Introduction: How to Make a Simple Cardboard Solar Oven

Picture of How to Make a Simple Cardboard Solar Oven

The sun is arguably one of the humanity's most important tool for survival. It gives off practically unlimited amounts of light that is used by plants to generate energy and animals for heat. It can be used to generate electricity with solar panels, hot water with solar hot water heaters, and many other uses. Even though technology can be very useful, for example gas ovens, natural and simple technologies like solar ovens can reduce fossil fuel use or even replace fossil fuels in places that don't have abundant resources, and it's an enjoyable project. The materials used can mostly be found locally from recycled sources which makes it even more sustainable.

Step 1: Finding Tools and Materials

I recommend taking one trip to locate/buy tools and materials for this job. The following materials are necessary:

-2 medium to large cardboard boxes that fit inside each other with 3-4 inches or so of space around the sides of the box.  Also necessary is a large piece of cardboard for the reflector that is as wide as the widest part of the large box and about 2-3 feet long. These can be found at most stores, just ask an employee for boxes they don't need anymore.
-1 roll of aluminum foil (75 feet is enough)
-a piece of glass or plastic fits over top of the larger box. This can be found at window stores; they often have extra glass laying around for free.
-tape measurer
-razor knife
-school glue
-black spray paint or black construction paper
-enough newspaper that will, crumpled, fill a bottom row and the sides in between the two boxes. This can be found at recycling centers.
-duct or foil tape
-two small pieces of wood (optional)

Step 2: Cutting Off Flaps of Smaller Box

Picture of Cutting Off Flaps of Smaller Box

Cut off the four flaps of the smaller box so they don't get in the way.

Step 3: Crumpled Paper on the Bottom

Picture of Crumpled Paper on the Bottom

Crumple up pieces of newspaper one at a time until the bottom of the large box is lined. This will be an insulation that keeps retains heat in the box.

Step 4: Spraypaint the Small Box Black

Picture of Spraypaint the Small Box Black

Either spraypaint the inside bottom of the small box black or glue a sheet of black construction paper. fitted to the size of the box, to the inside bottom of the small box. I recommend doing this outside and try to not inhale the fumes.

Step 5: Glue Aluminum Foil on Insides of Small Box

Picture of Glue Aluminum Foil on Insides of Small Box

Squeeze a generous amount of glue on one side of the inside of the small box and then cover it with aluminum foil with a little bit extra over the top of the box so it the foil stays in place. Then do the same for the remaining three sides.

Step 6: Insulating the Sides

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Crumple up one piece of newspaper at a time and fit it around the sides up to the top.

Step 7: Cut the Flap for the Reflector

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Cut a piece of cardboard that is as wide as the widest part of the large box and about 2-3 feet long.

Step 8: Installing the Reflector Flap

Picture of Installing the Reflector Flap

Put the cut piece of cardboard a few inches down on one side of the box and then tape it to a flap of the large box. (Optional: you can cut two small holes in the piece of cardboard and flap of large box once they are together and put two small pieces of wood in place two help hold the cardboard pieces together.)

Step 9: Putting Aluminum Foil on Reflector Flap

Picture of Putting Aluminum Foil on Reflector Flap

Apply a generous amount of school glue on one side of the reflector flap and cut aluminum foil to cover the entire side of the flap.

Step 10: Place Glass or Plastic on Top of Large Box

Picture of Place Glass or Plastic on Top of Large Box

Lastly, place the piece of glass or plastic on top of the large box and tilt the reflector in towards the center of the boxes. To cook something, find out how hot your new solar oven gets by putting solar oven in an open place with as few obstacles around to reduce shadows, and then face the reflector towards the sun. Then, place a thermometer inside and check it occasionally to determine how hot your solar oven gets. Feel free to experiment with different methods of cooking things, or look online for guides on how to cook using your solar oven. Thanks for reducing your fossil fuel use, cooking a more natural way, and I hope you make some scrumptious meals!


fastermx (author)2015-03-13

I want to ask if anyone here can give me some good pointers about making a solar oven with cardboard boxes. You know, tips on what to do and what NOT to do, stuff like that. I'd like to know how long it would take to cook about 2 lb of dry beans in water to the point where they're very tender.

I live in Mexico, in a working-class neighborhood. I told them about ovens like this several years ago, but I guess they didn't really believe it would work. Mexico, however, is a perfect place to use these ovens, since most days are sunny.

Lately, though, the price of gas is over 400 pesos, so now I think they may sit up and listen, especially if I can make one and SHOW it to them.

Most Mexicans eat a lot of beans, even if they're well-off. Beans aren't terribly expensive, but the hours on the stove now makes them costly to cook. They usually take 4-6 hours on the stove.

I guess you could say I'm trying a project that I hope will become a fad here. It will help many people struggling to make ends meet.

