Cooling solution for small scale dairy farms and milk collection center


Our decentralized solar cooling solution was developed for small dairy farmers and milk bars in East Africa, in the framework of the Reload Project lead by the University of Kassel, Agrartechnik Witzenhausen.

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The aim of our work was to develop a solar powered milk cooling solution for small scale applications along the milk value chain in East Africa. The target user group are dairy farmers, small cooperatives of dairy farmers, milk bars and small milk collection centers.

Unpasteurized milk is a highly perishable product and needs to be chilled rapidly in order to be able to store it and transport it.

Our device can help users who either do not have enough milk to tranport it each time it is freshly milked, who are too far from the next dairy to transport un-chilled milk, who sell locally or run who a milk bar needing to chill milk waiting for customers.

We have used a standard cooling device: a solar freezer from STECA (PF240) - and converted it into a milk chiller that can handle ~ 40ltr of milk per day. For example 20ltr in the morning and 20ltr in the evening. The milk is cooled down to 4 °C in 2.4 hours and then remains at this temperature until it is transported. The original, battery operated, device from Steca is not able to cool down a large amount as quickly as required by dairy standards. We designed a battery less system that stores energy in form of ice. The ice storage allows cooling round the clock (24h) and boosts the cooling power of the freezer so that the milk can be chilled in the targeted time.
Excess energy is made useable in form of hot water and adds benefits for the users, for example for cleaning of the milk containers.

Our innovative electronic control unit manages 3 crucial functions: it prevents the milk from freezing, it provides the high starting current of the compressor of the freezer without the use of batteries, it manages excess energy and turns it into hot water. The hot water is produced and stored in an in insulated tank, preventing heat losses.

The milk containers and the ice cartridge have a geometry that allows easy cleaning (which is an issue for small scale dairy set-ups). The ice packs do not come in contact with the milk directly, thus cleaning requirements are minimized. The design of the ice packs allows local reproduction with very simple means, even by the end users.

Currently the device is undergoing field testing at the Gilford Dairy Institute, University of Egerton, Kenya.



media coverage:

Online Article in Top-Energy News

Decentralized solar cooling solution is amoungst the finanlists for the 2015 Off-Grid Award by Phaesun