Solar cookers for Africa
by Margaret Bennett
Solar cookers have been with us in various designs for millennia. As an environmentally friendly and cheaper option for rural communities in sunny countries, the Sunstove Organisation has a decade's experience in producing solar cookers.
The latest model Sunstove 2000 was released in South Africa last year and has already sold more than 1000 cookers. The Sunstove organisation was invited to exhibit their product at the world Expo in Hannover, Germany last year. They were one of only three South African projects taking part in the "Projects around the world" section - The Sustainable village. They have now reached the top 50 from a thousand projects entered for the Energy Globe Award to be presented in Austria at the Renewable Energy expo in early March. Here Margaret Bennett explains how the solar cooker came to South Africa, how it has evolved, demonstrating how innovative ideas can see the light of day.
In 1989 at a World Conference of the World Association of Girl Guides and Girl Scouts a delegation from Solar Box Cookers International, California, presented their cardboard solar cooker. It was suggested that sunny countries such as South Africa should take up this idea and, through our members (girls and women) the Girl Guides should attempt to spread the concept.
As an Adult Trainer within the Association, I was tasked with taking this idea out to the country.
The initial plan was to assist rural woman with the making of their own solar cooker and then to have this knowledge passed on to neighbours. The idea did not take off as expected, mostly due to a lack of easily available materials and expertise. This approach was abandoned and I looked into designing and manufacturing the solar cookers myself. I approached the largest cardboard box manufacturer, Nampak, for assistance. I asked them to make a kit solar box that could be sent out and assembled on site. They put in a huge amount of time and effort perfecting the bonding of aluminium foil to heavy-duty cardboard and produced a really great cooker.
The trouble was that cardboard of that quality was not cheap. Even back in 1990 the cost of it was R80. We came across a lot of resistance to buying a cardboard solar cooker for this price. The design itself proved to be a problem. The large reflector held up by a prop stick was a huge nuisance. It either fell flat or acted as a sail and carried the cooker away in the wind! It was difficult to train inexperienced users to align it properly around 2 axes - and if it wasn't focused, it didn't cook.
At that juncture, serendipity came into force! Dick Wareham had been trying himself to find a solar cooker for rural people. As an industrialist with long-standing connections with this country he had seen the need for alternative energy for cooking. We were introduced by Fibreglass S.A. where we had both been looking for insulation material and from then on worked together.
Mr. Wareham and I had independently arrived at the same conclusion - reflectors are nothing but trouble. So he designed a model without a reflector but with sloped sides and tilted window to compensate. We made this one round, out of PET and 900 were distributed via the Girl Guides Association. Many of that model are still in use today, but in trying to send them around the country we discovered that our round Sunstove did not travel very well. They distorted in transit and we lost a lot of credibility because of this.
Dick Wareham decided to put up the money to make a mould (for blow moulding) for a really sturdy Sunstove that would withstand rough handling during transport and actually stack together to cut costs. This was about R45,000. Mr. Wareham did not expect to recoup this money from sales of the Sunstove - he did it as a philanthropic gesture to move the project forward.
And it has gone forward. Since 1990 we have sold more than 10,000 of this model of the Sunstove. We average sales of about 100 a month. Our customers have turned out to be farmers' Co-ops, enterprises connected with renewable energy in general, interested 'greenies' - and hopeful entrepreneurs of all descriptions! All of this without benefit of advertising but rather from random and ad hoc publicity in various media.
Through all this time it has been our ethos to keep the price of a Sunstove to the very minimum. - so that the really needy people can afford it. Today it costs R135 ex factory . This low price is due firstly to our material suppliers, who give us their best prices because they appreciate what we are doing and, secondly because we use recycled materials to a great extent.
In the year 2000 we were forced to have another mould made to accommodate the most readily available size of re-usable aluminium printing plate we needed. Whilst this was being done we took the opportunity to improve the design of the lid as the previous hinged one had been criticised for deteriorating in the sun and becoming aesthetically unpleasing.
We have sold nearly 1,000 of this 'Sunstove 2000' Dr. Bernhard Scheffler of the University of Pretoria's Department. of Physics, who has tested their products over the years, reports that this model performs even better than the previous one. It is certainly easier to make - the lid is so much simpler - and it travels very well. I send these Sunstoves all over the country - and the world - by post. They weigh only 5kg.
We are a very small scale operation. Our overheads are minimal. We have no factory space. We run on a shoestring. However, we are proud of our achievements to date. There is no other sustainable solar cooker programme anywhere on the scale we have reached.
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