Solar Cooler

The Situation

Almost 1 billion extremely poor people live in rural areas where they are engaged in agricultural activities. A lack of knowledge of post-harvest practices combined with poor infrastructure and no storage facilities result in at least 40% waste in the fresh-produce supply chains in developing countries. 

The Solar Cooler

Together with local entrepreneurs, Mueller developed the Solar Cooler: an off-grid milk cooler for churns, that runs on solar power. The cooling unit enables producers to preserve the quality of the evening milk. This also means less dairy waste and new job opportunities for local entrepreneurs.


  • Through the use of solar power during daytime, an ice layer of 30 mm is formed on each side of the evaporator plate in the solar cooler.
  • The chiller has a cooling capacity of 9.1 kW. The condensing unit has a cooling capacity of 1.4 kWh at 46°C ambient and -15°C evaporating temperature.
  • In the cooler 8 stainless steel milk churns (30 liters each) are placed on a plastic grid. The churns are filled with milk. 8 spare churns are included.
  • With a pump and a spray pipe, the melting ice water is sprayed on the milk cans. This cools the milk back to under 8°C within 3 hours, under 4°C within 5 hours and keeps the milk at the right temperature.
  • The cooler has an isolation of 7 cm.
  • The condensing unit is mounted on the side of the cooler.
  • The cooling unit also works on 220 VAC when electricity is available.

Specifications and Sizing

  • Dimensions cooler in millimeters: 3,750 (length) x 800 (width) x 775 (height).
  • The cooler is filled with water up to 5 cm above the plastic grid.

Our Dairy Farm Partners

We are proud to partner with these leaders in the dairy farming industry. From legacy farms that have thrived through multiple generations to solar cooling in Africa that is providing young children their first taste of cold milk, our equipment is impacting lives around the world.