This paper reports on the investigation of Cu(In,Ga)Se-2 thin-film solar cells for application under low irradiance conditions with irradiance E < 1 mW/cm(2). Under such conditions, a parallel resistance R-p > 10 kOmega cm(2) of the solar cells is required. We find that Cu(In,Ga)Se-2 absorber material with a low Cu content of 18 at.% provides R-p > 100 kOmega cm(2) and enables solar cells to exhibit a power conversion efficiency of 6% under an irradiance E=0.1 mW/cm(2). Under such conditions, standard Cu(In,Ga)Se. absorber material with a Cu content of 21.5 at.% is not a suitable photovoltaic absorber material because the RP of the corresponding solar cells is too low. Further investigations of different solar cells with a variety of Cu contents in the absorber material reveal that the shunt resistance of the solar cells is proportional to the bulk resistivity of the corresponding Cu(In,Ga)Se, absorber materials. This observation leads us to the proposition that the parallel resistance in Cu(In,Ga)Se2 solar cells originates from highly localised shunt regions in the absorber material. (C) 2003 Elsevier B.V. All rights reserved.