Moreover, the solar still with 3 wt% CuO nanoparticles blended with PCM demonstrated a thermal efficiency of 74.23% and an exergy efficiency of 9.75%. The production cost of distillate for all four stills remained at $0.03 per kg. These findings highlight the effectiveness of the proposed copper plate attached solar still with 3 wt% CuO nanoparticles blended with PCM as a viable method for producing potable water.