The current study experimentally investigates the performance of two identical pairs of photovoltaic (PV) panels., the first being clean and the second being artificially polluted with three different, commonly met in urban and other environments, air pollutants (i.e. red soil, limestone and carbonaceous fly-ash particles). The PV-panels under comparison are both operating under the same environmental conditions, being nearby located and adjusted at the same inclination. The effect of pollution deposition on PVs' power output, energy yield and conversion efficiency is examined, considering also various pollutants' mass depositions on the PV-panels' surfaces. According to the results obtained, a considerable reduction of PVs' energy performance is recorded, depending both on particles' composition and origin and on the total mass accumulated on the PV-panels' surfaces. Based on the results, the highest reduction is caused by the deposition of red soil particles, followed by the deposition of limestone and finally by the carbon-based ash. (C) 2011 Elsevier Ltd. All rights reserved.