Nowadays, there is huge energy demand, and this energy demand is fulfilled by fossil fuels, but these non-renewable resources will create crisis in future especially for developing countries. Hence, the implementation of renewable resources and increasing their dependency is a major concern. In this paper, simulation was done for one of the heat transfer augmentation techniques in the solar water heater that by implementing rectangular fins also without fins and different materials such as copper, stainless steel, and aluminium. The CAD model was created in Solid works, and thermal analysis was done in Autodesk Fusion 360. Finally, the result achieved was that the rectangular-based solar water fin tube had greater heat flow than the without fin solar water tube by 12 °C. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.