Solar hybrid dryers for fruits, vegetables, and fish: A comprehensive review on constructional features and techno-economic-environmental analysis

Solar dryers are widely used to reduce moisture levels of fruits, vegetables, and fish, but they are not capable of committing to continuous and fast operation. A solar hybrid dryer (SHD) excels the limitations of conventional solar drying with the help of an auxiliary heating unit. This review delves into a comprehensive overview on drying requirements and configurations of different SHDs, their respective performance indices, and advanced monitoring system integrations etc. The technical performance indices obtained from different studies exhibit the competency of SHDs to fossil-fueled dryers. Moreover, the advancements in communication and sensing technologies have integrated user-oriented real-time control and automation systems in SHDs. Financial viability is ensured through a systematic analysis of different economic parameters. Assessing the environmental impacts caused by SHDs have showed as a sustainable way of processing food products. The studies associated with SHDs show tremendous scopes of reducing postharvest losses of nutrient-enriched crops such as, fruits, vegetables, and fish. Nevertheless, some techno-economic barriers are also noticed in this review, which can be mitigated by proper incentives and regulations. However, application and adoption of solar hybrid dryers will be able to provide nutritious crops year-round via sustainable and clean energy utilization.