Folding Solar Refrigerator Using Peltier Module

Conventional vapour-compression refrigerators are unsuitable for rural clinics, disaster-relief camps, and field operations that lack a reliable grid connection, since they depend on compressors, refrigerants, and continuous mains power. This paper presents the design, fabrication, and testing of a foldable solarpowered refrigerator built around solid-state Peltier (thermoelectric) modules. A 40 W monocrystalline solar panel charges a 12 V rechargeable battery through a pulse-width-modulation charge controller, giving the unit uninterrupted operation during cloudy periods and after sunset. Four TEC1-12706 thermoelectric modules, each paired with an aluminium heat sink and a DC exhaust fan, remove heat from a collapsible, foam-insulated cooling chamber that folds flat for transport and storage. An ESP32 microcontroller reads chamber temperature and humidity from a DHT11 sensor and publishes live temperature, humidity, and battery-voltage readings to a Wi-Fi-based Internet-of-Things dashboard, allowing remote supervision without opening the chamber. The prototype was tested under ambient conditions of 30-34°C at Kashti, Maharashtra, with the chamber loaded and unloaded. Results show the chamber temperature falling from ambient to below 10°C within about an hour of continuous operation, with the coefficient of performance and cool-down time depending on ambient temperature and thermal load. The folding chassis reduced the stored volume by more than half relative to a rigid enclosure of equal capacity. The system demonstrates that a compressor-free, solar-charged thermoelectric refrigerator with IoT monitoring is a practical, portable, and environmentally friendly cooling option for off-grid healthcare, food preservation, and emergency-response applications

Keywords - Solar Energy, Peltier Module (TEC1-12706), Thermoelectric Refrigeration, IoT Monitoring, Portable Cooling System