Crop drying is essential for preservation in agricultural applications. It is performed either using fossil
fuels in an artificial mechanical drying process or by placing the crop under the open sun. The first
method is costly and has a negative impact on the environment, while the second method is totally
dependent on the weather. By contrast, using a solar dryer is comparatively cheaper and more efficient.
Some solar dryers run without electrical grid power or fossil fuels. This paper presents the state of
various kinds of solar dryers that are widely used today. The indirect, direct, and mixed mode dryers that
have shown potential in drying agricultural products in the tropical and subtropical countries are
discussed. Aside from identifying the active and passive mode solar dryers, we also highlight the
environmental influence on solar energy (harnessing) that plays a vital role in the solar drying sector.
This paper also presents the related technologies that can help improve existing solar dryers.
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