Solar Cookers World Network

Tom Sponheim

30,964 Edits since joining this wiki
December 13, 2006

Earlier discussions have been archived.

Hi Tom,

I want to add my solar cooker design to the design website.

Sunny regards,


Hii Tom,

Thanks for getting in touch with me about my new cupcake solar cooker page. I've just put the photos in, and tried to explain the process and safety as clearly as possible. Any suggestions very welcome. This is my first ever wikihow page. Regards Helen DawsonHdawsond 12:51, November 9, 2011 (UTC)

Hdawsond 12:51, November 9, 2011 (UTC)

Parabolic solar reflectors

Hi Tom.

As you know, I have been doing some edits on the "Parabolic Solar Reflectors" page. I've added some information, and done some tidying, while trying not to be offensive to people who have used the page to document their own achievements and those of others.

I have also recently been doing some editing to the "Solar cooker" page on Wikipedia. If you compare them, you'll see some strong similarities between these two pages. In particular, there's a paragraph about Sheffler cookers which is identical in both. I wrote it, originally in Wikipedia, and figured it would be appropriate here too. Certainly, it is better than the one it replaced. Since everything in Wikipedia is public-domain, and also since I am the original author, I can't imagine that there will be any copyright problems.

DOwenWilliams 15:24, November 12, 2011 (UTC)

Hi, Dowen. I saw your edits. You have improved the page greatly. Don't worry about Wikipedia. There shouldn't be a problem. We really appreciate your collaboration. We are working to get more active editors like you.
Tom Sponheim 18:47, November 12, 2011 (UTC)

Fresnel Solar Cookers

Hi Tom:

I just noticed that you're working on a piece about Fresnel Solar Cookers. (Apparently you made a post tomorrow! It's still only 2130 GMT.)

I've never tried using plastic Fresnel lenses for cooking, but I have used them for other things. They do have some drawbacks. After a while in the sun, the plastic becomes dark and brittle. If it gets hot, it melts and deforms. Small deformations have large effects on the lenses' focusing abilities. Also, the lenses are difficult to keep clean. The ridges trap dirt.

It's a neat idea, but I think some practical experiments should be done before recommending these things to the solar cooking world.

Happy New Year.

DOwenWilliams 21:40, December 26, 2011 (UTC)

Thanks, Dowen. I agree that they are not a good idea in general. I'll use some of your concerns in the article. Tom Sponheim 03:27, December 27, 2011 (UTC)

hello tom

thank you for given the website to ease my project work. i have better understanding and many referrences are took in the sites. i will send you a copy for editing before i pass it to my lecture.

matar samba university of the Gambia

Hi. We look forward to seeing your work. Tom Sponheim 18:01, December 27, 2011 (UTC)

Editor glitches

Hi Tom:

Of late, I've been seeing some glitches in the editor while I've been making edits to the Parabolic Solar Reflectors page. I've been able to work around them until just now, when the section headings in the article have somehow got messed up, so they don't appear in the table of contents. I haven't found a way to fix this.

Can you give it a strong kick in the appropriate place?

On a related topic, is there any way to exit the editor without publishing an edit? Sometimes, when I'm experimenting with formats, I decide that I'm not making improvements, so I'd like just to cancel what I've been doing and leave the article as it was before I started. In Wikipedia and other sites, there's a "Cancel" button that I can click on to do this, but I haven't found such a thing here. Am I missing something? If there isn't such a button, could one be added?



DOwenWilliams 18:42, January 7, 2012 (UTC)

Hi, David. Can you send me a link to exactly where this error is appearing (or send pasted text?). To exit the article and throw away your changes, just click the Back button. You will see a pop-up where you can choose "Leave this page." Thanks for your edits!
Tom Sponheim 23:33, January 7, 2012 (UTC)

Ok. Here's a chunk of text I just copied from the article. This is *not* copied from the editor. It's from the article as it appears when I try to read it.. It's from near the top of the article, just above the table of contents.


One disadvantage of a parabolic reflector is that the solar energy is concentrated in a very small area, too small to be desirable for most cooking purposes. Moreover, this area moves quickly across the cooking container, unless the parabola is adjusted frequently. Parabolas with focal lengths of 1 to 3 meters (3 to 10 feet) are most useful for solar cooking. The focal length is the distance from the center of the parabolic surface to the focus. The solar image diameter is about 1/120 the focal length. For focal lengths in the range above, the image of the sun will be 8 to 25 mm (1/3 to 1 inch). As the earth rotates, the image moves 87 to 260 mm (10 image diameters) in 20 minutes.

==Rigid Parabolas==

Under this category, three major types have been identified:

Note that the section title "Rigid parabolas" is not shown as a title. The "==" before and after it should make it appear as a title, but this isn't happening. Also, this title is not appearing in the table of contents.

There are several other titles further down the article where the same thing is happening. Also, the spacing between lines is often wrong.

This problem suddently appeared this afternoon. Previously, these titles and spaces were displayed properly.