Any tips or ideas?

Sharrygranny (author)fastermx2017-10-13

First of all, lets talk about cooking beans. Try to get beans picked in the current year, they cook quicker.

Second, beans should not EVER need to be cooked this long. Rinse the beans, pick out the funny stuff--and soak them in lots of water over night. Dump water off, and the next day, if they are fresh, they will cook in in lots of fresh water in less than 2 hours. Then you can add them to sauces or 'bake" them, but boiling them in water, with a few onions, maybe some bacon or ham or ? and salt, is the proper cooking method and can be done on a "Rocket Stove" with a few twigs and small sticks, or try them in the solar oven in a black pot. After the beans are cooked, add seasonings, and bake them in your solar oven. Trying to make baked beans with dry beans ? I don't know how long that would take and how much liquid, but forever' would be a guess.

GarethP (author)fastermx2016-03-18

Hi change-agent, el Mexicano,

This idea of urs seems great. Dont worry about the opinions other others, as u say that will change when the standard petro/fossil feuls dont stack up.

Just get going and start experimenting with local recycled or plexi glass may be difficult.

Organise a small feast day and invite positive friends and influencers in ur community.

Maybe have a few starter kits ready to go as door prizes...prendi?

Contact the local scout group and demonstrate to through the back door to the parents.

Contact local social welfare agencies who may want see a demo to lhelp out less privileged , even homeless should able to use it. Let me know how u go?

regardes gareth, Noosa Heads<Australia

Dylanvan69 (author)2016-10-06

It smells like Mexico

Mlcanale (author)2010-09-27

I have a fear of the cold and would like to go camping. How can I make a solar heater for a small tent?


Dylanvan69 (author)Mlcanale2016-10-06

have you ever looked it up?

oakleaf1 (author)Mlcanale2011-01-06

Try this concept from THE MOTHER EARTH NEWS. You'll have to figure out the modification to adapt to a tent, but the design should work.

thomdickey (author)2015-12-10

I am really glad I found this & it is so very simple that even a person like myself can put one of these together. It is certainly going into my book that I am compiling for DIY Survival. Not that I am going to publish it since it is going to be mostly other people's work but for me, friends, & family. Thank you

amy.l.marks.9 (author)2015-02-04

Many years ago (may more than a decade?) we made something like this in Girl Scouts. To simplify we had used a oven turkey roasting bag instead of glass or plastic, you can cut some of the sides of the bag to make it a large single thickness. It can stand heat. It was easier (and cheaper because of the little bit of money we had from dues). I think the temperature may have been lowered. But in a situation where you may have to improvise, the idea is there. We did slowly cook some small meat loaf bites that were stuffed in the bottom of muffin pans. We had put it on a metal mesh cookie cooling rack to circulate heat.

Shelbert123 made it! (author)2014-11-17

I made this with a few minor changes to heat water. I spray painted the inside of both boxes black and used tin foil over the black paint. I also made my top flap out of the lid of a paper box and kept the overhang at the top to help the sunlight reflect down. From there I covered two 20oz bottles of water in foil and placed them inside the smaller box. Overall it was pretty effective as a solar hot water heater. I'll be sure to cite you in my lab report. ^_^

Giesterfarher (author)2014-10-11

My sister is a school teacher, and has her students make these from time to time. I've looked at a few of the examples her husband has made at home, and he likes to use fiberglass insulation wrapped in aluminum foil for the insulation between the inner and outer boxes.

On a 85 degree day in spring, my digital thermometer showed 540 degrees in less than 4 minutes using a glass top and glass mirrors inside, with aluminum foil reflector flaps. With the flaps folded down out of the sunlight, the temp is a much more manageable 310 degrees.

jaytea1973 (author)2014-08-15

We made one of these about 20 years ago while camping and it was amazing how well it worked. The whole chicken that we cooked was the juiciest and best tasting ever. It does take a long time, but it can be cooked within a day. The instructions were a little different and they came out of a library book (this was before we had a computer and the Internet), but I'm sure the results come out the same.

baoq12 (author)2014-04-17

Hi you. I did try solar cooker like you but not effective as expected. I've tried boiled eggs in 2 hours but still not ripe eggs. You know why not? Thanks

diy_bloke (author)2013-09-18

I heard once it increases efficacy if you actually place the pan in a plastic bag in the oven and put it on a spacer, like say a pan rack

joshem (author)2013-09-16

Very beautiful!!!!!!

