If you have a few cardboard boxes and you are interested in a science DIY then one of the ideas you can deploy is making a solar oven. All you need to make a solar cooker at home are materials easily found at home. However, before you learn how to make a model of solar cooker, let's first understand what is the solar cooker and how is it used.
A solar cooker gathers sunlight and creates heat to cook food without using other fuel sources. Solar energy is a clean and renewable source of energy which helps prevent fossil fuel usage, deforestation, and greenhouse gas emissions. Popular among environmentalists and, campers and rural areas, solar ovens are an affordable and sustainable cooking method.
Solar ovens collect sunlight and direct it to an enclosed surface, where this trapped heat helps cook the food. They require highly reflective materials (such as mirrors, aluminium foil or any polished metal) set at particular angles to gather light. Solar ovens need to retain the collected heat well which is done by separating outside air from the air inside the cooking vessel.
Materials required for solar cooker DIY
Cardboard pizza box
Box knife/cutter or scissors
Clear tape or cello tap
Plastic wrap (you can also use a freezer zip lock bag)
Black construction paper
Ruler or wooden spoon
You may require the help of an adult to help you with the cutting work.
Step 1: Use a box cutter or sharp scissors to cut a flap in the lid of the pizza box. Cut along three sides of the lid only, leaving about an inch between the sides of the flap and the edges of the box. Now, fold this flap so that it stays upright when the box lid is closed.
Step 2: Cover the inner side of this flap with aluminium foil to make it reflect the rays from the sun. You need to wrap the foil tightly around the flap and tape it to the back or the outer side of the flap.
Step 3: Use clear plastic wrap to create an airtight window for your solar oven which would help the sunlight enter the box. To do this, you need to open the box and tape a double layer of plastic wrap over the opening made by cutting the flap in the lid. You need to leave about an inch of plastic overlap around the sides and tape it securely down each side down. The purpose of doing this is to seal out the air. If you do not have plastic wrap, you can also use a plastic bag. Cut out a square big enough in the plastic bag to cover the opening made in the lid and tape one layer over the opening.
Step 3: Line the bottom of the pizza box with black construction paper. We use black paper as this colour absorbs heat. The food will be cooked on this black surface only. The amount of black construction paper you require will depend on the size of the pizza box you're using to make your solar cooking stove.
Step 4: Next, you need to insulate your oven so that it retains more heat. To do this, roll up sheets of old newspaper and tape them so that they don't keep opening up. Now place them on the bottom of the box. Tape these rolls down so that they form a border around the cooking area on the black surface. The newspaper rolls should be placed in such a way that the lid of the oven can still close, but there is a seal inside of the box to trap the hot air.
The best time to set up your solar oven is from 11 am to 3 pm when the sun is high overhead. Place your oven outside on a sunny spot and adjust the flap in the lid in a way to get the maximum sunlight possible to reflect off the aluminium foil and onto the plastic-covered window. You can take the help of a ruler to prop the flap at the right angle or angle the box itself using a rolled-up towel. Place the thermometer inside your oven before closing it, so you can keep checking the temperature.
There are so many delicious recipes you can try making in your solar oven. You can make buttered toast by putting on a slice of bread in your oven. How about a juicy hot dog, or nachos with melted cheese? You simply need to put these treats in the solar oven and the sun will do the job for you. The solar cooker doesn't just cook food but it can also be used to heat up leftovers. To take your food out of the oven, simply open up the lid of the pizza box, and lift the glass plate using oven mitts or potholders.
Sun’s rays come to the earth at an angle and the foil in the oven reflects these rays, bouncing them directly into the opening of the box. Once the rays have passed through the plastic wrap, they heat up the air trapped inside the box. The black paper starts absorbing the heat at the bottom of the oven, while the newspaper rolls ensure that heat is retained and does not escape from the sides of the oven.
The solar oven can reach about 200° F on a sunny day and will take longer to heat things than a conventional oven. But it is very easy to make and use, and also to leave alone while the food is being cooked.
Once you’ve completed your solar cooker DIY and it is cooking delicious food, you must ensure to take care of its maintenance. If you don’t want the paper at the bottom of the oven to get dirty, you should use a clear plastic or glass plate (or a pie plate) to put what you would like to cook.