Learning how to make a DIY solar oven can be a fun and rewarding experience. Even though you most likely already have and use a traditional oven, this project is a fun – and tasty – experiment in solar power. This will make a great camping activity, or a safe and impressive science fair project.
Whether for fun, science, or an emergency, it’s a smart idea to understand the basics of cooking in a DIY solar oven. The process for building one is quite simple and the simplest version will take less than an hour to make, plus it’s very safe for kids to construct with minimal supervision. Cook safely, and for free, with your own homemade solar oven cooker.
How Does a Solar Oven Work?
A solar oven or solar cooker is a device that basically uses concentrated thermal energy from the sun, instead of gas or electricity, to heat and cook food outside (similar to a sun-powered grill). It can be a handy skill to know how to build and use a solar cooker. This is an excellent alternative or supplement for your backyard or beach barbeques. It’s also a near-invaluable skill to use on camping trips and other outdoor adventures and goes great with a solar-powered refrigerator.
The fundamental principle of a solar oven is its ability to utilize concentrated sunlight to generate heat. To successfully build a solar cooker of your own, you’ll need a surface (or series of surfaces) that are capable of directing the sun’s rays onto a small cooking area. The smaller and more compact the area, the better. You might think that temperatures from a solar cooker would not be enough to cook or bake, but this method is actually quite reliable and it’s been used in construction industries to melt salts and metals.
This is possible because of the second principle of a solar cooker, which is its ability to convert light into thermal energy. You can facilitate this by making sure that your cooking pot is as conducive to heat as possible. Matte black surfaces and cooking basins maximize light and heat absorption so choose these kinds of items if you can. Lastly, an efficient solar oven prevents heat from escaping. A lid (such as a glass lid) will often do the trick and even add a greenhouse effect to maximize your cooking temperature and time.
Learning how to make a DIY solar oven is quite simple. Below, you’ll find everything you need to know on how to build a solar oven and how to use it once it’s done. If you’re looking to do something similar but simpler, try one of these solar dehydrators.
Supplies for Making a Solar Oven
Solar ovens might not be as reliable as their conventional counterparts. Conventional ovens allow you to cook without the need for direct sunlight, and they offer more control in terms of temperature and technique. But, a good DIY solar oven can mean cooking in the backyard in a free and safe way. In emergency circumstances, it can also mean the difference between eating safely cooked food or not eating at all.
A solar oven project is fun and easy because it doesn’t require special materials or expensive supplies. Everything you need for a lightweight solar cooker is affordable and easily found around your home. And if you add something like a solar coffee machine, you’re golden.
Here’s what you’ll need:
2 Cardboard Boxes
One box should be roughly a square foot (give or take; size is not mandatory) and the other should be a bit smaller. Unused boxes that held small appliances or items like a toaster, coffee maker, a microwave, or shoes work well for this project. Look for boxes that are not badly damaged or soiled. Ideally, one box should fit inside the other with about an inch of space surrounding all sides, in between the two boxes.
You’ll be using this paper to insulate the interior box, so your shredded paper will be going into that one-inch gap between the two boxes. Shredded newspaper works well because the dark black inks help to maximize the heat. Make sure you have enough to generally fill the space between the boxes. If you don’t have newspaper, most any other shredded paper will work. In a pinch, even torn cloth will work (the darker, the better).
4 Additional Pieces of Cardboard
The closing flaps of a box work well for this. If your larger box already has 4 closing flaps attached to the top, use this. If it does not, any four flat pieces of cardboard, of relatively similar size to that of closing flaps, will work. You’ll be fashioning these into heat reflectors later in the project.
Black Construction Paper
Gather several pieces of black construction paper. You’ll be using these to create a powerful heat-absorption process in your solar cooker.
This can be aluminum foil, metallic car sunshades, aluminum-coated bubble wrap, or even Mylar food packaging.
This project will require some basic construction tools as well. Collect scissors, a ruler or straight edge, and collect a fastening agent such as metal document clips, staples, a hot glue gun, or duct tape.
Instructions for Making a Solar Oven
Making a DIY solar cooker is a simple-to-follow process, that takes relatively little time, and it’s very safe for kids, too. Once you have all your materials and tools gathered, lay them out on a comfortable work surface in front of you. Make sure your boxes and everything else is dusted off and ready to go. Then, follow these steps to construct your DIY solar oven:
Step 1: Construct the oven box
Place the smaller of the boxes inside the larger and leave roughly an inch of space on all sides, between the two boxes.
Step 2: Insulate the cooker
Fill the space between the two boxes with shredded newspaper. Stuff the space so that it’s relatively full. It should be comparable to stuffing a fragile package for protection during shipping.
