ABSTRACT
Renewable energy systems (RESs), which include but are not limited to wind power, hydropower, solar energy, and geothermal energy, have become vital parts of future energy use resources because fossil fuels are declining but demands for energy keep growing. Solar energy has become a fast-growing energy source in the last few years. Compared to other renewable sources of energy, solar energy has the following advantages: it is inexhaustible, it can drastically reduce energyrelated greenhouse gases to help limit climate change, it is relatively well spread over the globe (Philibert 2011), and it is not subject to geological, climatologic, and morphologic conditions. The largest demands of solar energy are coming from urban areas because more than half of the world’s population lives in the urban environment (Weng 2015). Solar energy absorption equipment can be groundmounted arrays close to where the energy is used or directly mounted on rooftops (SEIA 2014). There are three primary technologies by which solar energy is commonly harnessed: photovoltaic (PV), concentrating solar power, and heating and cooling systems (SEIA 2014). In the dense urban areas, the PV equipment are encouraged to be mounted on the rooftops. First, it is not realistic to allocate a large land to ground-mount them. Moreover, buildings are the largest energy consumers in the urban area today (Philibert 2011), and the PV modules mounted on the roofs can directly transfer the solar energy absorbed from sunlight into electricity and sold to the electric companies.
