Solar oven

Solar oven, also called solar cooker, a device that harnesses sunlight as a source of heat for cooking foodstuffs. The solar oven is a simple, portable, economical, and efficient tool

Especially in the developing world, solar ovens are much to be preferred over other methods of cooking. Of the many advantages of solar ovens, the greatest is its freedom from the necessity for fuel. Solar ovens thus not only remove any persistent labour or monetary costs associated with cooking, but by conserving often scant resources in the long run they prevent deforestation and desertification. Solar ovens are also useful in the developed world whenever electricity is unavailable and traditional open fires are undesirable, such as while camping.

Types Of Solar Ovens

Solar ovens are available in many designs that employ an array of different materials and approaches. Each design must be capable of concentrating sunlight from over a wide area to a central point. At that central point, a black-surfaced vessel helps convert the sunlight into heat, which is used to cook the food. Further, once the heat is generated, it must be trapped and insulated from the cooler air outside the cooker. The basic designs are as follows:

A box cooker consists of a number of mirrored panels that focus their beams toward an insulated box structure, which has a transparent top used to admit the solar radiation. Black-painted cooking pots and pans are placed inside the box.
A hybrid cooker is a box cooker equipped with a supplementary electrical heating system, which can be used at night and when it is overcast or cloudy. Those tend to be larger, fixed installations for use by a community or group.
Parabolic cookers—which use a parabolic mirror to focus the sunlight to a central point at which the cooking container is placed—are capable of generating high temperatures, but they are more difficult than the box cooker to construct.
Panel cookers are the least-expensive type of solar cooker. The panels, often made of corrugated cardboard and covered with an inexpensive reflector such as aluminum foil or Mylar, focus the Sun’s rays onto a black cooking pot, which is kept inside an insulating plastic bag.

Cooking With A Solar Cooker

Solar cooking requires a slightly different approach to food preparation. Because food cooks faster in smaller pieces, those who use solar cookers often chop food into small pieces to decrease the amount of time required to complete the cooking. Further, the device is turned to face the Sun and may require regular realignment to ensure that it receives the optimum solar gain. Finally, food prepared in a solar cooker generally is not stirred or agitated, in part because that activity slows the cooking process and in part because a lifted lid allows heat to escape.

Solar Ovens: Food Fueled by the Sun

Solar energy isn’t limited to home lighting anymore. Today, the sun can power nearly any device that would otherwise consume electricity, from phone chargers to refrigerators and even air conditioning units. But one solar appliance in particular can reduce power plant pollution and contribute to communities around the world – all while serving up snacks.

Enter, the solar oven.

As its name suggests, the solar oven harnesses sunlight to sustainably cook food and boil water. If you’re living life “off the grid,” solar ovens offer significant energy savings, without sacrifice … as long as you aren’t opposed to an outdoor kitchen.

However, the impact of the solar oven transcends this niche market of eco-conscious consumers. In rural countries where electricity isn’t easily accessible, solar cooking provides a practical and healthy alternative to burning organic compounds that release toxic smoke.

How does a solar oven work?

Instead of converting solar energy to electricity, solar ovens trap light particles, called photons, to generate heat. With the help of metal reflectors, which are positioned around the oven to maximize light input, photons pass through the oven’s transparent glass top and strike the interior of the insulated box.

For best results, a dark, metal pot is placed at the center of the oven, where it can absorb the incoming photons. Once the cooking pot becomes warmer than the surrounding air, the heat attempts to escape to a cooler space. However, since it cannot break through the glass barrier, it remains trapped inside. As heat is reflected back to the metal pot, the oven’s temperature rises rapidly – up to a scorching 400 degrees Fahrenheit.

If you’ve ever left your car outside for a few hours on a sunny summer day, you’re already familiar with this phenomenon, formally known as the greenhouse effect. Sunlight enters your vehicle through the windows, heating up the seats and, before long, the entire interior.

Solar ovens operate in the same way, but these compact insulators allow you to cook in a proper pan instead of on your car’s dash.

A bright future for solar power

Although it may not be realistic to swap your high-octane electric oven for a solar cooker, you can reduce your home’s environmental impact with these simple energy saving adjustments.

As we discover new applications for solar power, we look forward to a future where this eco-friendly fuel source improves the state of the planet and the quality of our lives.

Solar Oven Facts

Every time a clock’s second hand ticks, the sun converts four million tons of mass into energy. Because it’s millions of miles away, the sun won’t vaporize the planet, but it can help you bake a tasty pizza. You won’t obtain high enough temperatures to do that by leaving food in the sunlight — even on the hottest day — unless you use a solar oven and let the harnessed power of a trillion megaton bombs cook meals for you.

