A flat-plate static-concentrator photovoltaic module is under development. This concentrator module consists of a 3.2 mm-thick cover glass, monofacial or bifacial solar cells 10-25 mm wide, and a reflector sheet with submillimeter V-grooves. The distribution of optical collection efficiency at the zenith and azimuth angles of incident light was calculated using a ray-tracing program. It indicated that about 90% of the annual irradiation could be collected by a mono-facial-cell-type module with concentration ratio of 1.5 and by bifacial-cell-type module with concentration ratio of 2.0. Experiments showed that 38 x 35 cm(2) concentrator module with monofacial cells yielded maximum power equivalent to a conventional flat-plate module of the same size. (C) 2001 Elsevier Science B.V. All rights reserved.