Solar (PV) refrigeration of vaccines
Practical Action
• reduced logistical problems arising from non-availability of working refrigerators
• reduced logistical problems arising from lower vaccine losses.
The above operational advantages of introducing solar refrigerators into the cold chain indicate
that solar refrigerators can provide a more sustainable vaccine cold chain.
It should be noted however, that as each system is site specific, more time is necessary for
planning and implementing a project with solar refrigerators.
User training demands are also higher since a new technology is being introduced.
Comparative costs
A true comparison of solar refrigerators and comparable kerosene and bottled gas fuelled
refrigerators can only be made through a life-cycle cost analysis.
A solar photovoltaic refrigerator cabinet only is likely to cost around US $1300 - 2600 (with the
complete system costing around US $3000 - 5000) and will cost more to install than a kerosene
unit. A kerosene refrigerator will cost only US $650 - 1300 but will use 0.5 - 1.4 litres of fuel
per day, require frequent maintenance and have a shorter life. In general, life-cycle costs are
approximately the same for solar and kerosene refrigerators, but because of their greater reliability
and resultant savings in wasted vaccine, solar refrigerators are the preferred option.
The technology
Refrigerator
Photovoltaic refrigerators operate on the same principle as normal compression refrigerators but
incorporate low voltage (12 or 24v) dc compressors and motors, rather than mains voltage ac
types. A photovoltaic refrigerator has higher levels of insulation around the storage compartments
to maximise energy efficiency, a battery bank for electricity storage, a battery charge regulator and
a controller which converts the power from the battery to a form required by the compressor
motor.
A typical refrigerator layout is as shown below (Figure 1). Most refrigerators include a freezer
compartment for ice pack freezing. Other systems have separate units to provide solely for
refrigeration or freezing. Available sizes range between 10 and 85 litres of vaccine storage
capacity with ice production rates of up to 6.4 kg per 24 hours.
Figure 1: A
typical
refrigerator
layout
2