To answer how surface corrosion affects the heat transfer performance of phase-change immersion cooling solar cells, electrochemical etching was used for substrate surface treatment of simulated dense-array solar cells in this paper. Morphology, roughness, and wettability of treated surfaces were characterized by scanning electron microscope, atomic force microscope, and spreading area, respectively. A self-running cooling system was developed to investigate the effect of surface treatment on self-running characteristics and heat transfer performance under different ethanol inlet temperatures and concentration ratios. The results show that the surface treated for 2hours owns higher wettability because of the honeycomb-like porous structure. Lower ethanol flowing velocity obtained under lower ethanol inlet temperature with treated samples. The maximum declined degree in the wall superheating of 21.1% and the maximum enhancement in the heat transfer coefficient of 33.3% are obtained for sample treated for 2hours because of its higher wettability and porosity structure. The results show that electrochemical etching on substrate surface can improve the phase-change immersion cooling performance of solar cells.