Effectiveness of solar-powered cold storage for fresh produce preservation in remote areas

Abstract:

Can off-grid farming communities hold their fresh produce long enough to reach a paying market? That question shaped this research, which tested a 1.5 ton capacity solar-powered cold storage unit installed in three remote villages of the Nakuru County between March 2022 and February 2023. The unit combined a 2 kW photovoltaic array, a 10 kWh lithium-iron-phosphate battery bank and a variable-speed vapour-compression chiller to hold chamber air at 4-6 °C with 85% relative humidity. Five locally grown commodities - tomato, spinach, okra, table grapes and coriander - were stored in parallel under ambient conditions, with observations taken every 48 hours. Shelf life extended by 2.9 to 3.9 times across commodities, with grapes reaching 13.8 days against 4.1 at ambient. Physiological loss in weight dropped from 11.7% to 2.8% for tomato after nine days, and ascorbic acid retention improved by 42.6% in coriander. Benefit-cost analysis returned a ratio of 1.84 over seven years, with a payback period close to 3.6 years. The unit ran autonomously for 21 hours per day on average and coped with rainy-season cloud spells without cold-chain breakdown, suggesting that decentralised solar cooling can realistically plug the post-harvest gap facing smallholders without grid connectivity.