According to a study (Martinez et al., 1991) where a survey was carried out with information given by
researchers specialised in solar cooling, I9 possible technologies were identified for solar refrigeration. The
photovoltaic I vapour-compression systems and the photovoltaic / thermoelectric have predominated in the
application of small refrigerators for medical use in isolated areas like vaccine conservation where high
system cost is justified. Solar thermal systems such as flat plate collectors and lithium bromide/water
absorption cooling systems are in the stage of pre-production and commercial introduction, also for small
capacities. Five companies are not fabricating systems due to a lack of a market for their products. The
global efficiency of solar refrigeration systems oscillated between 7% and 20% and differs because of
insolation conditions. Critoph, (1991) mentions that under sufficient insolation (5.5 kWh/m2-day) the
majority of systems have a global efficiency of between 8 and 11%. In the situation that electricity prices
continue to be invariable (low), the solar refrigeration systems will have to reduce their costs by a factor of
3 to 5 times the actual costs in order to become competitive with the traditional vapour compression
systems, The experts expected that all the technologies described would achieve the state of commercial
introduction by 1995. Only ammonia /water absorption systems with flat plate collectors could achieve it by
the year 2000. It was considered difficult to predict the date when these solar technologies reach maturity.
The problem is not only technical but it incorporates economical, social and environmental aspects.