Solar Cooking
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[[File:Aluminum foil.jpg|thumb|right|300px|Aluminum foil offers a low-cost reflective material that is readily available in most cities.]]
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Standard kitchen aluminum foil can work well as a solar cooking '''reflective material'''. This common material has been, and continues to be used, in homemade solar cookers. It can be glued with white [[glue]] or [[wheat paste]]. However, a few wrinkles may result from the glueing process. Also, while the reflective surface does not get hot to the touch in sunlight, there will be some difference in expansion rates between the foil and the backing material, and this can cause some wrinkling. Typically, a little wrinkling of the foil will not create a problem with cooking.
   
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As solar cooker design continues to evolve, and provide better cooking efficiency, there is an increased interest in finding more highly reflective materials to better redirect the sunlight. Polished metal surfaces have been tried, and while effective, tend to be costly solutions. Metalized polyester film correctly bonded to plastic Coroplast sheeting is a still economical approach for users wishing to create their own reflectors. [[Elmo Dutra]], a professor and solar researched from [[Brazil]], explains one such approach in [[Media:Making Petals of Solar Cookers With Mylar and PP alveolar sheets Coroplast.pdf|Making the Petals of Solar Cookers with Mylar and Sheet Coroplast]].
   
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:{{SeeAlso|Low-tech reflective material}}
[[Image:Aluminum_foil.jpg|thumb|Standard kitchen aluminum foil works very well for solar cooking reflectors.]]The most common reflective material used in homemade solar cookers is plain aluminum foil. This can be glued very well with white [[glue]] or [[wheat paste]].
 
[[Image:Windshield_shade.jpg|thumb|right|A simple [[Windshield Shade Solar Cooker|windshield shade]] can be used as a reflector.]]
 
Solar cooker experimenters in [[Kenya]], [[Ethiopia]], [[Tanzania]], [[Peru]] and [[Bolivia]] have all found that gift wrap can be found easily that can be used for making reflective surfaces for solar cookers. Glues made from flour and water or "wheat paste" work well enough to hold the gift wrap onto the [[CooKit]]. The gift wrap is like a mirror on one side (the aluminum) and a color on the other side. So, if I can't find better information through DuPont Teijin, you might find that just shopping for shiny gift wrap is the most practical solution.
 
   
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==Materials==
[[Image:Aluminum_can_reflector1.jpg|thumb|right|300px|A funnel cooker made out of wood, using old beer and drink cans (cut open, flattened and then stapled to the wood) as reflectors]]
 
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===Metalized polyester (MPET)===
From the information I currently have, it seems that these polyester products are not suitable for lining the inside of a solar box cooker, because of the danger that at the temperatures inside the box-type cooker, the polyester would melt or at least give off foul smelling foods. I am told that this problem does not necessarily show up the first time one uses a cooker made with these materials--that it may show up after five or ten or twenty uses.
 
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The [[Haines Solar Cooker]] uses MPET (metalized polyester) film bonded to 3mm of IXPE (cross-linked polyester) foam, with a white PET film backing.
   
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===Reflective tape===
Therefore, I would suggest that the polyester or gift wrap material only be used for CooKits or for the reflectors on box cookers that are outside the box.
 
 
<table cellpadding="5" valign="top"><tr><td>[[Image:DirectTV.jpg|320px|thumb|none|This photo shows how to use a Direct TV antenna as a solar cooker using reflective tape applied in strips. Photo sent by Ranyere Bezerra.]]</td><td valign="top">[[Image:IMG_3405.jpg|350px|thumb|none|Reflective tape can be used for the reflective material on various types of solar cookers.]]</td></tr></table>
   
 
===S-Reflect Mirror Film===
[[Ravindra Pardeshi]] writes:
 
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S-ReflecT sheets laminated with high reflection PET film, on which an aluminum layer is spread by vaporization under vacuum method. The aluminum - layered PET film provides high reflection and elegant depth feeling.
   