Step 3: Increase heat absorption
Using black construction paper, cover the entire inner surface of the smaller box. Every inch of the inner surface should be covered with black.
Bonus Step 3.1 – This step is not mandatory
For extra heat absorption, you can slide a piece of black paper between the smaller box and the shredded newspaper on each of the four sides.
Step 4: Box flaps
If your larger box already has flaps attached, you can skip this step. Otherwise, attach your individual cardboard pieces to the four sides of your larger box. You’ll want them each attached in a way that gives you the most mobility control over the panel. These flaps will be used to help you direct and concentrate light from the sun so they should not hang down or droop below the top of the box. Instead, they should pop up and open at a slight angle that slopes inward toward the smaller box.
Pro Construction Tip
To create an effective slope using the separate panels, at the bottom of each individual panel, draw a straight line across the cardboard, about ½-inch up. Fold along each of those four lines, so that each panel now has a mini-flap. Place one cardboard panel so that the crux of the mini flap sits atop the edge of your large box. The mini flap will be on the inside wall of the large box. Secure the mini flap against the inner wall with duct tape or whichever fastening method you prefer. Repeat this with the other 3 panels.
Step 5: Create reflective panels
Using your aluminum foil or other reflective materials, completely cover each flap. The entire surface of each flap should be covered, right up to the top of the large box. Try to keep these surfaces as smooth as possible for the best reflection capacity.
Great work! You’ve built a DIY solar oven!
Now all you need to do is find a sunny spot outside to test your cooker power. But, what if you want to use a DIY solar cooker that’s a bit more durable and longer-lasting? A more durable solar cooker can cook at higher temperatures, too. If you want to try a heavy-duty DIY oven, try this next set of instructions:
Build a Heavy-Duty Version
If you want to add a heavy-duty solar oven to your kitchen appliances for long-term use, then you’ll need a few alternative materials. The idea is generally the same, but you’ll be using more durable, and longer-lasting, industrial items to construct your oven. This method is a step up in terms of ease and safety. Children will require more help and supervision if you plan to try this DIY method. Because this method requires several pre-cut, fitted, parts, if it’s at all possible to have these items pre-cut at a home maintenance store, it will save you the trouble of cutting the items yourself.
Here’s what you’ll need:
A large steel drum, or metal drum bucket
Most commonly used is an old steel oil drum. You’ll be cutting this drum in half the long way with an angle-grinder, cutting torch, or similar tool. You’ll be retaining only one of the two halves for this project.
Sheet metal and pop rivets
You’ll need sheet metal which you’ll be measuring and cutting down to fit and cover the entire inside of your drum half. You can use the same tool for cutting this sheet metal as you used for cutting your drum. The pop rivets will be used to secure the sheet metal to the inside of the steel drum, so make sure to get 6-12 rivets to make sure you have enough.
Custom-fit tempered glass
Tempered glass will be used on the inside of the drum to create a clean and stable cooking surface. This glass, however, will need to be measured and cut to fit the inside of your cooker just so. This glass can be cut with a glass cutter or similar glass-cutting tool.
Barbeque-rated insulation and reflective paint
At any typical home maintenance store, you’ll also find a sprayable insulation that’s safe to use around cooking and high-heat. You’ll want this insulation spray and additionally, a barbeque-rated reflective spray paint, which is also intended for cooking and high-temperature situations, so you know you’ll be safe from toxic fumes mixing with your food.
If you prefer to cut your own pre-fit materials, you’ll need an angle-grinder or a cutting torch for sizing and cutting your metal materials. Similarly, you’ll need a glass cutter, or a tool intended to cut glass safely. You’ll likely need a drill as well, so you can affix the pop rivets to the sheet metal and drum.
Instructions for a Heavy-Duty DIY Solar Oven
If you can measure and pre-cut all of your materials, this will save you time and trouble. Collect all of your materials and tools and lay them out on a comfortable work surface in front of you. Then, follow these steps to construct a heavy-duty, high-temp, solar oven:
Step 1: Cut a drum
Start by acquiring a large metal drum (an oil drum, for instance) and cutting it in half vertically, not horizontally. You’ll be using only one of the two concave halves you’ve cut. This is also a good time to drill a few holes in what will be the bottom part of the solar oven, for drips and drainage.
Step 2: Clean and measure the drum half
Thoroughly clean your drum half as best as possible. Then, measure the inside of the drum carefully. You’re taking measurements for the sheet metal you will affix to the inside of the drum.