Andy Andikko (author)2013-06-15

This is the easiest method thanks

cricket fan devu (author)2013-05-27

hi this is devang agnihotri from INDIA the design is very good and the best way to save L.P.G IN COUNTRY LIKE MY INDIA

lbrouse (author)2012-01-28

I have taught school (7th grade, high school technology, chemistry and physics, plus college-level chemistry and instrumental analys) for 13 years. My high schoolers have built models of various passive solar houses. The models that had no thermal mass inside rapidly increased their temperature to over 140 degrees. Several models that had collector flaps with aluminum foil coating that focused 4 square feet of input area into a 4 square inch collection area lined with black paper, reached over 450 degrees F within less than 1 minute. Models that had thermal mass (water inside black painted soda pop cans) increased the interior temperature more slowly but collected and stored more total heat. The high specific heat of water allows the heat to be stored without incrasing the water temperature very many degrees. I suggest experimenting with as many combinations of collection, insulation, and thermal storage as you can. You will begin to get a FEEL for the way these systems work and which variables will give you the characteristics you desire.

solaroven (author)lbrouse2013-02-18

Thanks for the suggestions. I will experiment with more insulation and thermal mass, e.g. soda cans or other metal cans with black paint. It would be more efficient if the heat were stored within the oven, as storing heat can create higher temperatures.

plancton man (author)2012-01-21

Hi Solaroven,

Are you worried about the presence of paint and glue chemicals in a food-processing device?

solaroven (author)plancton man2012-01-24

I don't know if the heat would be enough to cause chemicals to be released from the spraypaint, but it may be better to not use spraypaint or use non-toxic black spraypaint. Or you could tape black paper on the inside walls of the box. but the Elmer's glue should be fine since it's non-toxic.

uglymike (author)solaroven2012-04-12

You can use High-Temp grill spray paint. It's designed to be used in high tempratures and won't leech off toxic chemicals.

MOSLAW (author)2012-02-15

can i boil water with this

charlis1 (author)2011-04-11

Instead of cutting the flaps off, how about just flattening them to the outside walls of the box? They would add some insulation, then I would try using as many sheets of cardboard as would fit in the spaces instead of the crushed paper. All the corrugated and solid layers would add great insulation, I would think, as well as making the whole box stronger. I'll make one that way and report back.

johnny3h (author)charlis12011-09-04

I agree with you charlis1.  If well fitted cardboard sheets were used to fill the space between the two boxes, I think the insulating value would be greater than wadded newspaper.

However, IF the wadded newspaper prevents the outer box from heating above ambient, then our cardboard idea would be overkill.

Additionally, to use our idea of all cardboard for the insulation, several more boxes would be required.  I also agree however, that the full cardboard would add excellent rigidity to the assembly.

diy_bloke (author)2011-08-04

I really wonder if there is much use in painting the bottom black. Sure, black absorbs heat, but I doubt if that piece of corrugated cardboard is enough of a heatsink. Might as well do the opposite and glue alu foil to it.

Ofcourse cooking in a black pan in this contraption would be a good use of black

compaqxp123 (author)2011-07-05

I built this today. I'll try cooking something simple tomorrow afternoon.

I love the idea of being able to make a simple lunch in one of these rather then using electricity and having the stove warm up my house on these hot days.

mistdemon123 (author)2010-05-25

 how hot can the internal temperature get?

solaroven (author)mistdemon1232011-01-09

I haven't tested the internal temperature yet, there hasn't been much sun lately.

solaroven (author)mistdemon1232010-05-29

Hi there,
I made it for a school project and haven't used it yet, but when I do I'll message you. 

Thanks for your interest.

profpat (author)2010-09-25

great simplicity idea!

Wasagi (author)2010-07-20


MaXoR (author)2010-06-02

LOL... whoever that is doing the paper crumpling..... you look like me! (Who's!)

Just found that funny..... if that is actually you culture..... then it's even more funny, because I've gotten a glimps of your opinions, views, and obviously you're an inventor, tinkerer, green enthusiest, and out of box thinker..... it's creepy how alike we are.... yet stumbled into meeting eachother.

solaroven (author)MaXoR2010-06-02

The person in the picture doing the paper crumpling is also (me) the writer.  Here it's definitely the culture, I'm in University right now studying sustainability.  Just wrote a paper about ants, how when there's a room of, say, 7 ants they don't get much work done, and actually stop moving. But when there are more ants, they bump into each other and then the ant moves again. So, just like ants, the Sustainability Revolution is about spreading knowledge to each other so we get the revolution going.  Good day and pleasure meeting you.

cocoisa (author)2010-04-26

Me encanto la idea de hacer el horno solar para los campamentos.
Voy a probar este lindo invento Muchas gracias.

Lee Wilkerson (author)2010-04-23

You can also gain more heat by adding angled wings to the sides of the reflector panel thus:  \_/.

fegundez1 (author)2010-04-12

did you try it? let us see the results and how long did it take etc, thanks for the idea though its the time of year that a lot of people can start using these to really save.

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