why does a solar oven need a plastic cover while cooking?
I made a homemade solar cooker, the box type, and the site i was following instructions from told me that i should use plastic wrap or glass to cover the cooking chamber while cooking. Is that a important part for the solar oven to work?
Greetings Jessica...and thank you for your inquiry.
Is this for a school science project?
Yes,that is correct, as the site instructed you on placing a plastic or glass cover on your solar box cooker.
The reason for this is so that your solar box/oven will be able to retain the heat that builds up from the reflector panel concentration of the suns rays onto your dark cooking pot, as well as into your box cooker interior. This is what is known as "the green house effect"
Some sites suggest the use of a simple plastic cover, primarily to keep expense down, and because the cooker designs are usually not very "hot" or efficient as solar cookers and therefore will usually not melt the plastic.
If you can, it would be better and safer to use glass for your lid or cover, preferably tempered glass, but that can be a bit expensive.
If your temperatures are not going to get really high; 300 F and above, then a regular pane of glass will do, but you have to take care to avoid breaking it through use and handling.
Many people will use double pane glass for the added strength, though it is still not as durable as tempered.
Lexan, a plastic like substance, is a better alternative than plastic since it will resist UV rays, higher temps. and will not melt or off-gas like plain plastic, but it can cost a bit more money, though not as much as tempered glass.
I hope this information is helpful to you and good luck with your solar cooker.
We have many helpful pages and links on our site to help you with your homemade solar cooker needs as well as great tips and suggestions on how to more effectively solar cook.