Solar-Powered Cold Storage Technology: A Sustainable Energy Solution for Preservation of Fruits and Vegetables

Electricity supply from the national grid in rural communities in Nigeria is rarely available, making it practically difficult for farmers to preserve their fresh commodities. Poor cold chain infrastructure is a major contributor to the high postharvest losses of fruits and vegetables, which are estimated to be about 50%. While solar-powered cold storage offers great potential in providing sustainable energy for cutting down the losses during transportation and storage, conventional designs face challenges such as battery drain, unstable temperature control, low humidity, and dependence on imported components. To address these limitations, a 7.2 m³ (250 kg) solar-powered cold storage system (SCSS) with a thermal storage unit and a remote monitoring system for temperature was developed at the Nigerian Stored Products Research Institute (NSPRI) using locally sourced components. The system enables real-time monitoring of chamber conditions and energy inputs, thus ensuring that sufficiently low temperatures and high relative humidities are maintained to preserve stored commodities. The performance of the system was evaluated with tomato. Test results showed an average daily ice production of 11.25 kg and a coefficient of performance of 2.1 (210% efficiency). The system also maintained 10–12 °C temperature and 80–95% relative humidity, with tomato stored for 7 days with in-crate values averaging 9.4 °C and 93%. The thermal storage unit ensures continuous cooling even during cloudy days, thus minimizing battery use and reducing the cost of operation. The solar-powered cold room offers a sustainable and energy-efficient solution for preserving fresh agricultural commodities, particularly in off-grid areas. Keywords: Solar cold storage, Sustainable energy, preservation, postharvest losses.