Achieving off-grid refrigeration in remote areas: A solar-powered vapor compression refrigerator prototype with PCM integration

The availability of vaccines, medicines, and perishable goods in remote or off-grid areas remains a formidable
challenge. Integrating solar photovoltaic (PV) systems with refrigeration technology has emerged as a promising
solution to address this critical need. This paper presents an autonomous solar-powered refrigerator prototype for
off-grid refrigeration in remote areas utilising renewable energy. The system comprises a 160 W photovoltaic
module, a 12/24 V DC compressor refrigerator, a lead-acid battery, and a Maximum Power Point Tracking
(MPPT) controller. Its main feature is complete autonomy from the electricity grid, thanks to its standalone
configuration. An experimental campaign evaluated the system’s behaviour in the laboratory for 24 h at different
set-point temperatures. A water-based Phase Change Material (PCM) was implemented to improve its autonomy
in severe outdoor conditions. A further experimental campaign emulated the functioning of the prototype while
managing the temperature of a sample solution whose melting temperature was equal to – 21 ◦C to ensure its
liquid state during the tests. The target range for preserving the sample was defined at ± 1 ◦C. Several real
conditions have been considered, such as higher cooling loads realised through 21 litres of additional thermal
mass in the refrigerator and pick and place conditions for simulating the opening and closing of the door. The
results demonstrate that the solar refrigerator prototype achieves complete autonomy from the electricity grid,
paving the way for solutions for preserving perishable goods such as medicines and food in unelectrified areas.
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