Solar still is considered an ideal sustainable solution to address potable water scarcity. It offers low-cost, simple technology with broader application and adaptability but is characterised by low productivity. This problem can be overcome by employing latent heat storage (LHS) materials. But the inherent low thermal conductivity of LHS materials results in a considerable amount of time being consumed during the charging and discharging cycles. Two modified solar stills were developed and tested to address the issue and enhance the productivity of the solar stills used in this work. One with Multi-Walled Carbon Nano Tubes (MWCNT) enhanced Paraffin wax (nPCM), encapsulated in three sandblasted copper cylinders, and the other with composite nPCM, where the open-cell copper metal foam (Cu metal foam) was embedded in nPCM and encapsulated in three sandblasted copper cylinders. The experiment was conducted simultaneously across all developed stills and the results showed that the freshwater productivity of the still with composite nPCM exceeded that of the conventional still by 52.4% and that of the still with nPCM by 6.5%. The results also showed the incorporation of PCM, MWCNT and Cu metal foam in a copper cylinder thermal energy storage system enhancing the exergy efficiency of the still with composite nPCM by 64.2% and 9.3% compared with a conventional still and still with nPCM respectively. In addition to the above results, the energy savings and carbon credit potential of composite nPCM still obtained were higher than those of nPCM integrated solar still by 6.7% and 6.6% and conventional still by 52.8% and 52.9% respectively.