Feasibility of Cooling a Photovoltaic Fresnel System by Water Spraying

Abstract

The Fresnel system can achieve high electrical energy yield compared to the traditional photovoltaic (PV) panel techniques due to the concentration of solar energy. However, this huge energy might cause overheating of the PV panel. The objective of this research is to mathematically model a linear Fresnel system that is cooled by either spraying the PV panel by tap water or chilled water, in order to determine the maximum possible concentration ratio, which is called the critical concentration ratio. Then, the model is further used to study the effect of cooling on the PV panel in real life operating conditions in two cities; the first one is a hot city which is Cairo, Egypt, and the other one is a cold city which is Stuttgart, Germany. The objective is to find out the Critical concentration ratio (Cr) at which the maximum energy output from the system can occur as a function of the operating conditions. The results of this study show that cooling of the PV panels using chilled water system is not feasible. Therefore, in order to improve the feasibility, a low energy cooling system should be adopted. Such system may include spraying tap water on the PV panels, recollecting the water and cooling it naturally underground and finally spraying it again on the panels. The maximum output energy has increased by approximately 75%, compared to the no-cooling case, due to water spraying, which indicates the feasibility of water spraying in Fresnel systems.