Smart Grid and Renewable Energy, 2017, 8, 212-219 http://www.scirp.org/journal/sgre ISSN Online: 2151-4844 ISSN Print: 2151-481X DOI: 10.4236/sgre.2017.86014 June 30, 2017 Degradation Analysis of a Rooftop Solar Photovoltaic System—A Case Study Sheeraz Kirmani 1 , Mohammad Kalimullah 2 Department of Electrical Engineering, Jamia Millia Islamia (A Central University), New Delhi, India Abstract The solar photovoltaic (PV) market has grown very rapidly throughout the past 15 years and is quickly becoming an international, non-subsidized mar- ket with increased demand for performance certainty. An increasing number of studies analyze long-term monitoring data to determine degradation rates, or “rates of change” (RoCs). Analyses of long-term monitoring data give in- sight in the performance of PV power plants over time, but are found to be sensitive to uncertainties, especially those related to irradiance measurements using silicon reference cells. The case study analysis shows, however, that the RoCs are much lower if reference cells are adjusted for soiling, drifting and sensor replacements or if satellite irradiance data is used. This indicates that the impact of biased irradiance data should not be underestimated. It was also found, that the distribution of RoCs is strongly influenced by the age and size of the selected systems, underlining the importance of system selection. The case study analysis indicates that crystalline silicon PV systems operating for 8+ years are expected to show a “rate of change” of -0.5% per year or fewer. In this paper the 15-minute data has been collected from a solar photovoltaic generating station installed on the roof of engineering college building and ef- ficiency/degradation of solar panels have been analyzed and reported. Keywords Degradation, Drift, Irradiance, Rates of Change, Silicon Reference Cell 1. Introduction The conversion of sunlight to electricity takes place within the solar cells. Crys- talline silicon semiconductor is manufactured by a silicon purification process, ingot fabrication, wafer slicing, etching and doping which finally forms a PNP 1 Assistant Professor. 2 Research Scholar. How to cite this paper: Kirmani, S. and Kalimullah, M. (2017) Degradation Analy- sis of a Rooftop Solar Photovoltaic Sys- tem—A Case Study. Smart Grid and Re- newable Energy, 8, 212-219. https://doi.org/10.4236/sgre.2017.86014 Received: April 7, 2017 Accepted: June 27, 2017 Published: June 30, 2017 Copyright © 2017 by authors and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY 4.0). http://creativecommons.org/licenses/by/4.0/ Open Access