An assessment of solar rooftop potential on Lampang Rajabhat University's buildings based on digital surface model (DSM) from unmanned aerial vehice (UAV)
Abstract:
This research aimed to assess the solar rooftop potential using a digital surface model (DSM) generated from an unmanned aerial vehicle (UAV) and to analyze the feasibility of investing in rooftop photovoltaic systems for Lampang Rajabhat University's buildings. The research methodology involved conducting a UAV survey and utilizing automated software to process UAV images, creating an Orthophoto and a digital surface model (DSM) with a resolution of 10 cm/pixel to analyze point solar radiation in ArcGIS Desktop. The derived solar radiation values were then employed in evaluating the viability of investing in rooftop photovoltaic (PV) systems, considering factors like Net Present Value (NPV), Internal Rate of Return (IRR), and Payback Period (PB) through project analysis and evaluation. According to the analysis, the solar radiation value on the building roof in 2020 was 4.28 kWh/m2 per day, 130.69 kWh/m2 per month, or 1,415.8 kWh/m2 per year. The solar radiation was lowest between December and January, while May-July showed higher values due to the sun's changing position in the sky throughout the year. South-oriented pitched roofs had high solar radiation, nevertheless slopes steeper than 40° reduced the radiation. Flat roofs with solar panels oriented south and inclined at around 15° were found to be effective. The study revealed 23 buildings with solar rooftop potential and 4,106 solar panels covering 8.29 percent of the roof area and generating a total capacity of at least 1,300 kW. When the PV estimated value was compared to the actual value, a 0.19% difference was found. After adjusting the PV estimated value in PV-potential areas, the solar energy potential was determined to be 127,003.68 kWh per month or 1,524,044.15 kWh per year. This potential could result in a 42.28% reduction in the university's electricity costs. The feasibility results for investing in a rooftop photovoltaic system showed positive Net Present Values (NPVs) during the project's 25-year life. The Internal Rate of Return (IRR) exceeded the project's discount rate, the weighted average cost of capital (WACC). Furthermore, the payback period was 9 years and 6 months, which was much shorter than the project's full period of time. As a result, the findings support the project's financial viability and its potential for reducing greenhouse gas emissions by 791.44 tCO2eq per year.