Scanning Kelvin probe microscopy (SKPM) measurements reveal a higher positive surface potential at the grain boundaries (GBs) as compared to the grain while conductive atomic force microscopy (C-AFM) measurements show higher current flow in the vicinity of the GBs of Cu2ZnSnS4 (CZTS) and Cu2ZnSn(S, Se)(4) (CZTSSe). These results demonstrate the enhanced minority carrier collection taking place at the GBs of CZTS and CZTSSe.