In regions with limited energy infrastructure, there is a strong demand for reliable cooling solutions to reduce food losses, establish cold chains, and increase local income.
Solar powered off-grid cold rooms require low cooling capacities combined with comparatively high storage capacities. The specific requirements vary significantly depending on the application and cold room size.
Within this project, a modular cold thermal energy storage system based on latent heat storage (water ice) was developed. Compared to sensible storage systems, this approach offers a significantly higher energy density and is therefore particularly suitable for compact, energy-autonomous applications.
The development focused on a system that is:
- cost-effective
- modular and scalable (stackable design)
- indirectly cooled,
while requiring only minimal secondary heat transfer fluid and being compatible with natural, flammable refrigerants.
A key objective was ease of use:
- Installation and maintenance are possible without advanced refrigeration expertise
- Integration of an air cooler and a control unit for connection to an energy management system
An innovative aspect is the use of PET bottles for encapsulating the storage medium. This approach enables:
- significant cost reduction
- utilization of locally available materials
- contribution to recycling efforts
To support system design, a web-based application for dimensioning cold rooms and storage systems in solar cooling setups was also developed.
A prototype (thermal storage module) was successfully tested and optimized in a solar-powered test stand.
Next steps:
- Technology transfer to local manufacturers
- Implementation and validation in a pilot project
Technical data: <ThermalStorageModule_30kWh_20260323.pdf>