Previously, I had problems when I was editing something and tried to go into "source" mode. A pop-up appeared saying that I had made edits and not saved them, which was not true. I managed to work around this by exiting from the editor and going back in. For some reason, it worked ok the second time.

Occam's Razor suggests that there is just one thing wrong that is causing all the problems. I hope this is true!

DOwenWilliams 01:32, January 8, 2012 (UTC)

P.S. SCREAM! I showed you the error, but the damned thing corrected it *here*! Anyway, take a look at the actual article, and you'll see that that section title is shown wrongly.

DOwenWilliams 01:32, January 8, 2012 (UTC)

(i) Shallow parabolas, where the focus is outside the rim of the reflector

The problem was that the first set of equal signs was on a different line. Everything has to be on the same line like this:

==Rigid Parabolas==

Tom Sponheim 04:55, January 9, 2012 (UTC
But how did it get to be on a different line? It wasn't originally. As seen on my screen, it wasn't on a different line even after the problem appeared.
Actually, the line arangement of the whole article is thoroughly messed up. Lots of big blank spaces have appeared. Several other headings, such as "Scheffler Cookers", still appear wih equals signs, which appear to me to be on one line.
Maybe we should just go back to a previous version of the article, prior to the edits I made yesterday. Can I do that? I'm sure you can.
DOwenWilliams 16:07, January 9, 2012 (UTC)
I rolled the page back to your earlier version. You can still see your changes by following this link. You'll see your changes in red on the left. Tom Sponheim 22:17, January 9, 2012 (UTC)

Hi Tom:

You didn't go back quite far enough. I managed to go back one step further, and saved a version which looks just fine. So the article is now in good shape, as far as I can see. The edit I did after this version was originally saved was just a trivial cosmetic thing. I'm not going to invite trouble by trying to do it again!

Actually, I'm leery of doing any more edits on this article, unless something new crops up. I feel like I'm walking in a minefield. The article in its present form is pretty good, I think. I'll just leave it as it is.


DOwenWilliams 22:58, January 9, 2012 (UTC)

You shouldn't worry about editing. I've made 19k edits and I've never encountered that problem. Edit away and I'll fix anything that pops up. Tom Sponheim 06:57, January 10, 2012 (UTC)

I'll probably come back to it someday, but at present I have a strong impression that there's a bug somewhere which I'd prefer not to encounter again. When I "published" the current version of the article yesterday, the result was a mess. I managed to go back and published the exact same version again, and this time the result looked fine. What was different? I have no idea.

Do you have any way of counting how many people read articles like this? An awful lot of the information in it is very old, dating back to the 1980s or earlier, and can't have much relevance now. Also, a lot of it reflects Indian cultural priorities, heaping praise on individual people in a way that we wouldn't do in the West, and making me feel quite uncomfortable. I don't know how other readers feel about it.

DOwenWilliams 16:08, January 10, 2012 (UTC)

Hey Tom,

How are you doing. Me and my team are working hard on expanding the project to more communities in the contry. i will update my page as soon as we are done with the first phase.




Hi Tom; I just noticed that Appropedia has a nice article on Solar Cooking with kind words about this wiki.[1] Best wishes, Walter Siegmund (talk) 16:07, March 18, 2012 (UTC)

Solar ca

Hi Tom:

Thanks for getting rid of that "Solar ca" category I accidentally created.

You've probably noticed that I've edited the "Appropedia" page to include more information. I do quite a lot of writing for Appropedia, Wikipedia, and here. Sometimes, I find myself writing the same thing three times. It's better, I think, to have cross-links between these wikis, to avoid unnecessary duplication. Making users here aware of the existence of Appropedia should be helpful for everyone.


David DOwenWilliams 01:26, March 20, 2012 (UTC)

Partial translations

Hi Tom:

Just for fun, I tried looking at the automatic translations of the Parabolic solar reflectors page into other languages. I'm reasonably fluent in Spanish and French, so I wondered if the translations into these languages would make sense to me.

They're not bad, as far as they go, but they are incomplete! Part-way through the article, each translation switches into English. The rest of the article is not translated.

Maybe the translator can't cope with an article that long. Maybe it's a setting that could be adjusted.

Any hope of fixing it?


DOwenWilliams 19:01, April 1, 2012 (UTC)

I don't know of any way to adust how much Google translates. I'll do a test and see if Bing translates more of the article. I agree that the translations are pretty darn good at least for French and Spanish. I remember the Dutch and German being much rougher though.
Eventually we're hoping to make the Compendium articles somewhat shorter. We want to take out the long lists of individual cookers and make each of these articles contain good general information (like you have been adding) while still linking to individual pages about the various cookers. This should get around the partial translation problem. Thanks again for great contributions to the site.
Tom Sponheim 17:12, April 2, 2012 (UTC)
Yes. I agree that the article should be substantially shortened. At its present length, it not only causes problems with the translator, it is also extremely slow to load, and difficult to read. Much of the material ia long out of date and nowadays essentially useless. I have thought of deleting some of this old stuff, but haven't done so since the people who contributed it are still around and might be upset. Maybe they should be gently encouraged to clean up and update their contributions.
You're welcome. I enjoy doing it.
DOwenWilliams 15:06, April 3, 2012 (UTC)

Hi Tom,

i am a manufacturer of solar cooker. I just added the image of the cooker i manufacture in Cooker manufacturer - India list. But how do i add my company name in the list of manufactures and link the image with the company page to describe the feature etc of the cooker.


