Fully solution-processed Al-doped ZnO/silver nanowire (AgNW)/Al-doped ZnO/ZnO multi-stacked composite electrodes are introduced as a transparent, conductive window layer for thin-film solar cells. Unlike conventional sol-gel synthetic pathways, a newly developed combustion reaction-based sol-gel chemical approach allows dense and uniform composite electrodes at temperatures as low as 200 degrees C. The resulting composite layer exhibits high transmittance (93.4% at 550 nm) and low sheet resistance (11.3 sq(-1)), which are far superior to those of other solution-processed transparent electrodes and are comparable to their sputtered counterparts. Conductive atomic force microscopy reveals that the multi-stacked metal-oxide layers embedded with the AgNWs enhance the photocarrier collection efficiency by broadening the lateral conduction range. This as-developed composite electrode is successfully applied in Cu(In1-x,Ga-x)S-2 (CIGS) thin-film solar cells and exhibits a power conversion efficiency of 11.03%. The fully solution-processed indium-free composite films demonstrate not only good performance as transparent electrodes but also the potential for applications in various optoelectronic and photovoltaic devices as a cost-effective and sustainable alternative electrode.