Solar Cooking

The Democratic Republic of Congo is among the developing countries in Africa where fire wood and charcoal are mainly the cooking energy. The techniques of Integrated Solar Cooking (ISC) is less known. However, they permit to get economic and ecological products of better quality. The country has much sunshine. Solar cookers and Dryers process food in an ecological way and without cost since the sunshine is a gift from God. The integrated solar cooking appliances and technologies are the unique means both to save the household expenses allocated to the cooking energy and to improve the livelihood, health of people and save the environment.

Training how to cook with a box solar cooker

What does solar cooker mean?

A solar cooker, or solar oven, is a device which uses the energy of sunlight to heat food or drink to cook it or sterilize it. High-tech versions, for example electric ovens powered by solar cells, are possible, and have some advantages such as being able to work in diffuse light.

Panel solar cooker

Box solar cooker frying meat

What is a solar cooker and how does it work?

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.

Diverse types of integrated solar cookers

Teaching Kelvin how to cook with solar

What is the use of solar cooker?

A solar cooker converts solar energy into heat, which is used to cook food kept in the cooking utensil. Solar cookers also enable some significant processes such as pasteurization and sterilization.

Box and panel solar cookers

Heat retaining baskets

What are the disadvantages of a solar cooker?

Disadvantages of a solar cooker : The cooking is slow.  It connot be used at all times.  A solar cooker can perform only limited functions.  Solar cookers have limited utility at the places where sunlight is less as in polar regions or where there are too much rains

How to use a solar cooker

In order to have the best heating conditions, the shadow of the wooden bar should be parallel to the band in the middle of the cooker.

The reflection of the sun has to go into the solar cooker.

Instructions for cooking:

1. Put the solar cooker into the sun approximately one hour before you begin to cook in order to heat it up to 100 degrees or more.

2. Use thin-walled black pots to cook. Aluminium pots are okay. Use only “food safe” and “heat resistant” paint to paint the pots. For example, use black varnish (car paint) or use special paint for solar cookers. (Other paints can develop toxic gases).

3. Use 1/3 less water than usual if you cook rice or sauces

4. When cooking, try to open the oven as rarely as possible. Every time you open the dor, the temperature drops.

5. It takes more time to cook in a solar cooker than in conventional ovens. You don’t have to stir, as the food can not scorch (burn) in the solar cooker.

conical solar cooker

How to make a Solar Box

 The Solar Box is a double-walled box consisting of the following elements (see the drawings and photo’s for details): - an outer box from 10 mm plywood with (outer) dimensions 60,0 cm x 50,0 cm x 35,0 cm; the upper edge is reinforced internally by bars of 18 mm x 18 mm - an inner box from 10 mm plywood with (outer) dimensions 54,0 cm x 44,0 cm x 32,0 cm; the inner walls and bottom are covered with reflecting aluminium foil; the inner box rests on 20 mm high cubes1 in the outer box; in the inner box a 50 cm x 40 cm aluminium or iron plate of 1 mm thickness, which has been painted black, rests on 20 mm high cubes; the plate supports the cooking pan, which is also painted black - a lid consisting of a 20 mm thick , in which two 2 mm thick glass plates, kept apart by 16 mm high spacers, and covered on both sides by 3 mm thick plywood frames; the lid is connected to the outer box by 2 hinges - a 60,0 cm x 50,0 cm cover plate/reflector of 10 mm plywood connected to the lid by 2 hinges, which can be put at various angles with a hook; the inner side of the lid is covered with reflecting aluminium foil. The reflecting aluminium foil on the inner side of the inner box is used to reflect the incoming sun light as much as possible onto the pan and plate. It also reflects the heat radiation emitted by the pan back to it. The black plate in the inner box is used to absorb the incoming sun light as well as possible and to transfer the heat to the pan. By putting the reflecting cover plate at an angle of 80 to 100 degrees the sunlight that hits that plate when the sun is not located right above you, can be directed as much as possible onto the pan and plate. The Solar Box can handle 1 large pot (until appr. 30 cm diameter and 24 cm height) or 2 smaller pots (diameter 20 cm and height 20 cm). Cooking time for, e.g., rice, vegetables, fish is 1-2 hours under a clear sky. The use of a hay basket is recommended, e.g., for finishing the cooking of rice or keeping dishes warm.

Building a solar box

outer box

the full box

Help us promote clean cooking

Solar cooking is worth to reduce pollution and mitigate climate change