Solar Cooker

We use a solar cooker for cooking the food by using the energy radiated by the Sun. Solar cooker works on the principle that sunlight warms the pot, which is used for cooking the food.

Now, this warming of the pot occurs by converting light energy to heat energy.

Concave mirrors are used in these types of cookers because these mirrors reflect sunlight into a single focal point.

Here, the mirror focuses sun rays onto a receiver such as a cooking pan.

A solar cooker lets the UV light rays in and then transforms them into longer infrared light rays that cannot escape.

Infrared radiations have the energy to make the water, fat, and protein molecules in food vibrate energetically and heat up.

The process by which the interaction between the light energy and the receiver material turns light to heat is called conduction.

We can maximize this transformation by using materials that can conduct and retain the heat.

Working Principle of Solar Cooker

1. Using Mirrors to Focus Sunlight:

To make cooking using sunlight more effective, a mirror with a highly reflective surface is employed. This mirror concentrates and directs the sun's light into a small cooking area. By doing this, we can greatly increase the intensity of the sunlight, reaching temperatures high enough to melt salt and metal. However, for everyday solar cooking needs at home, we don't need such extreme temperatures. The solar cookers available in the market are designed to achieve temperatures ranging from 65°C to 400°C.

2. Converting Light Energy to Heat:

After concentrating the sunlight, it's directed onto a receiver, like a cooking pan. Here, the interaction between the light and the material of the receiver transforms the light energy into heat through a process called conduction. To maximize this conversion, materials that conduct and retain heat well are used. The pots and pans in solar cookers should ideally be matte black in color to absorb as much light as possible.

3. Trapping Heat:

To make sure we retain as much heat as possible, we minimize the effects of convection by isolating the air inside the cooker from the external air. Placing a glass lid on the cooking pot enhances light absorption from the top and reduces the loss of heat through convection. The glazing material captures incoming sunlight but is opaque to infrared thermal rays, further improving the cooker's ability to hold heat.

Types of Solar Cooker

There are two types of solar cookers, that is:

1. Type 1 - Box Type - Heat Up

In this type of cooker, heat gets reflected by a reflector into a box, and then the heat gets trapped by the top glass like a greenhouse effect and heats the cooking utensils.

2. Parabolic Type - Converge Heat to a Single Point

In this type, the heat converges to a  point where the cooking utensils are kept; it gets heated up and cooks the food.

Other categories are:

a. Box cookers (often called box ovens)

b. Parabolic cookers

c. Tube cookers

Box Type Solar Cooker

The main components of box-type solar cookers are:

1. An insulating metal box painted black from the inside,

2. A glass sheet, and 

3. A reflector such as a plane mirror.

Let’s understand the working of the box-type cooker:

The box is covered by a transparent glass sheet which allows the infrared rays coming from the sun to enter the box.

The metallic box is painted from inside and acts as a black body as we know that the black body absorbs the lights of all wavelengths.

Similarly, this box absorbs these infrared rays and heats up.    

We also know that the black body in heating up radiates all the lights of varying wavelengths absorbed by it. This box also starts emitting the infrared rays absorbed by it. 

However, the glass sheet surrounding the box doesn’t allow the heat to go out. 

In this way, a glass sheet enables the cooker to entrap heat inside the box.

Making of Solar Cooker

Let us make a box-type solar cooker for household use.

Materials Required:

1. A wooden box having a styrofoam lining inside,

2. Aluminum sheet,

3. Black paint,

4. Mirror,

5. Glass sheet,

6. Hinges,

7. Wooden lid for the box, and 

8. Containers to cook food

Construction: 

Step 1: Take a wooden box and make a box out of the aluminum sheet.

Step 2:  Paint the inner side of the aluminum box with black paint.

Step 3: Place this box inside the wooden box

Step 4: Now, fix the mirror to the lid, and with the help of the hinges, fix the lid to the wooden box.

Step 5: Now, cover the box with a glass sheet.

Step 6: Now, to cook the food, paint the containers in which we wish to cook, and paint these utensils with black color from outside.

Step 7: Place these containers filled with food items inside the box.

Result:

The glass sheet helps in entrapping the heat inside the box and the mirror converges the light onto the box, heats it and the solar cooker is ready to cook the food.

Advantages and Disadvantages of Solar Cooker

Advantages:

1. Pollution-free.

2. They don’t use fuel.

3. Solar energy is freely available.

4. Very low management cost.

Disadvantages:

1. We can use solar energy at a certain time during the day.

2. We cannot use it at night, during the rainy season, or during foggy winters.

3. It is time-consuming as compared to the normal cookers.

Solar Pressure Cooker

Let us make a parabolic solar cooker to understand how solar pressure works.

Materials Required:

1. Take a parabolic dish from the old TataSky receiver.

2. Solar reflective film and cut it into small pieces of equal sizes.

Construction:

1. Now, clean the surface of this dish rec.

2. Paste the reflective films on the entire surface of the receiver as you can see below:

3. Make sure no bubbles are trapped inside the films.

4. Now, connect the reflector on the stand.  

5. Fix a holder in the front of this surface, and place the cooker on this holder.

This is how we can cook the food in the pressure cooker using the parabolic solar cooker.

Result: Parabolic solar cookers converge sunlight to a single point. 

When this point is focused on the bottom of a pressure cooker, it can heat it quickly to very high temperatures.

Solar Cookers and their Significance

Solar cookers are one of the simplest utensils used to cook food. It's safe as well since it does not use fire and is environment-friendly as it does not consume any fuel.  It harnesses the power of the sun to cook food. It is usually designed in the form of a simple box in which you place your food. The box is lined with some kind of reflective metal and covered with glass.  It then uses the energy of the sun to cook your food as per the temperature that you want your food to be cooked in.  The food gets completely cooked. Solar cookers are thus inexpensive, eco-friendly, and easily used.

Search Vedantu for More About Solar Cookers

Vedantu contains Solar Cooker – Explanation, Types, Advantages, and Disadvantages on its platform and right here, on this page. This page gives us major insights into what a solar cooker fundamentally is and how it needs to be used. The types of solar cookers, their making, merits, de-merits, and the manner of constructing one have been described. This information is quite relevant for all students who need to know about solar cookers in a condensed manner.