Metallization of silicon solar cells using electroplating is of interest recently as a cheaper replacement of silver screen printing. Light assisted electroplating of Nickel-Cobalt (NiCo) alloys were studied on crystalline silicon (Si) solar cells in this paper. The effect of illumination was investigated in conjunction with the light absorption properties of the plating solution, emission spectrum of the light source as well as the plating current. A solution dependent threshold light intensity was observed, beyond which the solar cells were under reverse bias during electroplating. The detailed compositional depth profiles of the silicide layer were studied along the silicidation reaction using microscopic energy dispersive X-ray spectrum (EDS). A significant improvement in the performance degradation at high temperature thermal stress was observed for solar cells metalized with the ternary silicide.