The sun is the most important source of heat and light in the universe. During primitive times, the sun was solely used for its heat and light for all day to day activities, when there was no electricity. With increased usage of fossil fuel and thermal electricity, there is now a risk of global warming. It is being feared that if Earth progresses at the rate at which it is currently moving on, there will not be much of resources left for our future generations. All this has led the world incline towards alternative sources of power. While wind and hydro energy are also making progress, it is solar energy that has become the favoured one amongst masses, mainly due to its increased affordability.

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What is a Solar Dryer

A solar dryer is another application of solar energy, used immensely in the food and agriculture industry. Though sun is still used as the direct source for drying food items and clothes in certain parts of the world. An indirect source of solar power can also be used for the same purpose in the form of a solar dryer. The main disadvantage of drying directly under the sun is contamination – dirt, animals, insects etc. Also there is a fear of sudden change in weather conditions like wind or rain.

When using a solar dryer, you do not have to worry about all this!

A Solar Dryer for drying cocoa seeds

Types of Solar Dryer

A solar dryer can most conveniently be classified as direct or indirect.

Direct Solar Dryer – The item to be dried is exposed directly to solar radiation through a transparent material that covers the structure. The heat generated from the solar energy is used to dry the crops or food items and also heats up the surroundings. The main disadvantage of using the direct mode is that the heat that will be absorbed by the item cannot be controlled. Available in many sizes, ranging from kilograms to metric tons, the simplicity of the product and its affordability are its USP.

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Indirect Solar Dryer – As the name suggests, this method does not expose the crop directly to the sunlight. The solar radiation is absorbed and converted into heat by another surface (like a black top) usually called the collector. Air that will be used for drying is passed over this surface and gets heated, which is then used to dry the food item inside the dryer. The main advantage of indirect mode of drying is that the temperatures can be controlled. The sizes can vary from kilograms to metric tons, but it is expensive and more complex to construct when compared to direct solar dryers.

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These are also commonly referred to as food, cloth or crop dryer, based on the items used for drying using the Solar Dryer. Many people can assemble/ construct a solar dryer with the help of DIY instructions available on the internet. The image shown above is self explanatory. Solar Dryer will find increased applications in the food, agriculture and plantation industries where food and crop items need to be dried before using. It helps in maintaining the quality of these items without contamination fears. In economies, where people hardly have power for their daily life, these devices will help a great deal in reducing the load on the main grid, and electricity from the grid can be used for other purposes.