Best Solar Oven





Introduction: 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.

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)
-Black spray paint
-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)
-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

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

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.

Step 4: Insulation

While the spray paint dry's, you can work on the main part of the oven.  The insulation is what keeps the oven warm and that is what cooks the food.  Because the insulation is sooo important, I used two different kinds of insulation. 

The first kind was the syrofoam insulation.  I used half inch white stryfoam plate.  I then cut them down to the length of you box.  I should surround all 5 sides with no cracks.  It is okay if there are cracks, but try to make sure there aren't any.

The second kind of insulation is newspaper.  Place the small box in the bigger box.  If the dimensions are good, there should be 1-2 inches on all sides of the boxes.  Crumble the used pieces of newspaper and stuff them in the area.  Make sure there are gaps between the newspaper.  Those gaps will store the warm heat in the air pockets, which will make the oven warmer. 

Step 5: Reflectors

By now, the oven sould be almost be complete.

The next step is to make the reflectors.  One person said that unless you live near the equator, you must need these, or the solar oven wont work.  Hopefully, you kept the tops of the boxes that fold over the top to close the box.  You will then cover them with tinfoil.  It is best to be kept at a 45* angle, although if anyone has any thoughts on how to keep it up, please tell me.

Remember to use the shiny side of the tinfoil, and the see-through tape. 

Step 6: Glass

The last main step of my awesome solar oven is the glass part.  The more exact it is, the less hot air will escape, which will let your food product to cook faster and better. 

I used a big picture frame, and cut it down to its apropiate shape (My dad helped me with the sharp parts). 

I am not going to tell you how to cut glass, so that will be part of your job to figure out how to cut it.  It will probably tell you on the glass cutter, though.

Step 7: Clean and Protect

After you carefully cut the glass to your desired dimensions, you must make sure it is safe.

The way I did this was I put Super Duty Duct Tape on all the edges.  I also put two layers on the corners there are no injury's.

After, I used glass cleaner on both sides to clean it so it is shiny.  I recomend not spraying the cleaner near the tape; just incase the tape gets soggy and comes off.

Step 8: Rack's

Before you place the glass on your oven, you might want to do this...

An optional idea is that you can place a baking rack on the bottom of the oven.  It would be better if all the sides cooked (top, bottom, and inside).

Step 9: Thermometor

Another good idea is to use a thermometer.  Depending on the kind you own, you can just place it in the oven and check on after a while. 

My last suggestion to have a timer, and double the timing on your timer for a regular oven.

Step 10: Please Enjoy

I hope you can cook some very edible meals in my oven.  If you have an suggestions or ideas, PLEASE TELL ME!  I also want to hear what your findings were to.  If you have any questions, you can also ask me.

Ben G.

2 People Made This Project!


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62 Discussions

Where does the glass go? On top of the small or big box? I'm building a solar oven for my environmental science class and I'd like for it to work properly and bake the cookie.

Its really a wonderful project! You did a marvelous job building it too! I have collect some other diy solar cooker projects and prepared a round of 10 ideas. I have featured your project in my blog post :


1 year ago

A small tip. To remove the sharp edges of the glass use fine sandpaper.

Second prob: Can't boil water at 100 deg C then how can bake things at 180 or more???

1 reply

For your second problem, you're asking how things can bake at above 180°C if water boils at 100°C, right? Well... I mean, water boiling is not really a problem. It's not like all the water will instantly evaporate the moment the temperature hits 100°C, so it doesn't really matter.

If you want a nontoxic insulation,use cotton or wool batting.I like the idea of using a black cotton tee shirt like one person commented.I will be using an emergency Mylar blanket instead of tinfoil,they are great fro holding in heat

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!

4 replies

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.

Infrared radiation does carry energy, you're right, but it's not the only one. Actually all radiations carry energy: visible, infrared, ultraviolet, X-rays, etc. Visible light having a shorter wavelength than infrared, they carry more energy than the later. Regarding the properties of aluminum, it does reflect infrared light, almost as well as visible light (I have read about a reflection coefficient of 95% on the internet).

Anyway, the heat absorbed by the aluminum coating is not really of matter. The working principle of solar ovens is to reflect (concentrate) sun beams into one point, not to absorb heat and then conduct it. To come back to the original comment: I also believe painting the inside of the box in black is useless, and if it has en effect of the heat received in the focal of the parabola it will account for less than 1%.

If you paint it black it traps more heat in just fyi and I knew that

You paint the bottom black to absorb the heat, you don`t put the tin foil on the bottom just the four sides like it says!

Going to make this for my Science class!

What was the point of painting the bottom black if you were going to put tin foil over it. I donut understand

1 reply

You only cover the sides with aluminum foil, so the bottom stays black to absorb heat.

Trap's hot air. You need a good seal around the glass.

Does anyone know this model is safe to boil water in?

1 reply

Water won't boil in it, but after a few hours on a sunny day you can get it up to pasteurization temperature at least (165F).