We propose a cost-effective, low-temperature antireflective coating for the outer glass substrates of 1.43 m(2) thin-film Si photovoltaic modules using a WO3-TiO2 nanoparticle photocatalyst The coated nanoporous films provide the broadband antireflective effect, which results in the increased initial performances. Notably, the self-cleaning effect due to the photo-induced superhydrophilicity leads to a significantly reduced outdoor-exposed degradation. Therefore, the drastic energy output gain of 4.3% is achieved for a tandem photovoltaic module via a long-term outdoor field test. (C) 2013 Elsevier B.V. All rights reserved.