Instructables

Best Solar Oven

Picture of Best Solar Oven

In my Engineering class, my teacher told us that we had to invent or modify something and post it on the Instructables web site. I looked at three or four solar oven, and using their findings and ideas, I built the Ultimate SOLAR OVEN!  

This Solar Oven is very cheap and easy to make.  It uses around-the-house items that you use every day.  

I hope you enjoy my solar oven.

Ben G.
 

 
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Step 1: What you need!

Like I said, almost all the items are things you find around you house.  You will need...

-1 big box (You probably want it to be a square box that is bigger than 2 feet long)
-1 small box  (It should also be square and 4-6 inches smaller than the big box)
-Styrofoam insulation (you can cut it up to fit in the big box)
-Tinfiol
-Black spray paint
-Newspaper
-Glass (One person used glass from a broken scanner.  It will need to be big enough to cover the box.  You can also buy a sheet of glass and use a glass cutter to cut it so it has the right dimensions.) 
-Tape or glue
-Glass cleaner
-Pare towel
-Sharpe (who says it can't be pretty)
-Thermometer
-Baking rack (optional)
-Timer (optional)
-If it isn't sunny, you can try a very bright light.  It probably won't work as well.

Once you have gathered all the materials, you may go on to the next step...
 

Step 2: Paint and Dry

Picture of Paint and Dry
First, you must go out side with your small box and paint the bottom of the box black with your spray paint.  DO NOT breath in the fumes!  Depending on you paint bottle, it should dry in 15 minutes.

Step 3: Tinfiol in the Small Box

Picture of Tinfiol in the Small Box
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After the small box is dry, bring it back inside.  Then use the tinfoil to cover the 4 sides.  It should look like the picture below.  You must use the shiny side of the tinfoil.  Also, it is better if you use see-through tape.
Ev4 years ago
Doesn't make sense to paint it black then cover with aluminum foil. I say skip the painting step. You DO want to put black cooking pots in it to convert the light energy into heat. Solar cooking recipes even say you can bake a potato by putting it in a black cotton sock!

It may not seem to make sense when you first think about it because visible light can't pass through aluminum, but keep in mind it's not the visible light that's cooking the food, but the infrared light, what we commonly refer to as heat. Aluminum is a good conductor of heat, and hence the heat travels to the other side of the aluminum and is absorbed by the black surface. Black surfaces absorb both visible and infrared light. The heat absorbed will slowly radiate back out, increasing the temperature in the oven. You can set up an experiment to test this out, by making two ovens, one with black material under the foil, one without, and checking the temperature of both to see the difference.

lbuchholz3 months ago

why not try smoothing he edge with a high heat blow torch used in glass blowing.

it softens the edges once it cools so the rough shards are removed. you can tape after for added safety or leave the UN-burry pieces in place. or just re enforce the corners where sharp (if you can find a way to punch a hole in glass, a couple handles may be a nice addition)

Tihomir G5 months ago

I have an idea to put copper plate painted black on the bottom of the small box. The copper plate will warm up by the sun rays and in contact with the dish where the meal is it will transfer the heat to it. Copper is one of the best thermal conductors.

RadiantLux4 years ago
Your next step will cover the box with foil. Why do you need to paint it? I would rather not add the toxins to m y oven. Does it make a difference?

Using black illustration board is better as spray. You also can make a small frame at the bottom and put there small stones or a big tile. Those stones keep the oven longer warm. Make sure the small stones are level. Any way a good presentation.

I live in the Philippines and the angle for the reflectors I use is 67 degrees. I try different angles but 67 work it best.

I also use duck-tape to cover the glass and after more as a years it is still OK. No problem if it is hot.

radiant good call. the box doesnt have to be black, my first cardboard cooker i used a black t shirt, ( i too dont like toxins and being a painter i know what nasty things are in them ) you can use reflective material inside, the side effect is that the oven will not get as hot standing alone with no cookware. if however you add a nice piece of black cookware you get good heat. elevate the cookware a bit off the bottom for optimum performance.
I don't think that you are supposed to put foil on the bottom... but the black in the photograph looks rather grey :/
you Put the Paint At The Bottom To Hold Heat Nice Idea Ben112
hefner934 years ago
may i have the recipe you used for the cookies for this oven i might be making this for a physics project and do you know how long it would normally take to bake them?
lol physics project !! worried about recipe hahah!!!! funniest thing i heard all day

just BURN SOMETHING mwahahaha PROOF OF PRINCIPLE :)
Double your cooking time just remember to keep a check on them so they wont burn.
sxu12 years ago
How long did these cookies take to bake? Please respond!!!
penasagra3 years ago
To keep the flaps in the right position you could join the flaps using either pastic tape (ideally duck tape) or a string set to the right distance.

When the flaps try to fall down, they'll be stopped by the string and will remain at 45 degree angle.

Not very useful if there's wind but...

I hope it helps.
Duct tape will release if made to sit in the sun for a long time. The stuff, in my opinion, is useless. The tape you should use is called Gaff tape. Theater set construction crews swear by it as do I. It can be applied and reapplied many times.
Ballabirdie4 years ago
@RadiantLux You need the black paint in a solar oven because the color black absorbs light (and therefore, heat) and is essential to make the oven hotter. You could probably find some non-toxic black spray paint, if you are willing to look for a while.
Tempura paint, or child-safe or barbecue grill paint as long as the label reads non toxic when dry is what is needed.
i c monkey3 years ago
don't put foil on the bottom of the box
You can *not* use styrofoam for insulation in a solar cooker! They give off toxic fumes! Read the Introductory Manual at htttp://www.solarcooking.org under Solar Cooking: The Basics to find safe alternative ways to insulate your cooker. Then see how you might improve on some of the existing designs. Good luck!
Tannius4 years ago
 What is the average temperature inside the over? I'm guessing 450 degrees isn't even close other wise the cardboard would combust, also the reason you said to double cooking time.
Ev Tannius4 years ago
I have a manufactured sun oven from http://www.sunoven.com/. It can get to 400f in the summer time. It's an even heat, not like a gas or electric oven which has hot spots. I use regular cooking times. There are some solar recipes on the internet. There are a LOT more crock-pot or slow-cooker recipes that adapt very well to solar cooking.
Lawst4 years ago
To position the reflectors and hold them in place use sticks. Either tape them into position or stick them into the ground at the height you need.
sarahann8264 years ago
does the glass go on the very top of the box on the inside, or does it go on the bottom under the rack? I didn't understand that part.  Love the idea and will definitely try this.  Thanks.
thisismin34 years ago
is it possible to use a substitute for black spray paint, such as dark blue?
ben1122 (author) 4 years ago
Solar ovens are much better for the earth, and you can save money and energy (electricity)!