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S-Reflect has a very high reflectence : 90% and a perfect thickness for using in every solar cooker design with or without a background.
Also note that most metals cannot be polished enough to be reflective enough for solar cooking. One exception is anodized aluminum. Metallic paints usually do NOT reflect well enough. We polish the assembled cooker of sheets. We do the polishing in two ways:
 
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{| class="article-table"
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!
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Structure
   
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Nitrocellulose varnish layer
#Professional buffing service
 
#On our own. This is very crude way but works. First we polish the surface with fine cloth and fine tooth powder and then with one localy found polishing liquid. Results are quite satisfying. For repolishing we use liquid polish only.
 
   
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Aluminum layer
==Recent news and developments==
 
*'''January 2014: Small quantities of Mylar film are offered at no charge''' The [[STEVEN Foundation|S.T.E.V.E.N. Foundation]] has generously offered to ship modest quantities of Mylar (up to 20 square feet) free of charge to anyone in USA. For larger quantities or overseas addresses, they ask $1 USD. per square foot(approx. $10 USD per square meter). They hope that people building a solar cooker or icemaker will take advantage of our offer.
 
   
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Polyethylene TEREPHTALATE (PET) film layer
==Reflective material possibilities==
 
Here is a comprehensive list of various inexpensive reflective materials that are available for solar cooker construction. [[Media:Table_of_Reflector_Materials.pdf|Table of Reflector Materials]]
 
   
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Acrylic adhesion layer (option)
[[Stephen and Sheila Harrigan]] of [[Solar Clutch]], report from Addis Ababa, [[Ethiopia]], where they promote solar cooking, that common [[Solar panel cooker|solar panel cooker]] construction materials have always been difficult to obatin. The widely used [[CooKit]] has traditionally been made from [[Cardboard|cardboard]], though recent versions are being made from [[Fluteboard|fluteboard]], such as the [http://solarcooking.wikia.com/wiki/CooKit#Poly-Furnace_variation Poly Furnace CooKit variation]. These updated cookers last far longer than the cardboard versions, which are considered to be successful if they last six months. For them however, the major problem with providing inexpensive yet durable cookers is the availability of construction materials. Cardboard is scarce, and when it is commercially available, the quality if often poor, or the product arrives torn. Tinfoil and glue can also be difficult to find. Stephen began looking more closely at what was available locally, and hit upon a product referred to as 'cool roofing'.
 
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![[File:Sreflect.jpg|thumb|364x364px]]
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|}
   
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The material is available directly from the [https://www.solarbrother.com/en/product-category/solar-reflector/ manufacturer's website].
Cool roofing is a zinc galvanized metal material, which is fairly reflective. Besides shedding water, it is also intended to reflect the hot sun from the roofs of local homes. And because of its availability, the material cost for cookers is competitive with cardboard. A CooKit can be constructed for about $6USD worth of the metal roofing. It can be cut with tin snips, and bends are made by folding the metal around a straight board. The metal CooKit has performed well, if not quite as well as the mylar covered fluteboard version, and its weight would help in windy conditions. Because the material is easily available, and can be made with existing worker skills, local manufacturing of solar cookers offers the possibility for a community business enterprise. Disadvantages include the inability to fold the cooker for storage, and transporting completed cookers will take considerable space and will be relatively heavy. The cooker edges need to be dulled or protected, as the cut metal edge is quite sharp. As solar cookers are more widely promoted and accepted, the durability of inexpensive solar cookers becomes a significant issue to be addressed. The question raised will be, is it better to offer a cooker that can be made locally, or find a way to finance the availability of cookers that are made at a more sophisticated facility, losing the empowering aspect of neighborhood manufacturing?
 
   
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=== Abrasion-resistant mirror film with adhesive backing (EverBright Mirror Film) ===
==Use the foil from cigarette packages==
 
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{{NewApr22}}High performance reflective film with abrasion resistance and anti-soiling properties to maintain high reflectance. Has self-adhesive backing with removable liner. Solar-weighted reflectance of 87% (ASTM G-173). Available as rolls on 3-inch cores. Available at [https://www.sundogsolartech.com sundogsolartech.com]
   
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===Reflective vinyl with adhesive backing===
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Vinyl sheeting with a mirror like finish is available in rolls with a self-adhesive backing, which has an easily removed protective layer. One source for this material is [http://www.solarcooker-at-cantinawest.com/vinyl_reflective_material_self_adhesive.html Solar Cooker at CantinaWest: Silver Reflective Adhesive Vinyl], who report that the material has a reflectivity ratio of 86%.
   
