaries. These concentrating technologies specifically deserve to be mentioned on this page because they produce utility scale electricity and have for a long time, they show different reflecting geometries that aren't mentioned anywhere else on the page, and they have wonderful pictures which add to the quality of the page. The material has been here for many years so there have been many thousands of page visits without complaint. Your desire to break up this article is a desire seemingly separate from the article itself. You seem to be looking at it from an information management point of view rather than a content point of view and I think you've got it backwards. The content should show you how to manage the information. The size of the article is just about right. Mrshaba (talk) 17:12, 10 June 2008 (UTC)

You are entirely entitled to your point of view, which I believe is based on viewing it from a broadband account and not from dialup, which is 25 times slower. I am not advocating that the article be 25 times smaller, however, only 2 times smaller. I have no objections to a few sentences about an important technology, although the approach should have been to revise the summary and not just revert it.[2] The intent is to summarize the entire subarticle, not every portion of it. I really can not see the need for subsections in summaries. Apteva (talk) 19:17, 10 June 2008 (UTC)

[edit] Moving and removing content (Post Adacore)

Adacore trimmed, truncated, and/or moved some detail oriented info. Following this mindset I'm moving similar info here.

  • A molten salt storage system consists of a salt loop connected to an insulated storage tank. During the heating cycle, the salt mixture is heated from an initial temperature of 290 °C up to 565 °C. During the power cycle, the salt is used to make steam for a thermal power station. Mrshaba (talk) 03:27, 14 June 2008 (UTC)

I plan to replace/alter this info. The basic issue here is that unsubsidized PV electricity is more expensive than conventional electricity in all but remote areas or island markets such as Hawaii and Japan. We can mention grid parity locations but we should not exaggerate the economy of PV. Per Adacore's suggestion, I plan to add a table that lists levelized costs of PV in comparison to other energy technologies. This value will not include subsidies, incentives etc. Preliminary research indicates the value will be around 20-40 cents/kWh.

  • Photovoltaic electricity is now competitive with conventional electricity rates in many locations. Due to sale of renewable energy credits and other incentives, Nellis Air Force Base is obtaining photovoltaic power for about 2.2 cents/kWh and grid power for 9 cents/kWh.[5] Typical payback periods for installing photovoltaics are 15 to 25 years.[6] Photovoltaic production growth has averaged 40% per year since 2000 and installed capacity reached 10.6 GW at the end of 2007.[7] By 2006 more polysilicon was used for photovoltaics than for computer chips.[citation needed] Mrshaba (talk) 04:05, 14 June 2008 (UTC)

[edit] Order of mag error in wordlwide electricity gen.

NB: This change needs to be made by someone with enough privileges to edit. I have no access to change this page.

The source [12] gives the figure of worldwide electricity production of 15746.54 billion kWh. Since 1 kWh = 1000 W × 3600 s = 3.6×106 J, the figure in question is 15746.54×109×3.6×106 = 56.68754×1018 J, or 0.05668754 ZJ. The article lists 0.00567 ZJ, which is one order of magnitude less, and needs to be changed to 0.0567 ZJ.

I also confirmed that worldwide energy consumption per [13] is right. I did not compare any other figures in the article to those in its sources, however.

— Fregimus (talk) 09:05, 31 May 2008 (UTC)

That error was made by Mrshaba with this edit.[3] 199.125.109.31 (talk) 13:57, 31 May 2008 (UTC)

{{editprotected}} Please change 0.00567 to 0.0567 in the Energy from the Sun section. 199.125.109.31 (talk) 14:03, 31 May 2008 (UTC)

Please also unprotect this page so that we can edit it ourselves. The page was inappropriately protected to allow one editor to edit and not another. 199.125.109.31 (talk) 14:04, 31 May 2008 (UTC)

Good catch. Mrshaba (talk) 19:05, 31 May 2008 (UTC)

Only half done. The page is still protected, and needs to be unprotected. 199.125.109.134 (talk) 08:48, 3 June 2008 (UTC)

[edit] Daylight saving time

I was asked to look into daylight saving time and its relation to this article. I just now saw the text in #Moving and removing content and have the following thoughts:

  • That study is old (2001) and its conclusions are dated. I suggest the following more-recent citations:
  • For more studies and details, please see Daylight saving time#Energy use.
  • It's probably overkill to cite all this stuff here. Aries & Newsham is the best citation, since it's a review (not just a single study). To help try to improve things I made this change to incorporate its results. Hope this helps.

