Rather than using batteries to power the fridges through the night, these use direct-drive systems to store coldness. The direct-drive technology works best because it removes the one element that is the most frequent cause of failure in solar refrigerators – the battery. It is for this reason that these fridges are being recommended by World Health Organisation.

Saffa Kamara, an immunization officer with UNICEF in Sierra Leone, says the fridges are “far, far better” than earlier solar models, gas-powered ones or even conventional fridges run off a generator.

In countries across sub-Saharan Africa, other vaccinations are easier to store because they only need standard refrigerators. However, even that can be something of a challenge in outlying areas – and in fact, even in some urban areas. It is believed that only 1 in 4 people in Sierra Leone have power and is even lower in rural areas.

Read more: ESI Africa