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Another option is [http://www.generalformulations.com/products/screen-offset-media/print-film-(1)/s2-stc-htp-90 General Formulations' printable silver polester film]
Most cigarette packages have a inner foil liner. Collect these and use them in a patchwork fashion to create a reflective surface.but do not use a package with cigarets still in it this is dangerous
 
   
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===Automobile wrap mirror vinyl===
== Mirrors made from decal/stickers ==
 
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[[File:Automobile_mirror_wrap,_9-20-17.png|thumb|Chrome Mirror Silver Vinyl Wrap|200px]]
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The same material used to wrap automobiles with commercial messages without damaging the underlying paintwork is also offered with a reflective mirror finish. While very shiny, some customers have reported it does not provide image quality reflection as a glass mirror would. Relatively inexpensive, Amazon has a link to a source with pieces 30.5cm(12") x 152cm(60") for $7.99 USD with free delivery. [https://www.amazon.com/24x60Chrome-Mirror-Silver-Sticker-Self-adhesive/dp/B00LYMX48I Reflective Chrome Silver Vinyl Wrap]
   
 
==Reflective material alternatives==
Chrome mirror sign vinyl is excellent for most solar cooking applications where the material itself is not touch the hottest part. It is made to be used on business signs and is designed to stand up to many trips to the car wash. This material can turn nearly anything into a powerful mirror. You can find it on the internet. You must use phrases like "Chrome mirror sign vinyl", or, ""Mirror sign vinyl, or Gold sign vinyl. This material is available in a self-adhesive roll. You can find short rolls or long and wide rolls. The rolls start at inchers in width to feet in width. Apply it with soapy water in the same way as window tint. After some exposure to warmth, the soap vanishes and your mirrors will stick for years. Keep them shiny with wax, oil, Scott's liquid gold, experiment with it.
 
 
===Using a white color instead of reflective sheet===
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It might be possible under ideal conditions to use a white material to reflect more light into a [[box cooker]] or as the panels of a [[panel cooker]]. The performance would suffer greatly compared to a truly reflective material, but this is worth more study. [[Tom Sponheim]] has successfully [[Water pasteurization|pasteurized water]] in a box cooker with a white inner box and a white reflector.
   
 
For additional discussion, visit [[Research#Should_the_walls_inside_the_cooker_be_foiled_to_reflect_the_light.2C_or_should_they_be_painted_black.3F|Topics needing research]].
A flexible cutting board could make a good mirror. When finished cutting the underside of the cutting board may have a mirror on it to help cook the food you cut up.
 
   
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===Low-tech reflective materials===
Think of the many shapes we have availble. Now you can turn junk into ovens and dish cookers. Here are some things I know would make terrific ovens and parabolic, and parabolic hybrids. A thermal parabolic hybrid oven will acheive temperatures hotter than needed for normal cooking, when combine with thermal cookware it is nearly dangerous.
 
   
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{{Main|Low-tech reflective material}}
It is dangerous. Be careful. It will take some time to adapt to your new abilities. A thermal griddle may be a griddle with ceramic tile in a sandwich of steel or aluminum. ALUMINUM COOKWARE WARNING: See: Aluminum Oxide poisoning. Aluminum loses heat so quickly too. I want my food cooked with glass and ceramic and steel. Matt West
 
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Reflective materials are a key component of almost any solar cooker. If you are building a solar cooker and traditional reflective materials are not available in your area, several [[low-tech reflective material]] solutions can be used as alternatives.
   
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==Research==
==Rescue blankets (Mylar)==
 
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*{{NewJan20}}'''December 2017:''' [[Media:Making Petals of Solar Cookers With Mylar and alveolar PP sheets - Coroplast - Elmo Dutra.pdf|Making Petals of Solar Cookers With Mylar and alveolar PP sheets - Coroplast]] - ''[[Elmo Dutra]]''
Rescue blankets (or space blankets) consist of a thin plastic foil (often polyethylene terephthalate, PET) and a thin layer of aluminium (cf. http://en.wikipedia.org/wiki/Space_blanket). The silver side is the aluminium side, while the gold color on the reverse side comes from a translucent yellow tint of the plastic in combination with the front aluminium layer.
 
