The $5-$6 Solar Oven




So, a while back, being the Ecogeek that I am, I found this on

...Which is pretty awesome, because people in less privileged areas would be able to use this, as mentioned in that article. So, my friend and I decided to give this a shot...and where else better to do it than on instructables!

The only part that really cost anything for us was the glass, because we didn't have it on hand. This was bought at Home Depot and a sheet of 12"x36" was bought, which cost a grand total of $10. We only used half, so it technically only costs $5.

All the other materials are from around the office and around the house, which cost us nothing, as it was really just trash.

It's great for cooking cookies, among other things. As you will see, the glass and extra weight provides added pressure, plus the heat which aides in the cooking of the food. As always, we recommend using a food thermometer before you eat the food to ensure the proper temperature of the food that you eat to prevent food poisoning.

**Disclaimer: We do not assume any responsibility for the quality of the food nor the quality of how cooked it is. By using this cooker, you assume that all food is safe to eat and do not hold the author of this Instructable, his affiliates, & their affiliates responsible for any of your misactions.

Step 1: Step 1: Gather Materials

Materials Needed:
- 2 Cardboard Boxes at different sizes
- Scrap Paper
- Black Spray Paint
- Glass Panel
- Duct Tape
- Aluminum Foil

Tools Needed:
- X-acto Knife
- Scissors
- Glass Cutter
- Paper Shredder (Optional)
- Bricks or Canned Food
- Food Thermometer

Step 2: Step 2: Check

Make sure that the boxes are not riddled with holes or tears. Also check to see that one of the two boxes fit in the other. The top of the boxes should be level with each other, or the walls of the inner/smaller box maybe a bit shorter than the larger box. The dimensions of the smaller box should be 2-3" smaller than the larger box (ie: Larger box= Width x Length x Depth; Smaller box= (Width-2" x Length-2" x Depth)

A hole can lead to a leak in heat and in pressure which means that your food will not cook properly. If necessary, seal with duct tape and extra cardboard.

Step 3: Step 3: Shred Paper & Fill

Since we didn't have a paper shredder on hand, we tore strips of paper by hand and made them
roughly about 0.5" to about an inch in width.

Make sure that the flaps of the larger box are not folded inwards. The strips of paper were lightly crumpled together and a generous layer of about 1"-2" was placed on the bottom of the larger box.

The smaller box was placed into the larger box.

The rest of the paper was lightly packed into the sides of the box.

Step 4: Step 4: Paint

Painting the smaller box before or after is entirely up to you, but we did it afterwards and it worked just as well.

Take the spray paint and paint the inside of the inner/smaller box. That way, this aides in the radiation from the sun being absorbed by the black paint which can cook the food quicker.

Step 5: Step 5: Attach Foil

Using the duct tape, apply some loops of duct tape with the sticky side out and place on both sides of the flaps of the outer box.

Take the sheet of aluminum foil and, with the dull side down, place securely on the inner part of the flaps on the other box. That way, the shiny side will face out on both sides. Fold excess foil on the outer part of the flap and secure with more duct tape on the outside.

Step 6: Step 6: Cut the Glass

Please be very careful on this part.

When cutting the glass, depending on the size of the glass you bought, you can either measure out the dimensions to fit the dimensions of the inner box or of the outer box. Either way would work.

Cut the glass according to the glass cutting kit that you bought. Using the glass pencil, mark the line that you will cut along, using a straight edge or ruler as a guide.

It is recommended that you place the glass on a piece of cardboard for cutting.

Next, take the glass cutter and apply a firm, but gentle force on the cutter and glass. Make sure that your hand is steady and that the cut is at a steady pace. Flip the piece of glass and repeat.

Place the ball end of the cutter under the glass and apply pressure on the edges of the glass to snap the glass at your line of cut.

Step 7: Step 7: Finally...

Place the cut glass on the top of the box.

And you're done!

Depending on the weight of your glass, you can either have more weight applied to increase the pressure within the cooker. Bricks or cans of food can be used and should be placed at the corners of the box.

Step 8: The Engineering Behind It All

The different parts of the solar oven function as so:

The shreded paper functions as a type of insulation. In its place, straw can be used. The paper and straw actually also holds pockets of air which is heated by the sun. Air is preferred over metal because metal can heat easily being a conductor; likewise, heat can be lost from the metal if the external heat is not constant. The paper acts like an insulator, so once the heat is trapped in the pockets of air within the stuffing, it will not escape as easily.

The foil helps focus the sun's rays down into the box.

The black paint within the box is a demonstration of radiation. Being of black color, there is absorption of the entire spectrum of light. As light is a form of energy which is converted to heat, the food will be able cook.

The glass and bricks keep an even amount of pressure through out the box so that, in addition to the heat, the temperature in the box will also be raised as a result of the pressure applied and that builds up within the box from the sun's rays. This helps the food to cook quicker.

