Solar Cooker is a device that uses energy from sunlight for the purpose of cooking and heating. We generally use stove, gas oven or electricity for cooking, which are based on conventional sources of energy, but a solar cooker uses solar energy, which is a renewable form of energy. Read this article to learn all about Solar Cooker, its working procedure, and its application.

What is Solar Cooker?

Solar Cooker is a device that harnesses heat from solar energy and use it for cooking and heating. Unlike the gas stove and other cooking devices which use conventional and non-renewable forms of energy, solar cooker uses renewable and non pollution form of energy. It is a non-polluting and clean device that doesn’t cause any emission. It concentrate sunlight falling on it which causes the increase in temperature and thus helps in cooking. Although it slowly cooks the food but save the nutrition of the food. Because of its good properties, government of India provides subsidy on Solar Cooker to promote it.

Working Principle of Solar Cooker

Solar Cooker is working on the following principles:

Using Mirrors to Focus Sunlight or Concentrate Sunlight

A highly reflective concave mirror surface is used for cooking by using sunlight. The concave mirror concentrates and directs the sunlight into a small cooking area. This helps to increase the magnitude of the sunlight, which produces a high temperature, enough to cook. The solar cookers are designed to achieve temperatures ranging from 65°C to 400°C, which is enough for cooking.

Converting Light Energy to Heat

The concentrated sunlight is directed onto a receiver that is a cooking pot. The light energy transforms into heat by the interaction between the light and the material of the receiver. This process is known as conduction. The conversion can be maximized by improving the conducting materials and retain heat. To absorb maximum light , black painted pot is used in Solar Cooker.

Trapping Heat

Once we retain heat in Solar Cooker, we have to keep it inside as much as we can. For this , we have to minimize the effects of convection. By isolating the air inside the Solar cooker from the external air, we can reduce the effects of convection. By using a glass lid on the cooking pot we can reduce the loss of heat through convection along with enhances light absorption from the top of the solar cooker. The glass lid is used to hold heat inside the cooker and captures incoming sunlight.

Types of Solar Cooker

Solar Cookers are generally four types

• Panel Cooker
• Parabolic Cooker
• Evacuated Tube Cooker
• Box Cooker

Panel Cookers

Panel cookers are looking like an open and three sided box. Panel cooker is generally used for cooking of soups, meats, vegetables, casseroles, and desserts etc.

Box’s three side panels are covered with shiny material which acts as a reflector. The shiny panels are hitted by the sunlight and then reflected into the center of the box. For capturing the sun rays inside the box, a ‘heat trap’ is used. Heat traps are able to pass UV rays. Inside of the heat trap, cooking pots are placed. When the UV rays hit the cooking pot, the molecules of the cooking pot begin vibrating. During vibrating, light ray transforms into heat. Through this process, The generated Temperatures ranges from 121° C to 149°C.

Parabolic Solar Cookers

Parabolic solar cookers look like parabolic satellite dishes. Parabolic Solar Cooker is generally used for frying and grilling.

A reflective shiny material surface fully covered the dish. When the dish is hitted by sunlight, it reflects the sunlight to the center focal point. At the focal point of the reflective surface, a cooking vessel is placed . The high temperatures range from 500°F ( 260°C) to 700°F (371°C).

Evacuated Tube Cookers

Evacuated Tube Cooker is newly launched and less popular device.

Evacuated Tube Cooker is made from a large evacuated glass tube which is surrounded by shiny reflector panels. In this glass tube, the temperatures are from 550°F (290°C) or greater. Evacuated Tube Cooker is used to cook meat, bread, vegetables, and dessert.

Box Type Solar Cooker

Box type solar cooker is commonly used in the form of solar cooker. Box type solar cooker contains mainly four components – Black box, Glass sheet, Mirror and a cooking pot.

Black box: The black box is a type of metal box or wooden box. It is insulated type box. To absorb maximum heat, it’s inside portion is painted by black colour.

Glass Sheet: Glass Sheet is made of toughened glass. It allows the reflected light into the box.

Mirror: The highly reflective mirror is used in box type solar cooker. The mirror is fixed in an angle from which the maximum sunlight reflected on the glass sheet of the box.

Cooking pot: Cooking pots are the containers that are used for cooking. It is made by aluminium that is blackened externally.

Making of Solar Cooker

Although solar cooker is abundantly available in market but is a bit costlier than conventional stoves. Hence, we can make them at our home. Students can also use them for science project ideas. The making solar cooker is discussed below:

Required Materials

To make a box type solar cooker, the following materials are required –

• A wooden box or a material box
• Aluminum sheet (Highly Reflective)
• Black paint to paint the black box and cooking pot
• Mirror
• Glass sheet
• Hinges
• Wooden lid for the box and 
• Cooking pot or Container.

Making Procedure

• Take an insulating Wooden box.
• An aluminum sheet which is painted black is placed inside the wooden box.
• A concave mirror is placed on the top side of the wooden box with an angle, so that maximum sun rays are received by the mirror and then it reflects the sunrays into the box.
• The open side of the wooden box is covered with toughened glass sheet. Glass sheet takes the reflected sunrays from mirror and placed it inside the box.
• Inside the box, cooking pots are placed. The cooking pots are painted black externally.

Application of Solar Cooker

Applications of Solar Cooker are as follows –

• Solar cooker is used to Roasting coffee beans , popcorns and peanuts for commercial purposes.
• Water Distillation is done by Parabolic Solar Cooker. Water distillation is done by boiling the water constantly.
• Many industries can achieve more than 2400°C from solar cooker which melts iron very easily.
• Separation of Beeswax and melting the capping
• Melting of Wax is done by solar cooker.
• Sterilization of Medical apparatus such as needles, gauge bandages.
• It is also used for Ironing. Even it is not a conventional way on ironing. Iron is heated by parabolic solar cooker and then it is used for ironing cloths.
• Purification of Water . Solar cooker is used for water purification by heating water.
• Solar cooker is used for Dehydrating foods. The lid of the cooking pot is partially opened , so that it prevents from the excess heating.

Advantages of Solar Cooker

Solar Cooker is used in household purposes as well as commercial purposes. The followings are the advantages of Solar Cooker –

• Solar Cooker keeps environment pollution free. It doesn’t affect on environment.
• Fuel is not required for cooking in Solar Cooker.
• The food that is cooked in Solar Cooker, contains high nutrition value.
• Solar Cooker is available in various sizes. So that a family can buy solar cooker according to the number of their family members.
• Solar Cooker is a government scheme, so a reasonable subsidy will be provided to the buyers.

Disadvantages of Solar Cooker

Solar Cooker has a few limitations or disadvantages. These are given below –

• Solar Cooker takes too much time to cook any food.
• Solar Cooker is working only in the presence of sunlight. At night Solar Cooker is not working.
• In cloudy weather, it is very hard to cook food by using solar cooker.
• During strong winds, solar cooker’s working process is less effective

Solar Induction Cooker

Solar Induction Cooker is a type of solar cooker which uses the sunlight as the source of energy. Solar induction cooker is based on the mainly two principles. These two stages are –

• Dc to Dc converter stage
• Conversion of boosted Dc to high frequency Ac

Due to the very less output from the solar panel, DC to Dc converter is acts for boosting action. To get high frequency requirement(20KHz-100KHz) in induction cooking, Dc to high frequency Ac conversion stage is must be needed.