Windshield Shade Solar Cooker

From Solar Cooking

Kathy Dahl-Bredine developed the Windshield Shade Solar Funnel Cooker while experimenting with various designs of cookers over the past year to introduce in the indigenous communities where Kathy lives and works in southern Mexico. She hit upon an utterly simple way to make an instant portable solar oven. Taking a reflective accordion-folded car windshield shade, you can turn it into a version of the solar funnel simply by attaching little Velcro tabs along the long notched side. Here’s how:

Contents 1 Materials needed 2 Instructions 2.1 Tips 2.2 Plans in other languages 3 Variations 3.1 The "super-size" variation 3.2 The steel bowl variation 3.3 The two steel bowl variation 3.4 The Kettle Cooker variation 3.5 Armando Herculano variations 4 See also 5 External links 6 See this page on our other wikis

[edit] Materials needed

• Reflective accordion-folding car sunshade
• Cake rack (or wire frame or grill)
• 12 cm. (4 ½ in.) of Velcro
• Black pot
• Bucket or plastic wastebasket
• Plastic baking bag

[edit] Instructions

1. Lay the sunshade out with the notched side toward you, as above.
2. Cut the Velcro into three pieces, each about 4 cm. or 1 ½ inches long.
3. Stick or sew one half of each piece, evenly spaced, onto the edge to the left of the notch. Attach the matching half of each piece onto the underneath size to the right of the notch, so that they fit together when the two sides are brought together to form a funnel. (I first tried sewing these on a sewing machine, but found it cut through the reflective material.) If using stick-on Velcro, you can align the two pieces easily like this: Stick down one side of the Velcro, then press the two pieces of Velcro together, fold the shade into the funnel shape and stick down the second side.
4. Press the Velcro pieces together, and set the funnel on top of a bucket or a round or rectangular plastic wastebasket.
5. Place a black pot on top of a square cake rack, placed inside a plastic baking bag. A standard size rack in the U.S. is 25 cm. (10 in.). This is placed inside the funnel, so that the rack rests on the top edges of the bucket or wastebasket. Since the sunshade material is soft and flexible, the rack is necessary to support the pot. It also allows the suns rays to shine down under the pot and reflect on all sides. If such a rack is not available, a wire frame could be made to work as well. Note: The flexible material will squash down around the sides of the rack.

[edit] Tips

• The funnel can be tilted in the direction of the sun.
• A stick placed across from one side of the funnel to the other helps to stabilize it in windy weather (see photo).
• After cooking, simply fold up your “oven” and slip the elastic bands in place for easy travel or storage.

I have found this totally simple solar oven extremely practical, as it is so lightweight and easy to carry along anywhere. But in addition, it has reached a higher temperature in a shorter time than all the other models I have experimented with so far (I haven’t used a parabolic) - a little above 350 degrees F. I have cooked black beans in about the same amount of time as on a gas stove; I’ve used it to bake breads, granola, brownies, lasagna, all sorts of vegetables, and to purify water. The sunshade may not be available everywhere, but I suspect it can be found in most urban areas, since I found it here in southern Mexico. The Velcro was also available in fabric stores. Cost of the sunshade was about $3.00 USD; the Velcro about $.25.

[edit] Plans in other languages

• Catalan
• Chinese
• French
• Hebrew
• Persian
• Portuguese
• Spanish
• Thai

[edit] Variations

[edit] The "super-size" variation

Sharon_Cousins has come up with a super-size version made from a windshield shade cover sized for a large pickup truck or SUV. The larger size requires something on the order of a tub instead of a bucket for support. The 19" round grate from a broken fan helps hold the windshield shade in the tub and helps maintain the shape. Pots rest on a flat grate laid across the edges of the round grate, which lets a lot of light get under the food. .This cooker is vulnerable to wind, so put some weight (such as a large rock or two or three) in the tub, and if it is very windy you can also put a few foiled rocks on the grates to help hold it all down. This super-size version can handle up to a gallon of food or up to ten pounds of meat in decent sun. In really good sun, it has gotten a full two-gallon water boiler hot enough for dishwashing (too hot to put a bare hand in) in less than an hour This cooker gets almost hot enough to saute, and will get smaller amounts of food very hot very quickly. In one soup stock cooking adventure at the height of last summer, a 1 qt. cooking jar stuffed with the bones and skin of a roast chicken, some seasonings, and water with a little wine to fill, was set to cook on a glass plate under a glass cover. The contents reached a good boil and fat from the top began boiling over and out of the jar, where it not only continued to boil and bubble on the glass plate under the cover but also bubbled on the plate outside of the glass cover where it was seeping under the edge!

[edit] The steel bowl variation

[edit] The two steel bowl variation

Arnies-Solarcooking blog also came up with this variation that sandwiches the windshield shade between two metal bowls.]

The picture above was my first attempt using an 18 guage stainless steel mixing bowl and a windshield shade. I used the buckets (weighted with rocks inside) to hold the shade around the bowl. I could get water temperatures up to 150F, but not much higher. I bought the bowl at a resturant supply house in my home town.

I struggled for a month to find some way to attach the shade to the bowl... eventually I thought I need something the same shape as the bowl to easily hold it in place, hence, the second mixing bowl.

I used silver 'pinch' style paper clips to hold the ends of the shade onto the bottom bowl, and at the back where the rear view mirro depression was to help the shade conform more to the bowls.

With this design, I have been able to get 2 cups of water to a boil within an hour. Larger amounts of soup- with broth, vegetables and meat- will get to 200F easily.

I have more photos of this cooker at my blog, see link in the title of this article.

I live in The Middle of Nowhere, Texas (San Angelo) Lat: 31.38 Lon: -100.5 Elev: 1916

[edit] The Kettle Cooker variation

Converted kettle grill cooker meets the sun for the first time

View of top of kettle cooker.

Sharon Cousins built this powerful cooker from an old kettle grill. The addition of windshield shade reflector at the back makes it a very strong cooker. On its maiden flight, temperatures in the cast iron fry pan under the glass lid reached 225° F by 8:30am, 250° F by 8:45am, and by mid-afternoon it was running just shy of 325° F. The tilt angle of the reflector can be adjusted to keep the hot spot over the pan. This is a very good cooker for demos, as it can turn out a hot quesadilla or pan of nachos (slip black plates or shallow pans of nachos into the cast-iron fry-pan—use an upside down Pyrex pie pan or bowl for a lid if your glass lid is too shallow for a pile of nachos) in under ten minutes.

[edit] Armando Herculano variations

[edit] See also

• July 2006: Technical Data Sheet - Kathy Dahl
• http://texascook.blogspot.com/2008/06/windshield-chicken.html

[edit] External links

• The Terra Foundation's data sheet on this cooker

[edit] See this page on our other wikis

• See this article in French: Pare-brise ombre cuiseur solaire