Cool innovation for a hot world


Phaesun and Solar Cooling Engineering, a spin-off company of the University of Hohenheim, have been developing a modular cooling technologies since 2013. SelfChill implements core components called cooling units, which are powered by photovoltaic modules to generate cold (thermal energy).

The SelfChill Solar Cooling Unit is a hermetically sealed vapor compression heat pump comprising a compressor, condenser, evaporator plate, and control unit. Its low starting current eliminates the need for batteries, but a small, optional battery bank can be used to extend the cooling units’ operation after sunset using surplus energy. Ice is produced as an energy storage medium, ensuring that cold power is always available even when the cooling units are inactive.

Using thermal storage instead of batteries enables high discharge rates, which are essential for cooling in various agricultural value chains. This approach avoids the high costs associated with electronic equipment such as inverters, which are required for traditional cooling applications.


At SelfChill, we pride ourselves on offering a highly flexible concept that covers every aspect of the value chain. Our cooling technology offers a wide range of applications for the rural economy, including cold rooms for horticulture and fruit cultivation, milk cooling for small- to medium-scale applications, ice blocks for fisheries, and other post-harvest processes where cooling is required. Our approach provides significant technical, environmental, economic, and social benefits, including:

  • Self-assembly kits that save on volume, transport costs, and CO2 emissions while keeping added value in target countries.
  • Local assembly using locally sourced materials, reducing the need for long-distance transportation.
  • Easy maintenance, with broken cooling units easily replaced and repaired locally.
  • High cooling power achieved through ice storage and compensation for solar fluctuations.
  • Versatile cooling options, including water, air, and ice packs.
  • COP > 1.5 even at extreme ambient temperatures of 45°C.



Most cooling systems use conventional refrigerants that have a high Global Warming Potential (GWP). Our systems are filled with natural refrigerants such as R-290 and R-600a, which have zero Ozone Depletion Potential (ODP) and ultra-low Global Warming Potential (GWP).

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