Development and evaluation of a hybrid solar-battery powered PCM-integrated portable cold storage system for fruits and vegetables

Abstract Reliable and affordable cold storage is particularly essential for small-scale farmers and vendors in off-grid regions, as it helps reduce post-harvest losses of fruits and vegetables and supports overall food security. The present study develops a 124-litre hybrid Solar-Battery Powered PCM-Integrated Portable Cold Storage (SBP-PCM-PCS) system. The unit uniquely integrates solar photovoltaic power, grid electricity, and PCM-based thermal storage within a vapor compression refrigeration cycle for reliable and energy-efficient cooling. A newly formulated Lauric-Myristic-Dodecanol (LMD) PCM blend with melting and freezing points of 15.6 °C and 8.4 °C, respectively, is employed for the first time in a solar-powered cold storage application. The system’s innovative control strategy utilizes off-peak grid power at night to charge the PCM and solar energy during the day for sustained operation, enhancing thermal stability, reducing compressor runtime, and lowering energy costs, establishing a novel, sustainable, and cost-effective solution for decentralized cold storage. The Experiments were conducted at ambient temperature of about 30 °C to evaluate the performance of the system, under three operating modes: Grid power -only, Grid + PCM, and fully integrated hybrid mode i.e. Solar + PCM + Grid. Performance parameters, including compressor ON–OFF cycle, grid energy saving, cold retention duration, and coefficient of performance were systematically analyzed. It was observed that the integration of PCM reduced compressor ON-time by 4.86%, resulting in 4.61% saving in grid energy. The overall system COP was improved (from 1.80 to 2.10) by 16.7%, and temperature retention time was extended by 4 h compared to the conventional cold storage systems. Furthermore, the solar integration reduces the grid dependence by 26.45%. These findings successfully demonstrate the potential of the SBP-PCM-PCS unit as an energy efficient, portable, and eco-friendly cold storage solution, particularly beneficial for low-income farmers/vegetable vendors advancing both economic viability and environmental sustainability.