Solar energy systems used only for cooling purposes, are not
economically viable and the capital cost are very high. The initial
cost of solar collectors accounts for 60–70% of the total invest of
solar cooling systems. Consequently, solar cooling systems must be
implemented along with hot-water supply. For example, for the
solar-powered integrated energy system in the green building of
Shanghai Research Institute of Building Science, the pay back
period is about 2–3 years if hot water is utilized for bathing or
showering, however, the pay back period could be 7–8 years if the
hot water is only used for space heating and cooling for the
building.