Successful Solar Oven Cooperation Finland - Kenya

by Kari Silfverberg

The Lions Club of Helsinki Pohjois-Haaga initiated in 2017 a cooperation project for solar oven development with two Kenyan partner organisations:  the Lions Clubs of Kakamega and Greater Nairobi. Funding for the project was provided by all Nordic Lions Clubs together and the International Lions Foundation.  

The first phase of the project was completed in August 2019, and a second phase is being prepared. About 1 500 solar ovens were constructed in Kakamega town during the first phase and distributed to households in Kakamega and selected villages in Kakamega County. Before distribution of the ovens a 2-day solar cooking training programme was arranged for 40 members of local women’s associations and environmental teams, and also a solar oven user manual was produced. About 10 different local dishes were prepared during the training programme, including the main Kenyan dish ugali (maize porridge) and also cakes. The trainers have been responsible for distribution of ovens and user training for the receiving households.  

Advantages of cooking with solar ovens

Various types of solar ovens and other kinds of solar cookers have been developed and used in the south already since the 1970’s, but knowledge of solar cooking technology is still very limited in African countries.  Therefore it is important to initiate projects and distribute solar cooking knowledge to local communities all over Africa, particularly in areas where fuelwood and charcoal consumption is high and deforestation a growing problem.  The main advantages of solar cooking -  particularly using solar ovens, are environmental, economic and health related:  

  • Reduction of the need for fuelwood and charcoal for cooking and thus halting deforestation and forest depletion
  • No need for time-consuming and laborious collection of fuelwood (often the task of young girls)
  • Economic benefit: significant reduction of spending on fuelwood, charcoal, kerosene or electricity bills. Solar radiation is free of charge.
  • Cooking pots do not wear out fast as during cooking with fire.
  • Health benefit for housewives:  cooking free of air pollution by smoke and soot
  • No risk for fire hazard or skin burns or burning the food.
  • Cooking with a solar oven is a safe slow-cooking method, which provides housewives possibilities to do also other tasks while cooking.  
  • A solar oven can take more than one cooking pot, and give possibility to prepare many dishes at the same time.
  • A solar oven can keep the food hot for some hours after completed cooking, when the covering lid has been closed.

Comparisons between different types of solar cookers (solar ovens, parabolic solar grill and panel cookers) where made during the project, and the result was, that the solar oven is the best solar cooker for household use in Kenya, since it is safe, effective, functional and easy to use.  A parabolic solar grill is more effective, but it is more difficult to use and can cause a fire hazard.  A panel cooker is easier to construct, but it has a limited effect.

Some experiences of Kakamega solar project  

The users of the solar ovens in Kakamega have expressed their satisfaction of the functionality of their ovens. Particularly important has been their experience, that cooking of ugali has been easier with the solar oven than using the traditional fuelwood method. Experience has also shown that many dishes (e.g. eggs, potatoes, carrots and other vegetables) can be prepared with only small amounts of water.  Meat dishes are prepared  rather slowly, but without risk of burning.  

Oven construction and function

The solar ovens constructed in Kakamega have a framework of thick (6,5 mm) film-coated plywood, which has been cut into interconnected  pieces, which makes assembly rather easy.  Part of the plywood was donated by Finnish UPM company.  The bottom and walls of the oven have 30 mm rockwool  thermal insulation, and the inside of the oven is made from 0,5 mm aluminium sheet. The bottom panel  is painted black. The transparent lid of the oven is 4 mm thick polycarbonate sheet. Also window glass can be used, but polycarbonate is more durable (does not crack or break).  A silicon rubber band ensures that the transparent lid rests tightly on the oven wall. It is important to prevent heat from escaping from the oven.

The covering lid is made of plywood, and it’s inside has a reflective (glossy) surface.  Both sides of the oven have removable reflective aluminium sheets. The lid (back reflector) and the side reflectors shall during cooking be adjusted so that solar radiation is concentrated inside the oven on the cooking pots, which shall be black painted.  

The temperature inside the oven can reach 150 degrees Celsius during midday in sunny weather. Effective cooking time in Kenya is from about 9 in the morning until 4 in the afternoon.  The effectivity of the oven can be improved if thermal insulation is made thicker and the reflectors made from very glossy material. However, in Africa it is necessary to try to minimize the material costs. In Finland I have built my own solar oven with thicker thermal insulation, and with it I can reach even 180 degrees C during sunny days in summertime.        

The speed of temperature rise in the oven depends on the amount of water in the cooking pots. Temperature rise is slower If they contain much water.  The thermal efficiency of the oven can be improved by placing a flat black-painted stone on the oven bottom to be heated before cooking is started.    

The next stage of Kakamega solar project  

Helsinki Pohjois-Haaga Lions Club received this year a private donation, which provides a possibility to start a new stage of the project. In the second stage there will be some modifications to the solar oven: The framework of the new oven is galvanized iron sheet, which is a strong and reasonably cheap building material. The outer shell is 0,8 mm thick and the inner shell 0,6 mm.  The iron sheets are cut in a metal factory in Nairobi using CAD computer programme. This gives a possibility to assemble the sheets almost without screws, which makes construction fast and easy.

The targeted upper limit for the construction cost is 80 euros per oven. This is affordable for middle income families in Kenya, but too high for low-income families. For them a subsidy will be needed. It has however been estimated that the cost of the solar oven can be recovered already in about half a year due to less expenditure on fuelwood and charcoal.

The long-term target for our Kakamega solar oven project is to make it possible for local small industries to start producing their own solar ovens for sale, and create new employment. This can be possible once the use of solar ovens has become common and their advantages well known.

In the future the LC solar team will also look for possibilities to extend the Kakamega project eg. to Ethiopia.


For more information, contact the author Mr. Kari Silfverberg, email: karisilf@gmail.com