A Comprehensive Review on Solar Dryers for Perishable Agro-Products: Aspects of Technological Advancements, Techno-Economic Performance, and Environmental Impacts

Abstract

Solar dryers (SDs) are sustainable and environment-friendly options for reducing the moisture level of perishable agricultural products. These dryers use renewable energy sources and reduce greenhouse gas emissions as compared to the conventional fossil fuel-based drying methods. This review examines the technological advancements, construction, techno-economic performance, environmental impacts, and smart control systems of SDs. Technological progress showed how the solar drying system is shifting toward a robust and efficient alternative to industrial dryers. Different designs, types, and modifications are assessed to illustrate the recent development trend in SDs. The technical performances of the SDs prove their potential to provide an eco-friendly solution for drying applications in agriculture. The long-term economic benefits due to their low operating costs and high benefit–cost ratio make SDs viable for farmers and industrialists. Assessments of environmental parameters reveal that SDs significantly reduce the carbon footprint and mitigate CO₂ emission throughout their lifespan. The control systems with smart and modern interfaces such as microcontrollers, sensors, and Internet of Things (IoT) enhance the efficiency of operation by enabling real-time monitoring and automation. However, the SDs face great challenges in unfavorable weather conditions which must be addressed to upscale their adoption and implementation. A SWOT analysis clearly illustrates the key issues associated with SDs that need to be properly dealt with. Incentives and regulations taken on national and international levels can successfully overcome the technical barriers of the SDs and present them as a stand-alone system for reducing postharvest losses.