Evaluation of rooftop photovoltaic electricity generation systems for establishing a green campus

Abstract

This study employs geographic information systems (GIS) and the system advisor model (SAM) to assess the potential for rooftop photovoltaic (PV) generation in establishing a green campus. A university campus was taken as the subject area for the research. First, shadow analyses were conducted using a digital elevation model (0.1 m grid spacing) of the study area and the heights of buildings therein. GIS-based spatial analysis tools were used to analyze shadows and their overall patterns. Local conditions at winter solstice were used as a basis for conservative shadow analysis, giving an estimate that 1800 PV modules could be installed on the rooftops of 19 buildings. The SAM was used to conduct energy simulations, based on weather data from the Korea Solar Energy Society. The results indicated that the PV system could produce an estimated 300,269 kWh of energy annually on the campus. Net present value (accounting for inflation and the 20-year operational lifetime of the PV system) showed that economic gain was unlikely at present electricity costs and inflation rates. However, economic gain varied considerably according to the orientation of the PV modules. Southward orientation was expected to give economic returns at an electricity cost of 161 KRW/kWh. Those sites where southward orientation of the solar panels was not possible showed reduced potential for economic return.