We report herein large area (> 10 cm(2)), interconnected organic solar cell modules both on glass substrates as well as on flexible ultra-high barrier foils, reaching 1.5% and 0.5% overall power conversion efficiency under AM 1.5 conditions. Series connection is described, as these modules consist of tip to three cells. Using our flexible barrier material, a shelf lifetime of polythiophene-based solar cells of 6000h could be realized. Furthermore, we compare the photovoltaic performance of efficient conjugated polymer: fullerene solar cell modules with established technologies. Under typical indoor-office lighting, our modules are competitive with these systems. (c) 2006 Elsevier B.V. All rights reserved.