Eubulides (talk) 05:34, 3 June 2008 (UTC)

[edit] Images

If you would like to propose an alternate image, be my guest. However I do not know of one that does the job as good as the ones used. As to discrepancies, I see none. The article adds surface radiation of 89 PW to atmospheric absorption, 33 PW, to get 122, which is converted to 3850 ZJ. 33 PW is not inconsistent with the 870 TW that the wind includes. You want to explain your confusion? What you are doing in the article, however, is jumping around a lot between total energy for the sun and potential energy from the winds, which is totally comparing not only apples and oranges, but ripe apples with rotten oranges. If you would like to switch to other images, just remember the guidelines, one that shows an earth based application of solar energy, and one that shows the potential for solar energy. Apteva (talk) 00:05, 4 June 2008 (UTC)

The box lists a flux of 86 PW. The page lists a flux of 89 PW. Mrshaba (talk) 01:49, 4 June 2008 (UTC)
Well that is hardly an order of magnitude. If you look at the reference you will see that the older version used 89 and the current version states that it gets updated as assumptions change. 199.125.109.136 (talk) 02:16, 4 June 2008 (UTC)
89 PW in one place and 86 PW in another is a discrepancy. Energy vs exergy is the discrepancy that underlies all of the information in the box diagram vs the page. The wind flux listed in the box is off by an order of magnitude from the wind potential listed on this page and the wind power page. The external ref listed for the box diagram blurb is also dead. The box diagram has already gone through an RfC which favored removing it for a higher quality picture. I've let it slide for the most part because I'm sure as the page makes the run to FA these things will work themselves out. Mrshaba (talk) 03:05, 4 June 2008 (UTC)
You have a major discrepancy in listing 3850 ZJ for solar and 2.25 for wind as one is total flux and the other is available potential at a specific height and location. I was just going to remove the wind line item, but figured if it shows the height it was for readers would get a clue that it doesn't include the jet stream for example, which is included in the 870 number. There is nothing wrong with the cube figure, it's a good image - every time you take it out someone else puts it back. You are splitting hairs over things that are a mile wide. It's pointless. Apteva (talk) 03:36, 4 June 2008 (UTC)
The immediate problem with the box is that it conflicts with information on the page - both text and the other diagrams with stronger corroborating sources. As to the discrepancy, each bullet is given in context with a source. Smil and NASA use similar fluxes. There is no way to compare everything symmetrically. Primary energy use does not compare 1:1 with electricity generated from wind or PV. These things are beyond the scope of this page. Mrshaba (talk) 05:26, 4 June 2008 (UTC)

You need to be specific about what you are talking about. 86 and 89 and not significant differences. Neither is a number that is usable for any real purpose. Does it matter that one indicates that we only need to use 0.0174% of available sunlight to power all our needs and the other that we only need 0.0169%? Not in the least. Intelligent people simply round it up to "less than 0.02%". We can easily harvest that or ten times that if we wish, or even 100 times. What you need to understand is that earth science is an approximation, it is not an exact measure; when we calculate how big a mountain is (not how tall but how much mass it contains), it doesn't matter if we are off by 5%, 10%, or even 20%, because no one is ever going to use the number anyway. Our job is not to look for exact numbers, but to report things as they are represented by available references. If someone in 2006 says 89 and someone in 2008 says 86 the best thing to do is show the source for each and refer to the number as approximate, which is exactly what has been done. You need to get over wanting everyone to use the same number for everything. Estimates vary, just leave it at that. By the way, solar can be expected to take an ever increasing bite out of primary use, as people switch from gasoline and diesel cars to plug in hybrid and electric cars, and as people switch from oil and natural gas heat to solar/electric heat in buildings. I would estimate that if the Chevy Volt or next gen Prius had a 40 mile electric range the only time most people would use any gasoline at all with them would be on the occasional weekend that they went away on a trip - for many only once or twice a year. Since the equivalent fuel cost of electricity works out to about $0.60 a gallon I would expect at that point that gasoline will drop to about $0.90 to remain competitive. It's all supply and demand - if there is no demand but plenty of supply, the price drops. If you have a car that you can fill up with whichever is cheaper, you wouldn't buy gasoline if it was more than about that price. Apteva (talk) 17:26, 4 June 2008 (UTC)

The box lists a flux of 86 PW. The page lists a flux of 89 PW. Congrats on getting an account. Mrshaba (talk) 17:55, 4 June 2008 (UTC)

Read the above. Who cares? Use the older Image:Available Energy-2.jpg if it matters that much to you. The newer one is much better, though, because it also includes geothermal, and all the numbers, for solar, wind and geothermal are all from the same reference. Apteva (talk) 21:51, 4 June 2008 (UTC)

