The authors have developed experimental thermal-photovoltaic (PV) hybrid exterior wallboards that incorporate of PV cells. The clapboard-shaped hybrid wallboards permit modular assembly that can be more easily adapted for building applications than previous PV systems. Solar heat is collected in the form of heated air circulating in the air gap between the hybrid wallboard and the thermal insulation of the exterior walls. This paper presents an evaluation of both the electrical power generating ability and the solar heat collection capacity during winter of six variations of the experimental thermal-PV hybrid wallboard. In addition, exergy analyses were conducted. (C) 2002 Elsevier Science B.V. All rights reserved.