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*{{NewNov16}}'''January 2015:''' [[Media:The Effect of Thickness of Aluminium Films on Optical Reflectance - Robert Lugolole and Sam Kinyera Obwoya.pdf|The Effect of Thickness of Aluminium Films on Optical Reflectance]] - ''Robert Lugolole and Sam Kinyera Obwoya''
 
 
*'''December 2001:''' [[Media:Reflectivematerialsreport - John Harrison 2001.pdf|Investigation of Reflective Materials for the Solar Cooker]] - ''John Harrison''
Such material is similar in cost as aluminium foil or self-adhesive vinyl stickers, large formats are common (e.g. 160 by 210 cm), and the material is indended for outdoor use. Relflective accuracy is mirror-like, in contrast to aluminium foil which has fine directional grooves in the surface from production and thus reflection artefacts. Although as with self-adhesive mirror foil, the material should not be used for the hottest part of the oven, i.e. where in contact with pot or glazing. Melting point of PET is around 260°C (500°F).
 
 
==Using the foil on the inside of Tetra Pak juice boxes==
 
===Kenya===
 
[[Solar Cookers International East Africa Office]] recycles waste from Tetra Pak materials. This is a packaging making industry and sometimes they have waste which they have already prepared, this then we use as our foil. When this is not available they buy from another packaging industry called Pressmasters Ltd.
 
Here are their coordinates:
 
Pressmasters Ltd.<br />
 
P.O. Box 17560 - 00500<br />
 
Nairobi<br />
 
[[Kenya]]
 
Fax: +254 20 823044<br />
 
Tel: +254 20 820253,820254<br />
 
Mobile +254 722514623 / 733743783
 
[mailto:pressmas@africaonline.co.ke pressmas@africaonline.co.ke]
 
 
http://www.pressmasterkenya.com
 
 
===Zambia===
 
[[Solar Health and Education Project]] (SHEP) has developed a relationship with [http://www.tetrapak.com Tetra Pak International] — manufacturer of aseptic drink containers — whereby SHEP uses Tetra Pak’s excess foil-lined paper for solar cooker construction. (The foil-lined paper is printed in wide rolls, sometimes resulting in excess material begin generated.) According to SHEP, Tetra Pak is willing to accept proposals from other nongovernmental organizations that may want to use the [[reflective material]] as long as the material will be used for workshop participants to construct solar cookers.
 
 
==Parabolic disk foiled with reflective tape==
 
 
<table cellpadding="5" valign="top"><tr><td>[[Image:DirectTV.jpg|320px|thumb|none|This photo shows how to use a Direct TV antenna as a solar cooker using reflective tape applied in strips. Photo sent by [[Ranyere Bezerra]].]]</td><td>[[Image:IMG_3405.jpg|350px|thumb|none|Reflective tape can be used to foil parabolic reflectors.]]</td></tr></table>
 
 
==Lithograph printing plates==
 
Looking for inexpensive, recycled reflective material for solar cookers? Here’s a tip from the [[SunStove Organization]] of [[South Africa]]: "Lithograph printing plates are available in every country at the government printing office, the local printer or the local newspaper. Used printing plates are sold as scrap." This scrap may be sold for the equivalent of US $1.25 per kilogram. Before using the plates in solar cookers, clean with paint thinner and water.
 
