Performance Analysis of a Facade-Integrated Photovoltaic Powered Cooling System

Due to recent changing climate conditions and glazing of building facades, a rapid increase in the requirement of cooling systems can be observed. Still the main energy source for cooling are fossil fuels. In this article we report on a fully integrated approach of running a heat pump for actively cooling a test room by electric energy, generated by facade integrated photovoltaic modules, the “COOLSKIN” system. Photovoltaic facades are emission free in the operation phase, efficiently utilize otherwise unused surfaces, and portray a favorable method in terms of construction physics and the architectural design of buildings. Compared to existing systems, COOLSKIN is an entirely autonomous system where every component is located inside the facade structure which introduces a high level of plug and play character. In this article the analysis of the electric performance of the COOLSKIN system with respect to its operation under different environmental conditions is presented. The over all system efficiency was determined with 73.9%, compared to a simulated efficiency (PV*SOL) of 68.8%, and to the theoretically expected value of 85%. The system behavior is evaluated depending on photovoltaic output and the cooling demand. The analysis shows that a considerable amount of cooling demand could be decentrally fulfilled with photovoltaic energy, but environmental conditions as well as system layout have a considerable impact on system performance.