What service life do you think vaccine refrigerators should be able to provide? For example, some products may suggest a 10 year life while others suggest longer, with typical repairs. PQS requires a 2 year warranty for a vaccine fridge.
Solar powered vaccine fridge systems require solar electric modules (minimum 20 year warranty is typical and 20 year is required by PQS). Most also have batteries (5 year warranty per PQS).