Sun is a cheap source of energy. Energy needed for food processing purposes. Some intuitive individuals are able to cook rice and other dishes using sunlight. Rays are reflected, using special device, and directed to the cooking vessel. The popular food processing use of sun is the sun drying. Commodities such as fruits, meat and fish are sliced, arranged on trays and placed under the sun until sufficiently dried. It is the simplest and the cheapest among drying methods but is also most the disadvantageous.
1) The sun itself is a major disadvantage. The drying can only be done effectively from 9 am to 4 pm. The rest of time is idle. It should be done in open field. Trees, buildings and other structures may block sunlight and hinder the drying process. Cloud formation will also deny sunlight. Rainy and stormy days will completely deny drying.
2) Exposure to dirts, microbes and animals. Unless the commodity is placed inside a shielded equipment,glass or thick plastic, getting dirt and microbes from surrounding environment is likely. Some never want an enclosure cause it add to investment cost and hinder the airflow and makes the drying slower. Animals like dogs, cats and rodents have an easy access to the commodity. They are always ready to get some of your precious fish.
3) The idle time in between drying sessions allow the growth of unwanted microorganisms.
4) In case of open sun drying, sudden rains and strong winds might completely ruin the whole batch.
5) Unrepeatable results. Some parameters could not be set, like dry 50 kilograms of fish for five days. The parameter might be attainable but often not. The reason – read disadvantages above.