 
==CDs==
 
 
*[http://www.treehugger.com/files/2009/05/build-a-solar-cooker.php Build a Solar Cooker from old CDs] - ''Tree Hugger''
 
 
==ReflecTech Mirror Film==
 
 
A U.S. government-funded Small Business Innovation grant led to the development of ReflecTech, an unbreakable, durable, light-weight, scratch-proof, low-cost, self-adhesive, glass-free, reflective film. ReflecTech is used for the parabolic mirrors used in the solar concentrating power generation plants that are being erected in desert locations from California to the Sahara. The U.S. Department of Energy’s National Renewable Energy Laboratory has tested the latest version of this film and found it to be weatherable for over thirty years. Flexible, stick-on sheets of this mirror film could provide extremely durable, but very lightweight reflectors for solar panel, box and parabolic cookers. The silvered polymer used for ReflecTech film is guaranteed to match or exceed the structural properties of glass mirrors, at lower cost and with proven durability. For more details see the [http://www.reflectechsolar.com/pdfs/Brochure(ReflecTechPLUS).pdf ReflecTech brochure]
 
 
As of 2013, it appears the material is available directly from the company. The minimum order is 150 sq. ft. at $3USD/sq. ft.
 
   
 
==See also==
 
==See also==
  +
*[[Low-tech reflective material]]
*[[Supplies]]
 
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*[[Media:Making Petals of Solar Cookers With Mylar and PP alveolar sheets Coroplast.pdf|Making the Petals of Solar Cookers with Mylar and Sheet Coroplast]] - ''Elmo Dutra''
*[[Media:Cherly_Kennedy,_Advanced_Reflective_Materials,_3-19-13.pdf|Advanced Reflective Materials, 2011]] - ''Cherly Kennedy, Senior Scientist, Concentrating Solar Power, Advanced Optical Materials Project Leader at the Department of Energy's National Renewable Energy Laboratory''
 
*[[Media:Reflectivematerialsreport - John Harrison 2001.pdf|Investigation of Reflective Materials for the Solar Cooker]] - ''[[John Harrison]]''
 
*[[Supplies#Reflective_film|Information on the STEVEN foundation's available Mylar]]
 
*[[SolaReflex foil]]
 
*[[Mylar]]
 
*[[Ripple mirror]]
 
*[[Diamond Grade Reflective Materials]]
 
*[[Solar Oven Reflectors]]
 
*[[Solar reflector design]]
 
   
 
*[[Media:Cherly Kennedy, Advanced Reflective Materials, 3-19-13.pdf|Advanced Reflective Materials, 2011]] - ''Cherly Kennedy, Senior Scientist, Concentrating Solar Power, Advanced Optical Materials Project Leader at the Department of Energy's National Renewable Energy Laboratory''
==Using a white color instead of reflective sheet==
 
[[File:Kyoto_box.jpg|thumb|300px|none|The updated [[Kyoto Box]] cooker uses a white surface instead of a reflective surface.]]
 
   
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{{DPL|Reflective material|Reflective material|1}}
See [[Research#Should_the_walls_inside_the_cooker_be_foiled_to_reflect_the_light.2C_or_should_they_be_painted_black.3F|Topic needing research]]
 
   
 
==External links==
 
==External links==
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*[http://www.fsec.ucf.edu/en/research/solarthermal/solar_cooker/documents/reflectivematerialsreport.pdf Investigation of Reflective Materials for the Solar Cooker] - ''John Harrison''
*[http://www.reflectechsolar.com/product.html ReflecTech® Mirror Film] - a company producing reflective film suitable for solar cookers.
 
 
*[https://web.archive.org/web/20160529115423/http://www.usc.edu/CSSF/History/2007/Projects/J1207.pdf In Hot Water: Comparing the Effectiveness of Reflective Material in Solar Ovens] - ''Jasmine Griffin''
 
*[http://www.usc.edu/CSSF/History/2007/Projects/J1207.pdf In Hot Water: Comparing the Effectiveness of Reflective Material in Solar Ovens] - ''Jasmine Griffin''
 
   
*[[Lingding New Energy Co., Ltd]] sells a number of [http://lingding.en.alibaba.com/productlist-3.html reflective films]
 
*[http://solutions.3m.com/wps/portal/3M/en_US/electronics/home/productsandservices/products/ProductNavigator/TapeAdhesives/?PC_7_RJH9U5230GE3E02LECIE20KHO6000000_nid=8NBTLH65Q6beL4S7689SR8gl 3M Solar Mirror Film 1100] is designed specifically for outdoor CSP applications.
 
 
[[Category:Materials]]
 
[[Category:Materials]]

Latest revision as of 17:33, 14 July 2023

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Last edited: 25 April 2022      
Aluminum foil

Aluminum foil offers a low-cost reflective material that is readily available in most cities.