Step 3: Cut and attach sheet metal
Cut matching surfaces of sheet metal to fit and cover the inside of the drum. Secure the sheet metal to the drum by drilling holes and using pop rivets.
Step 4: Coat the inside of the drum and sheet metal
Once the sheet metal is secured in position, coat the inside of the oven with barbecue-rated reflective paint. Using this paint, create a small metal lip on three of the four sides of the drum.
Step 5: Add tempered glass
Your cooking surface inside the drum will be your pre-cut, custom-sized, tempered glass. This should be carefully measured and cut ahead of time. Place the tempered glass on the lips you’ve created. This should be comparable to placing the glass shelf insets back into your refrigerator.
Step 6: Insulate the cooker
Spray insulation on the backside of the cooker. This will take the place of the shredded newspaper and black construction paper.
Step 7: Construct a base to hold the cooker
With the drum now fashioned into your solar oven, the last step will be to construct a base to place your cooker on for stability. Cinder blocks, bricks, aluminum, or wood will make a sturdy base.
Bonus Step 7.1 – This step is not mandatory
For additional functionality, you can add a heat-resistant magnetic thermometer to the side of your drum to monitor your temperature.
Good job! Though this version of a DIY solar oven takes a bit more preparation and industrial materials, but now you’ve built a heavy-duty, high-temp, solar powered cooker!
How To Cook Food in Your DIY Oven
Time and place are essential aspects of cooking with a solar oven. Ideally, you’ll want to position the cooker in full sunlight, away from any potential shadows, to ensure continuous heat throughout the cooking process. For best results, use jars or dark colored baking pans to contain the food. The direct sun will raise your cooking temperature, but you’ll also need to plan for extra cooking time, as a solar cooker is typically slower than a conventional oven. To cook something by noon, you’ll likely want to start the process no later than 10 a.m., whereas a meal to be served in the evening should be in the cooker by 1 or 2 p.m. Give yourself a couple of extra hours until you’re used to use and timing. If you plan to leave the food inside the oven for most of the day, then simply orient the oven to match the position of the sun at noon. You can cook almost anything with your solar cooker, that you’d otherwise prepare in a conventional oven, by keeping in mind the temperature and speed of cooking.
Cooking in Your DIY Solar Oven
Now that the hard work is done, you’re ready for the fun! With cooking in your solar oven, the possibilities are pretty much endless. Time to reward your hard work with a delicious, sun-cooked, treat. Enjoy solar-baked chocolate chip cookies or s’mores. Try solar nachos or pizza crackers. Try a casserole or whip up a delicious chili. Try a full meal of rice, fish, and corn on the cob. Who would have thought that the sun can be so delicious? Start with basic recipes such as solar whole wheat bread, and work your way up to a lasagna. You might even attempt a beautiful peach cobbler. Let your creativity play – and eat! If you need a suggestion, try these solar starter recipes.
Solar Muffin Pizza
Split one or more English muffins in half and on each half, apply 1-2 tablespoons of pizza sauce. Over the sauce, sprinkle a generous amount of your favorite shredded cheese options. Place pepperoni slices or other desired toppings over the cheese. Place your muffin pizzas on a baking sheet or similar item that will fit into your solar cooker. Position your cooker and reflective panels for optimal sunlight and relax. Your pizza will be ready shortly.
For this bread, you’ll need:
- 9 cups of whole wheat flour (but you can use rye, or regular flour, too)
- 2 tablespoons of yeast
- ½-cup of potato flakes
- 2 cups buttermilk (can be replaced with a smaller amount of olive oil)
- 4 cups warm water
- 1 tablespoon of salt
Mix everything together and split the mixture into roughly 5 separate loaves, depending on desired size, into baking tins or sheets. Keep in mind smaller units of bread will cook faster than one large unit. Once split, let each unit sit to rise for about 30 minutes (longer is okay). Then, pop your bread units in the solar oven. Maintain a temperature of around 370 degrees F and keep the bread in the cooker for about 40 minutes. Check on your breads once or twice to make sure everything is cooking smoothly, and make any necessary adjustments as needed.
Congratulations, Chef! Not only do you know how to build a solar cooker yourself, but you know how to cook food within it. Now practice your skills and show off for your friends and guests when they join you for a cookout. You can even try this on your next camping trip. You’ll be surprised how fast, fun, and easy the project can be. And no one would believe you cooked such delectable treats inside a couple of boxes with the sun!
This DIY solar oven project is a fun and meaningful lesson for kids and it would make an excellent project for a science fair. It’s very safe, utilizes basic, yet often overlooked, science. And, the results are appetizing. If you’re looking for more fun DIY projects, take a look at our guide to build a solar-powered clock.