Sreekumar [84]
conducted an economical analysis and compared the costs of
solar-dried and branded products dried using other drying meth
ods, such as dryers that used fossil fuels. Three methods were used
for the economical comparison of the product costs. In the first
method, the cost per unit weight of drying a product using solar
dryer was compared with that of the same product that used an
electrical means of drying. The cost of drying per unit weight was
calculated by dividing the total annual cost by the amount of
product dried in a year. One disadvantage of this method was that
the cost of drying did not fully capture the economics of the solar
dryer because of the cost variation during the entire life of the
dryer, namely, 20 years. Whereas solar dryers use electricity for
blowers and axial fans,conventional dryers need more energy to
produce hot air. Thus,instead of considering a certain year to
assess the economic benefits of the solar dryer,we must determine
the savings over the entire life of the dryers. The second
method employed this concept. Initially,the savings on drying per
day of the solar dryer in the base year is determined. Then, the
present worth of the annual savings over the life of the system is
obtained [87]. Persuading people to use this dryer depends on the
payback period. The third method, namely, payback period ,
requires the time to recover the initial in vestment.