Last edited: 12 January 2020
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.
Another option is reflective vinyl with adhesive backing.
Metalized polyester (MPET)Edit
The Haines Solar Cooker uses MPET (metalized polyester) film bonded to 3mm of IXPE (cross-linked polyester) foam, with a white PET film backing.
S-Reflect Mirror FilmEdit
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.
Nitrocellulose varnish layer
Polyethylene TEREPHTALATE (PET) film layer
Acrylic adhesion layer (option)
The material is available directly from the manufacturer's website.
Reflective vinyl with adhesive backingEdit
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%.
Automobile wrap mirror vinylEdit
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 61cm(24") x 152cm(60") for $7.95USD with free delivery. Chrome Mirror Silver Vinyl Wrap
Reflective material alternativesEdit
Using a white color instead of reflective sheetEdit
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 materialsEdit
- Main article: Low-tech reflective material
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.
- December 2017: Making Petals of Solar Cookers With Mylar and alveolar PP sheets - Coroplast - Elmo Dutra
- January 2015: The Effect of Thickness of Aluminium Films on Optical Reflectance - Robert Lugolole and Sam Kinyera Obwoya
- December 2001: Investigation of Reflective Materials for the Solar Cooker - John Harrison
- Low-tech reflective material
- Making the Petals of Solar Cookers with Mylar and Sheet Coroplast - Elmo Dutra
- 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