Mention solar energy and we think about panels on our roof generating electricity or hot water. But have you ever thought about cooking with the heat of the sun’s rays? For many people in developing countries solar cookers are a cheap and practical alternative to cooking with other fuels.
More than half of the world’s population rely on dung, wood, crop waste or coal for fuel. And about one third of the world’ population suffers wood fuel shortages. Developing countries often lack fuel but have abundant sunshine, so solar cookers make perfect sense.
With a bit of practice, you can cook anything in a solar oven can that can be cooked in a conventional oven – you can bake bread, roast meat and steam vegetables.
Types of solar cooker and how they work
Their advantages are many; as sunlight is the fuel, solar cookers don’t produce smoke (like firewood does); the fuel is free; they’re relatively safe compared to gas or electric ovens, as they don’t get hot on the outside. And they’re not fire hazards – if you kick it over there’s no fuel to spill.
Of course, an oven reliant on sunlight does have disadvantages. They’re most efficient during the hottest part of the day, and food takes longer to cook than in a conventional oven.
There are three main types of design, with myriad variations on each theme.
Solar Box Cooker
Box cookers cook at moderate to high temperatures, up to 150°C (300°F) and are large enough to hold more than one pot. As the name suggests they’re essentially an insulated box with a glass or clear plastic lid that concentrates and holds heat. Worldwide, they are the most widespread, with several hundred thousand in India alone.
Parabolic (concentrator) cookers cook fast at high temperatures, and perform like a conventional oven. They’re shaped like an umbrella, and focus the heat on to the cooking pot. But they are harder to build than box or panel types and need to be turned to track the sun’s passage through the sky. Several hundred thousand exist, mainly in China.
Panel cookers incorporate elements of box and curved concentrator cookers. They use reflective panels – e.g. aluminium foil-backed cardboard – to focus sunlight onto a cooking pot that is enclosed in a clear plastic bag. To use a panel cooker, it is folded into a bowl shape. The pot is placed in a clear plastic bag and the cooker is placed in direct sunlight until the food is cooked. For faster cooking, the pot can be raised on sticks or wires to allow the heated air to circulate underneath it.
Make solar cooker model for school project
There are over 100,000 solar cookers in both India and China, showing that simple tools like solar cookers really can be effective and reliable for cooking.