We report efficient flexible polymer solar cells based on ITO and ITO-free semi-transparent electrodes consisting of either a highly conductive PEDOT:PSS formulation (PH1000) or a combination of printed silver grids and PH1000. As active layer material a polymer:fullerene bulk heterojunction based on PCDTBT:PC70BM (Poly[[9-(1-octylnonyl)-9H-carbazole-2,7-diyl]-2,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl]:phenyl-C71-butyric acid methyl ester) was used. We demonstrate that the printed silver grid in combination with PH1000 leads to comparative device performances as ITO-coated PET substrates and has the potential for more. (C) 2014 Elsevier B.V. All rights reserved.