Solar Energy Meals: Pros and Cons

It may take longer for a solar oven to make your favorite dish, but the benefits may offset that inconvenience. If you like to save money, rejoice because you won’t need to spend it on fuel for a solar oven. No fuel means no open flames that can cause fires. Food rarely burns because it cooks slowly, and your workload is minimal since you usually don’t need to stir anything. Finally, a solar oven’s portability makes it easy to transport.

Additional Global Benefits

A solar oven’s benefits may vary depending on where it is used. In less-developed countries, these ovens eliminate the need for women and children to spend time gathering fuel for cooking. In forested areas, the ovens help slow deforestation by eliminating the need to harvest wood for fuel. A solar oven’s portability becomes even more important when it can help people prepare meals when they’re isolated from power and fuel. Solar ovens also help protect the planet’s environment since the don’t use fossil fuel.

The Cooking Power of Focused, Trapped Energy

Several types of solar oven exist, but they all work by focusing the sun’s energy onto your meals. Panel ovens, which usually have multiple panels, reflect light onto food. Parabolic ovens — usually the best cookers — focus light as well, but that light arrives at a single focal point where heating occurs. If you get one of these ovens, place food at that focal point for best results. Box ovens function like greenhouses, trapping infrared radiation inside the container after light waves enter through an opening. You can cover that opening with clear plastic, but glass traps heat better.

Maximize Your Solar Cooking Experience

A solar oven functions more efficiently if you remember a few important tips. Ensure that the cooking container is dark and its reflective material is smooth; dark colors absorb more energy than light ones. It also helps to position your solar oven so that it directly faces the sun. Seal a solar oven tightly and insulate it well to keep heat from leaving the container. If you cook dishes that contain liquid, seal them inside the oven; this prevents heated water from condensing and covering the container.

How Solar Cooking Works

Using stoves and ovens, we can cook foods like meat, vegetables, beans, rice, bread and fruit in just about any way. We can bake, stew, steam, fry and braise. Using a solar cooker, we can do the same things, but by using sunlight instead of gas or electricity.

Sunlight isn’t hot in and of itself. It’s just radiation, or light waves — basically energy generated by fluctuating electric and magnetic fields. It feels warm on your skin, but that’s because of what happens when those light waves hit the molecules in your skin. This interaction is similar to the concept that makes one form of solar cooker, the box cooker, generate high temperatures from sunlight.

At its simplest, the sunlight-to-heat conversion occurs when photons (particles of light) moving around within light waves interact with molecules moving around in a substance. The electromagnetic rays emitted by the sun have a lot of energy in them. When they strike matter, whether solid or liquid, all of this energy causes the molecules in that matter to vibrate. They get excited and start jumping around. This activity generates heat. Solar cookers use a couple of different methods to harness this heat.

The box cooker is a simple type of solar cooker. At maybe 3 to 5 feet (1 to 1.5 meters) across, it’s essentially a sun-powered oven — an enclosed box that heats up and seals in that heat. At its most basic, the box cooker consists of an open-topped box that’s black on the inside, and a piece of glass or transparent plastic that sits on top. It often also has several reflectors (flat, metallic or mirrored surfaces) positioned outside the box to collect and direct additional sunlight onto the glass.

To cook, you leave this box in the sun with a pot of food inside, the pot sitting on top of the black bottom of the box. When sunlight enters the box through the glass top, the light waves strike the bottom, making it scorching hot. Dark colors are better at absorbing heat, that’s why the inside is black. The molecules that make up the box get excited and generate more heat. The box traps the heat, and the oven gets hotter and hotter. The effect is the same as what goes on in a standard oven: The food cooks.

Box cookers can reach up to 300 degrees F (150 degrees C) . That’s hot enough to safely cook meat.

A parabolic cooker can get even hotter, up to 400 degrees F (204 degrees C), which is hot enough to fry food or bake bread. This slightly more complicated design uses curved, reflective surfaces to focus lots of sunlight into a small area. It works a lot like a stove, and it’s big, sometimes up to several feet across.

A pot of food sits on an arm that holds it in the center of the curved reflectors, suspended slightly above the bottom point of the oven, where all the light is concentrated. This small point gets so hot — and the molecules vibrate so much — that the heat waves move upward in a steady stream to strike the bottom of the pot.

Both parabolic and box cookers are quite large, making them difficult to carry around. And box cookers are heavy because of the glass. A panel cooker, which uses parabolic reflectors positioned above a box-type oven, tends to be smaller and lighter. The cooking pot goes in a plastic bag while it cooks, which acts as a heat trap (like the transparent top on a box cooker). People sometimes use these types of cookers in camping.

Camping is something of a side job for solar cookers, though. The more central applications have to do poverty, hunger and disease.