Optimal design and operation of conventional, solar electric, and solar thermal district cooling systems

Abstract

This research investigates the integration of solar energy with traditional cooling technologies using solar electric cooling systems. A holistic optimization process is introduced to enable the cost-effective design of such technology. Two mixed-integer linear programming (MILP) models are developed, one for a baseline conventional cooling system and the other for a solar electric cooling system. The MILP models determine the optimal system design and the hourly optimal quantities of electricity and cold water that should be produced and stored while satisfying the cooling demand. The models are tested and analyzed using real-world data, and multiple sensitivity analyses are conducted. Finally, an economic comparison of solar thermal and solar electric cooling systems against a baseline conventional cooling system is performed to determine the most cost-effective system. The findings indicate that the photovoltaic panels used in solar electric cooling cover 42% of the chiller demand for electricity. Moreover, the solar electric cooling system is found to be the most cost-effective, achieving ~5.5% and 55% cost savings compared with conventional and solar thermal cooling systems, respectively. A sensitivity analysis shows that the efficiency of photovoltaic panels has the greatest impact on the annual cost of solar electric cooling systems—their annual cost only increases by 10% when the price of electricity increases by 20%, making solar electric the most economical system.