Solar Cooler

Cooling units for small scale dairy producers, enabling them to preserve the quality of fresh dairy. This leads to job generation for local entrepreneurs and less dairy waste.

The Situation

Almost 1 billion people are living in extremely poor conditions in rural areas of the world. They are engaged in agricultural activities, but a lack of knowledge around post-harvest practices, combined with poor infrastructure and no storage facilities results in at least 40% waste in the fresh food supply in developing countries. Cold storage chains for dairy products in rural areas could have a tremendously positive effect on the income of small farmers in developing countries. As it stands now, they milk their herds twice a day and often the evening milk is lost because it spoils by morning, when the farmer is first able to take the milk to a collection point. The challenge: develop a cooling solution for the evening milk of the farmers.

The Solar Cooler

Collaborating with some of our valued partners, Mueller developed the Solar Cooler: an off-grid milk cooler for churns, that runs on solar power. The cooling unit enables producers to cool down up to 240 liters of their fresh milk to the desired temperature. This preserves the quality of the dairy for the consumers, means less dairy waste and an increase in income for the farmer.


  • 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.


Finding the right equipment that fits within your budget can be daunting. At Paul Mueller Company, we understand your needs. That’s why we offer Leasing options that give you more flexibility.

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Our Dairy Partners

Amazing brands producing amazing products!  We are proud to partner with these respected leading companies in the Dairy Foods Industry and help them grow offerings to their valued customers.