I don't think either picture belongs on the page let alone the lead. This picture went through a two month long RFC from October-December 2007 and has gone on well past long enough since then. SEE: Rfc Pictures. Consensus was to remove the picture. This has been an incredible waste of time and effort. Mrshaba (talk) 19:58, 6 June 2008 (UTC)
Sorry to hear you so disappointed. Actually this is an important article that gets over a million page views each year, and on a topic that is becoming more important every minute. Solar grid connected PV is the fastest growing energy source in the world, and is an incredibly important replacement for dwindling oil supplies. Solar grid connected PV can easily replace home heating oil, automobile fuel, etc. In conjunction with wind power and hydro-storage, solar energy can easily meet all of our energy needs, 80% of which are currently met by oil. Oil which is selling at 5-6 times cost due to it running out soon. Just like the lemmings we came to a cliff and went right on over it, even though the solution was seen and the problem known thirty years ago, just as the dual problem of global warming was known thirty years ago. Another clue of the importance of this article is that it also exists in over 40 other languages. So no it has not been an incredible waste of time. However, to properly illustrate the article, the two lead images should be one that shows a typical application of solar energy and one that shows the potential for solar energy, which is just what we currently have. However it would be a huge improvement to replace the U.S. centric photo with one from one of the larger European solar power plants. Unfortunately we do not have any. Apteva (talk) 11:39, 7 June 2008 (UTC)
The Rfc indicated the box picture is undesirable for several reasons. There were 5 or 6 people that indicated negative views of the box diagram with you as the sole supporter. This is an ILIKEIT issue. Drop it. Mrshaba (talk) 15:38, 7 June 2008 (UTC)
No, it's an it makes sense issue. You might notice that during your wikibreak no one but no one objected to the lead images after they were restored, other than to tweak the size a little. Also, I took a look at all 45 sister language pages today and the vast majority use an application and/or an indication of the availability of solar energy. See for example de:Sonnenenergie and ca:Energia solar which used both. There were a few with none and a few that just used whatever we were using when their page was created. One used sort of a global warming diagram, and another used the spectrum of sunlight. So I fail to see any reason to deviate from what is most practical, and most popular for that matter - an image of an application and an image showing availability. Apteva (talk) 07:57, 8 June 2008 (UTC)
I'd suggest RfC except it's already gone to RfC. What's the problem with the picture of the Sun? Why are we making a big deal out of this? Itsmejudith (talk) 18:12, 8 June 2008 (UTC)

The sun doesn't illustrate the topic. Using it would be fine if there were no images available that actually show solar energy. As it is the commons category has 120 images and 20 sub-categories in all. Countless images that do illustrate the topic. We used the sun a couple of years ago but have gotten away from it now. Apteva (talk) 04:23, 9 June 2008 (UTC)

Er... Only a picture of the Sun shows solar energy, to the extent that one can show energy. Other photos show some ways that people use solar energy. It's entirely appropriate to start with the general and then move onto the particular. Itsmejudith (talk) 09:00, 9 June 2008 (UTC)
Isn't that what this article is about, the ways we use solar energy? Discussion about the actual energy of the sun are contained in other articles, such as sun and nuclear fusion. We didn't create the sun, but we did create solar energy, in the form of photovoltaics and many other applications. It is a broad topic, but there are iconic images that can be used, such as solar two (now decommissioned, oddly enough), or a large photovoltaic power plant. I would love to have someone take a photo of one of the larger photovoltaic plants. Over the next few years these will be in the hundreds if not thousands of megawatts, although thousands of megawatts is like trying to take a photo of a forest - you lose sight of the trees - closeups of SEGS are more effective than overhead views. Apteva (talk) 16:49, 9 June 2008 (UTC)

[edit] Looking for levelized cost of solar water heating

The solar water heating blurb needs an estimate of price/kWh. This only one I've found comes in at 7.25 cents/kWh.FSEC —Preceding unsigned comment added by Mrshaba (talk • contribs) 23:02, 9 June 2008 (UTC)

Found and added prices for US. China is much lower but I do not have a source. Mrshaba (talk) 18:53, 11 June 2008 (UTC)

[edit] Comments from copyedit

I've just completed a complete copyedit of the article, and have a few comments (which I've listed on the WP:LOCE copyedit request page, but thought it would be useful to include here also:

  • The myriad of subarticles on solar cells and photovoltaics, especially with regards to spacecraft and satellites, is very confused and needs to be attacked by someone with a clear plan of how the subject should be broken down and structured. In editing the article I found Photovoltaics, Photovoltaic array, Solar cell, Photovoltaic module, Space solar power, Solar power satellite, Solar panels on spacecraft and a few other relevant articles, none of which contained all the information found in the Photovoltaics section of the Solar Energy article. Some of there are obviously necessary, but I can't help but feel that some of them could be combined to give a more streamlined division of information.
  • With the costs per kWh given for solar energy, some comparison to "traditional" power source unit costs (for example for coal or other fossil fuels) might be useful for context (unless it's there already and I just missed it).
  • The scope of this article is so broad I think it probably merits its own WP:WikiProject. Many of the sections could probably be ruthlessly trimmed, but only once pages suitable for the displaced information are available. This is already true in some cases (and I tried to move some information to subarticles where this was the case).Adacore (talk) 18:23, 13 June 2008 (UTC)
Also, there's still a fair bit of duplication in the article, especially in the photovoltaics and development, deployment and economics sections. I may take another look at this and try to sort it out. Adacore (talk) 18:31, 13 June 2008 (UTC)
The scope is indeed broad but that's part of the appeal of the page. It has been difficult to condense things down and still show some relevant connections between historical and current development, other energy technologies etc. The 10% you shaved off with your ce definitely helps. I wrote the PV section with those extra details mostly because more people are interested in PV than other solar technologies on the page. That's a good idea about comparing costs so I'll make up a simple table in the DDE section with levelized costs for coal, NG, hot water, PV, and CSP. The DDE section is the most recently completed part of the page so there are doubtless some things that can be moved around. Mrshaba (talk) 01:51, 14 June 2008 (UTC)