Be forewarned that opening/removing the glass will release all the heat that was building within the box. If checking the temperature of the food, please make sure that you are absolutely sure that it is ready to be checked, otherwise you'll have to wait again for the pressure and heat to build up again.

So, having said that, have fun and get some good food cooking cheaply!

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Participated in the
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    26 Discussions


    10 years ago on Introduction

    Nice job! I am wondering if that thermometer stabbed through the side of the boxes might give a pretty accurate reading of the internal temperature? I think it might but am not too sure how they are at taking air temperature. What do you think?

    3 replies

    Reply 10 years ago on Introduction

    I guess I should have been a bit more clear. Using a food thermometer is very specific to food. If you're cooking meat, it's something you want to use to make sure that you aren't under or over cooking it. Hitting the right temperature usually means that you're getting the right temperature to kill the bacteria and still have something edible. If you want to measure the internal temperature of the oven, however, you should be using a regular thermometer. Or, for the totally awesome engineering version, use thermocouples.


    Reply 1 year ago

    Ok guys--use an OVEN thermometer, ask your Grandma, she probably has one somewhere.


    2 years ago

    is spray paint nessecary????


    2 years ago

    Quick question. If glass is unavailable what other materials may be adequate? How would you alter the design to accommodate this substitution?

    1 reply
    IanMT IanMT

    Reply 2 years ago

    To clarify Acrylic, Plexiglass, and Lexan are also unavailable.


    10 years ago on Step 3

    Old jeans make for great installation. I am so excited to use a solar oven and this is a great design and I can not wait!!! what have you cooked in it so far and honestly how was it??!!!

    2 replies

    Reply 8 years ago on Introduction

    We made cookies the other day two years ago and they cooked in about 30 mins, using a black pan. So I'd say pretty successful?


    Reply 10 years ago on Step 3

    Unfortunately, it's been nothing but rain here in MD. But, in a couple days it should clear up and we'll keep you posted on what we cook up.


    9 years ago on Introduction

    Nice design.  I like the simplicity.
    I would like to correct one aspect of your engineering: I did a quick calc, and the weight of the glass isn't holding in any significant pressure.  I estimate the glass weighs about 5 lbs and has an area of ~200 sq in.  That's 0.025 psi.  Even if you add 15 lbs of bricks, that's only 0.1psi.

    1 reply

    9 years ago on Step 8

    I built a solar oven out of a dog house roof a plateglass window and a parabollic mirror made chicken and rice one time after ward could not get the device to cook again never regained its seal. It is important that you keep the device air tight. I will take a pressure cooker and paint it black vent it through the top of the oven and cook something I bet this would be an excellent cooker.

    3 replies

    Reply 9 years ago on Step 8

    This model will keep the oven relatively air tight. My partner in crime and I had taken this into account. Being engineering students, we argued about this using the universal gas law (dorky, I know). The Charles & Boyle Laws state that pressure will increase with temperature, and vice-versa, if the volume is held constant. The weight of the glass is sufficient to weigh down the air in the box and prevent most of the air from escaping.


    Reply 9 years ago on Introduction

    Even if the box was air-tight, any internal pressure would cause the cardboard walls to bow outward.  This increase in volume would decrease the pressure until there was essentially no pressure left.  This is why pressure vessels have rounded shapes and no corners (They are never box shaped).  There is simply no way that a box like this will contain any meaningful pressure.  Sorry.

    Yes, I'm an engineer and I understand the gas law inside and out.  PV=nRT

    Excellent instructable though.


    8 years ago on Introduction

    I have created a solar oven using WinBoard.
    Did pretty good insulation. (spent a lot of money and time as well)

    Maximum recorded temperature is 215 Fahrenheit - 101 Celsius
    I want to move it up to 250 Fahrenheit.
    I think my glass window is not air tight.

    How can you air tight a solar oven?
    Any idea???


    1 reply

    Reply 8 years ago on Introduction

    You might want to try some caulking that would be able to withstand those temperatures upwards. Or some weather seal rubber. If you're going to use caulking, I would seal it from the outside so that when you're cooking, the fumes won't affect the food. Also, keep in mind you should probably get the weather resistant caulking to prevent wear from the sun/heat.

    Hope this helps! Please let me know how it turns out!

    Try something like such:

    What does a WinBoard look like? Could it be also that your container is materially porous?


    9 years ago on Step 6

     Suggestion for cutting glass to ensure a better score mark for snapping - dip the tip of your glass cutter in automatic transmission fluid.  this will help keep the cutting wheel cool, and render less chipping of the score mark, giving you a cleaner cut which is less likely to break under a stress fracture.  If you end up picking up a more expensive reservoir cutter, ATF is the same fluid you use to fill the cutter with.

    Another suggestion is to have a finishing grade sanding sponge with you.  After you are done with your cut, lightly sand the edges of the finished glass to they are unable to cut you (this is also called seaming the glass).  This will also protect against stress cracks from a chipped edge.