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  1. Dan Brigden
  2. Cold chain equipment
  3. Friday, March 10 2017, 10:17 AM

WHO and UNICEF have just published a new evidence brief on solar direct-drive (SDD) vaccine refrigerators and freezers. It includes case studies from Tanzania, Colombia and Kenya, as well as an overview of SDD technology and how to make sure that SDD technology is the right choice. Here's the link:

This is the document summary:

“Solar direct-drive (SDD) refrigerators and freezers can be a good option for vaccine storage in areas without reliable electricity, and many models are now WHO-prequalified. But with little information on SDD field performance currently available, making a case for investing in this new technology can be problematic. This evidence brief provides supply chain managers in low- and middle-income countries with a summary of how recent SDD projects have performed, highlighting problems encountered and the steps that were taken to resolve them. An overview of how SDD technology works, and how to make sure that SDD technology is the right choice, is also provided.”

It provides a nice overview of SDD projects, but for those looking for more detailed guidance on how to implement successful solar-powered vaccine refrigerator and freezer systems, I would also recommend the following much longer WHO-UNICEF publication:

“Introducing solar-powered vaccine refrigerator and freezer systems - A guide for managers in national immunization programmes”

I would be interested to hear the thoughts of other members on the new evidence brief.

PS. If you’re looking for more information on other SDD projects, check out at the following forum discussion, which includes contributions from members regarding SDD projects in Somalia, Ethiopia, Malawi, and Rwanda.

Kshem Prasad Accepted Answer

I would like to add to the "Complementarity " mentionned by Rafael.

The common thinking is to blindly replace the absorption fridges with SDDs. However, in most countries, the rainy season may render difficultthe funtionning of SDDs, especially if there is an intense monsoon season. In those days or weeks one can use the existing absorption refrigerators as backup. Thus the health cewntre may require just around 10% of its current need of gas or kerosene, while ensuring the correct storage of vaccines.

By completing removing the absorption refrigerators by SDD, one may not gain except the space occupied by it.

The experience about solarchill in 2007 and SDD from 2013 has been very positive in Colombia where we have 300 equipments SDD working in different kind of climates and environments, jungle, desert, coast, island, mountain. The best equipment is who have freezer and refrigeraror combined. One topic very important is must have a responsable to take care the equipment and get the training to the people of the comunity, not only to vaccinator.

The refrigerator by absortion and SDD are complemented and each of them works in diferent situations. Both are very useful.

Kshem Prasad Accepted Answer

This is a very useful compilation of field expereince and learning for qality intallation and sustainability of SDDs. some of the key issues emerging are : 1) Need for adequate user training, 2) need for proper technician training and 3) ensuring adequate and continuous funding for maintenance.

It should be noted that under the Gavi's CEEOP, the training of users and technicians is included within the bundling of the equpment. The countries would do well to benifit from this at least for the intial set of equipmnent if not all. For this the EPI should identify the technicians and staff to be trained.

As for securing funding and its sustainability for preventive and curative maintenance, all countries switching from the Gas / Kerosene based equipment should compute their annual saving on fuel and its transport (which is now saved for every year for the next decade). The total annual funding required for the preventive and curative maintenance would be just a fraction of this. It would be wise and judicious if they would set aside this budget for the sustainability of the SDDs, while making the big saving from the Gas/kerosene.

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