A novel non-imaging asymmetric compound parabolic photovoltaic concentrator (ACPPVC) has been designed, constructed and experimentally characterised at the University of Ulster, Northern Ireland (54degrees36'N, 5degrees37'W). Different numbers of PV strings connected in series were experimentally characterised under outdoor conditions both with and without concentrators. Transient I-V curves for each set of parameter data points were determined and the maximum power generation, fill factor and efficiency of the system calculated for each individual I-V curve. Experiments showed that the use of an ACPPVC increased the maximum power point by 62% (i.e. the power by a factor of 1.62) when compared to a similar non-concentrating PV panel. (C) 2004 Elsevier Ltd. All rights reserved.