A new photovoltaic/thermal heat pump (PV/T-HP) system having a modified collector/evaporator (C/E) has been developed and numerically studied. Multi-port flat extruded aluminum tubes were used in the modified C/E, as compared to round copper tubes used in a conventional C/E. Simulation results suggested that a better operating performance can be achieved for a PV/T-HP system having such a modified C/E. In addition, using the meteorological data in both Nanjing and Hong Kong, China, the simulation results showed that this new PV/T-HP system could efficiently generate electricity and thermal energy simultaneously in both cities all-year-round. Furthermore, improved operation by using variable speed compressor has been designed and discussed. (C) 2009 Elsevier Ltd. All rights reserved.