<b>Development of a Portable and Low-Cost Modular Solar Dryer with Interlocking Panels</b>

A modular solar dryer of 10 kg holding capacity featuring an interlocking panel design was developed and evaluated for drying agricultural produce. The dryer was constructed using polycarbonate sheets, enabling easy assembly and disassembly. Performance evaluation included no-load and load testing using amla (Phyllanthus emblica) slices (10-15 mm thickness) to assess temperature variations, relative humidity and thermal efficiency. The no-load test showed that the dryer-maintained 15°C-20°C higher temperatures with 20%-30% lower relative humidity compared to ambient condition. During load testing, the drying rate peaked at the initial hours and progressively decreased as moisture content decreased. The top tray exhibited superior drying performance due to enhanced heat exposure. The six-tray modular dryer (capital cost of ₹10,100) achieved safe moisture levels (<10% wb) within 15 operating hours over three days. Economic analysis demonstrated high internal rate of return (91.8% with labour cost) and short payback period (1.65 years). The enclosed design minimized contamination, ensuring improved product quality. The results indicated that this modular solar dryer offers a flexible, cost-effective, and portable solution suitable for small-scale farmers and food processors, ensuring better energy utilization and product quality.