Solar cookers

Table of Contents
What is a solar cooker? Who uses solar cookers? Advantages Disadvantages Devices Related topics External links and references Contributors

[top] [end]What is a solar cooker?

Most solar cookers work on basic principles: sunlight is converted to heat energy that is retained for cooking. A solar cooker needs an outdoor spot that is sunny for several hours and protected from strong wind, and where food will be safe. Solar cookers don't work at night or on cloudy days. Dark surfaces get very hot in sunlight, whereas light surfaces don't. Food cooks best in dark, shallow, thin metal pots with dark, tight-fitting lids to hold in heat and moisture. A transparent heat trap around the dark pot lets in sunlight, but keeps in the heat. This is a clear, heat-resistant plastic bag or large inverted glass bowl (in panel cookers) or an insulated box with a glass or plastic window (in box cookers). Curved concentrator cookers typically don't require a heat trap. One or more shiny surfaces reflect extra sunlight onto the pot, increasing its heat potential [Wikipedia, 2007]. Solar energy is fairly low grade energy, so all solar collectors are designed to either collect and retain the solar energy, or focus the solar energy into a small area of high intensity.

[top] [end]Who uses solar cookers?

China and India are among several countries promoting the use of solar cookers. A simple box-type cooker and a parabolic concentrating type cooker are among the common models deployed. Efforts have also been made to develop solar cookers for institutional use. In India some 450,000 box type cookers have been installed. The world's largest solar cooking system -capable of preparing meals for 10,000 persons twice a day- was installed in 1999 in Taleti in Rajasthan, India [TERI, 1996/97; MNCES, 1999]. In China some 100,000 concentrator-type cookers have been deployed [Wentzel, 1995].

[top] [end]Advantages

Solar cooking offers many advantages over traditional cooking methods:

- Smoke free cooking

- Slow cooking "sweats" the food so that little or no water needs to be added and the flavour is undiluted.

- Stirring is not required because the heat delivered to the bottom of the pot is not intense enough to burn the food.

- The pots require less scrubbing because they are not caked with soot.

- Attention to the cooking food is only required every hour or so to track the path of the sun.

- Although solar cooking can take twice as long as traditional methods, the time is offset by freedom from the need to forage or purchase fuel.

- Physical injury caused by carrying heavy loads of fuel wood is alleviated and child mortality is reduced by decreasing the risk of maiming from falling into cooking fires.

- Solar cookers are usually designed to last 10 years or more.

- The fuel is free.

[top] [end]Disadvantages

Solar cooking also have disadvantages over traditional cooking methods:

- Only cook when it is sunny.

- It is necessary to store the cooker in rainy season.

- Box cookers take time to heat up.

- Parabolic cookers need frequent adjustment.

[top] [end]Devices

The three most common types of solar cookers are heat-trap boxes, curved concentrators (parabolics) and panel cookers. Hundreds, if not thousands, of variations on these basic types exist. Additionally, several large-scale solar cooking systems have been developed to meet the needs of institutions worldwide.

[top] [end]Box cookers

Box cookers cook at moderate to high temperatures and often accommodate multiple pots. Worldwide, they are the most widespread. There are several hundred thousand in India alone.

[top] [end]Curved concentrator cookers

Curved concentrator cookers, or "parabolics," cook fast at high temperatures, but require frequent adjustment and supervision for safe operation. Several hundred thousand exist, mainly in China. They are especially useful for large-scale institutional cooking.

[top] [end]Panel cookers

Panel cookers incorporate elements of box and curved concentrator cookers. They are simple and relatively inexpensive to buy or produce. Solar Cookers International's "CooKit" is the most widely used combination cooker.

[top] [end]Related topics

[top] [end]External links and references

www.sunspot.org.uk;

www.peruchildrenstrust.org.uk;

www.sungravity.com;

www.solarcooking.org;

www.itdg.org (Practical Action);

www.sunspot.org.uk/ewb;

[top] [end]Contributors

User:Grant Ballard-Tremeer 1 September 2003
User: Jose E. Villalobos-Enciso? 09 June 2007

Categories: Solar Energy| Solar Cookers

edit this page

Page created: 01 September 2003; Last edited: 11 July 2007; Version: 3
Knowledge Bank text is available under the terms of the GNU Free Documentation License.

Pagename: SolarCooker @HEDON: TCAA