Subhasispaul 13:24, April 4, 2012 (UTC)

bad category

Hi Tom:

Sorry. I messed up again. At the bottom of the Solar calculations page, you'll see a category:

Parabolic cooker plans,Solar cooker plans

I thought I could add two categories, separated with a comma. Obviously, it didn't work, and I can't fix it. Help!

Live and learn.


DOwenWilliams 03:14, April 9, 2012 (UTC)

P.S. Why is Solar calculations in red? Looks ok to me.

red line

Hi Tom. Me again. :-(

Thanks for fixing that bad category.

There's still a problem with the Solar calculations page. As you see, the name keeps coming up in red. Clicking on it leads to an editing page with no content. On the other hand, typing "Solar calculations" into the "Search This Wiki" window at the top-right corner works just fine.

Any clues?


DOwenWilliams 00:46, April 10, 2012 (UTC)

If you are linking to a Category page you have to use this syntax: [[:Category:Solar calculations|Solar calculations]]
Tom Sponheim 00:49, April 11, 2012 (UTC)

Thanks a lot. It was the initial colon that was messing me up. DOwenWilliams 01:47, April 11, 2012 (UTC)

Dear Sir

I am the Founder and the Current Chaorman of the Lady fatemah (a.s.) Charitable Trust (

We are interested in solar cooker panels as wer your web site for FREE distribution to Widos and Poor Families in Iraq and Lebanon.

Please assist me where to get them and or whom to contact.

Best regards

Karim (

Missing images

Hi Tom:

I don't often scan down to the very bottom of the Parabolic solar reflectors page, so I've only today noticed that some images are missing, just above the "Quick notes" title. I guess they could have been missing for a while.

I don't think they're any great loss. They didn't add much to the article. But since they're gone. I guess their titles should be deleted too.

David DOwenWilliams 02:10, May 8, 2012 (UTC)

Feel free to remove them then. Thanks. Tom Sponheim 05:39, May 8, 2012 (UTC)


I just left a message with the events e-mail address I'm copying this to you as well.

My goal was to triple the number of people I speak to, demonstrate cooking in front of and more this year.... Solar cooking makes as much sense to me as riding a bicycle locally, its smart.

Anyway, here is the copy...

If interested in attending a hands on solar cooking build class, Ben Brown, will be offering solar cooker builds and demonstrations with the, Solar Cooking in Michigan Program, via EarthApprentice and partners this summer.

June 6, 2012, Solar Cooker Display. Hastings Public Library, Sustainability Facts and Fun at the Library, 227 E. State Street, Hastings, Michigan 49058. 269-945-4263.

July 13, 2012, Solar Cooker Build Fundraiser for GLRE. (with a later back up date in case of rain.) Great Lakes Renewable Energy, 257 N. Bridge St., Dimondale, MI 48821. 517-646-6269.

August 16, 2012. Solar Cooker Build. Pierce Cedar Creek Institute 701 W. Cloverdale Rd, Hastings, MI 49058 269-721-4190.


September 16, 2012, Solar Cooking Presentation, 11:30am-6:30pm.

Southwest Michigan Community Harvest Fest

Tillers International, Cook’s Learning Center, 10515 East O.P. Ave, Scotts, Michigan 49088 800-498-2700

Meanwhile... I'm trying to figure out what my pswrd and username is...

Shining success to you and yours and us all,

Ben Brown

EarthApprentice 03:30, June 6, 2012 (UTC)

Hey Tom,

This is Matt West.

I've made some changes to my page lately.

I appreciate having a place to share my experiments.

I hope they do someone some good.

Please tell me how many views my page has had. Or, at least, I'd like to know how to look for myself.


Matt West

P.S. The email address is no longer active.

The username PROUDMUTT is no longer active. 03:11, July 13, 2012 (UTC)

Math in text

Hi Tom:

Thanks for fixing the problem that cropped up involving mathematical formulas, etc., in the Parabolic solar reflectors page.

I notice that you (or whoever) deleted a lot of my uses of "scriptstyle". Were these the cause of the problem? I like scriptstyle. It looks nicer than simple math. I have used it a lot, both here and elsewhere, and have never previously seen any difficulty with it. But if it causes problems, please let me know and I will avoid it in future.

Thanks again.


DOwenWilliams (talk) 17:27, July 14, 2012 (UTC)

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