Economic Evaluation of Solar Cooling Schemes

This paper provides an economic evaluation and comparison of ejector, absorption and vapor compression systems driven either partly or fully by solar energy. Life cycle costing has been used to assess the relative economic ranks of eight solar cooling schemes. It has been shown that the capital cost of solar collectors is the dominant capital cost item in the total inventory of solar cooling plant, which has a strong influence on the system life cycle costs. Lower collector costs are therefore critical in establishing economically viable solar cooling systems. Primary energy analysis has been carried out and the running costs of chillers were determined for the maximum range of thermal and electric solar fractions and a number of annual equivalent full load hours of operation. The results indicate that two low temperature flat-plate collector assisted single-effect absorption chillers compete favorably with a PV assisted centrifugal mechanical compression chiller across the maximum range of thermal and electrical solar fractions. Low temperature options for solar cooling have been shown to be more economical than their high temperature counterparts. At current collector prices, solar cooling systems are still not cost effective compared with conventional centrifugal cooling systems, however, it is shown that at a collector cost of £57/m2 for thermal energy and £1.8/Wp for electrical energy, single-effect solar absorption and PV-centrifugal compression could become cost effective within an annual EFLH of 5840 hours. As such, the paper presents technical guidance on the procurement and operation of solar cooling plant. The novel energy and cost calculation methodology developed here can be applied globally to a wide range of solar collectors, chillers, heat rejection and ancillary subsystems.