Standard kitchen aluminum foil can work well as a solar cooking reflective material. This common material has been, and continues to be used, in homemade solar cookers. It can be glued with white glue or wheat paste. However, a few wrinkles may result from the glueing process. Also, while the reflective surface does not get hot to the touch in sunlight, there will be some difference in expansion rates between the foil and the backing material, and this can cause some wrinkling. Typically, a little wrinkling of the foil will not create a problem with cooking.

As solar cooker design continues to evolve, and provide better cooking efficiency, there is an increased interest in finding more highly reflective materials to better redirect the sunlight. Polished metal surfaces have been tried, and while effective, tend to be costly solutions. Metalized polyester film correctly bonded to plastic Coroplast sheeting is a still economical approach for users wishing to create their own reflectors. Elmo Dutra, a professor and solar researched from Brazil, explains one such approach in Making the Petals of Solar Cookers with Mylar and Sheet Coroplast.

See also: Low-tech reflective material

Materials[]

Metalized polyester (MPET)[]

The Haines Solar Cooker uses MPET (metalized polyester) film bonded to 3mm of IXPE (cross-linked polyester) foam, with a white PET film backing.

Reflective tape[]

DirectTV

This photo shows how to use a Direct TV antenna as a solar cooker using reflective tape applied in strips. Photo sent by Ranyere Bezerra.

IMG 3405

Reflective tape can be used for the reflective material on various types of solar cookers.

S-Reflect Mirror Film[]

S-ReflecT sheets laminated with high reflection PET film, on which an aluminum layer is spread by vaporization under vacuum method. The aluminum - layered PET film provides high reflection and elegant depth feeling.

S-Reflect has a very high reflectence : 90% and a perfect thickness for using in every solar cooker design with or without a background.

Structure

Nitrocellulose varnish layer

Aluminum layer

Polyethylene TEREPHTALATE (PET) film layer

Acrylic adhesion layer (option)

Sreflect

The material is available directly from the manufacturer's website.

Abrasion-resistant mirror film with adhesive backing (EverBright Mirror Film)[]

High performance reflective film with abrasion resistance and anti-soiling properties to maintain high reflectance. Has self-adhesive backing with removable liner. Solar-weighted reflectance of 87% (ASTM G-173). Available as rolls on 3-inch cores. Available at sundogsolartech.com

Reflective vinyl with adhesive backing[]

Vinyl sheeting with a mirror like finish is available in rolls with a self-adhesive backing, which has an easily removed protective layer. One source for this material is Solar Cooker at CantinaWest: Silver Reflective Adhesive Vinyl, who report that the material has a reflectivity ratio of 86%.

Another option is General Formulations' printable silver polester film

Automobile wrap mirror vinyl[]

Automobile mirror wrap, 9-20-17

Chrome Mirror Silver Vinyl Wrap

The same material used to wrap automobiles with commercial messages without damaging the underlying paintwork is also offered with a reflective mirror finish. While very shiny, some customers have reported it does not provide image quality reflection as a glass mirror would. Relatively inexpensive, Amazon has a link to a source with pieces 30.5cm(12") x 152cm(60") for $7.99 USD with free delivery. Reflective Chrome Silver Vinyl Wrap

Reflective material alternatives[]

Using a white color instead of reflective sheet[]

It might be possible under ideal conditions to use a white material to reflect more light into a box cooker or as the panels of a panel cooker. The performance would suffer greatly compared to a truly reflective material, but this is worth more study. Tom Sponheim has successfully pasteurized water in a box cooker with a white inner box and a white reflector.

For additional discussion, visit Topics needing research.

Low-tech reflective materials[]

Reflective materials are a key component of almost any solar cooker. If you are building a solar cooker and traditional reflective materials are not available in your area, several low-tech reflective material solutions can be used as alternatives.

Research[]

See also[]

  • Advanced Reflective Materials, 2011 - Cherly Kennedy, Senior Scientist, Concentrating Solar Power, Advanced Optical Materials Project Leader at the Department of Energy's National Renewable Energy Laboratory

External links[]