Nigerian Journal of Solar Energy 23 (2012) 70-76 Corresponding Author: O. A. Babatunde Email: boribabatunde@gmail.com EFFICIENCY MEASUREMENT OF A PHOTOVOLTAIC SYSTEM O. A. BABATUNDE, L. O. EHWERHEMUEPHA, C. D. NNA and O. ADEGBENRO National Centre for Energy Efficiency and Conservation (The Energy Commission of Nigeria) Faculty of Engineering, University of Lagos Lagos, Nigeria ABSTRACT Renewable energy has become an integral part of the energy mix in Nigeria due to the continued depletion of fossil fuel reserves and the environmental pollution associated with its use. As a result, the use of solar photovoltaic technology is no longer uncommon. Photovoltaic systems of various technologies are found to be imported from different countries and are being used locally with little or no information of their appraisal and field performance. This research determines the in situ practical efficiency of a photovoltaic system. The illuminance of the sun on the solar panels, output current and voltage of the panels are measured at regular time intervals of the day over a month period. The ultimate goal of the research is to develop standards by which the quality of photovoltaic systems can be measured. Keywords: Photovoltaic system, Efficiency, Solar panel, Illuminance