Decarbonizing residential water heaters through solar energy: Long-term energy and emission impacts in Azerbaijan

The decarbonization of residential domestic hot water systems is a key component of reducing greenhouse gas emissions in fossil-fuel-dependent energy systems. Although Azerbaijan possesses considerable solar potential, the long-term environmental benefits of solar water heater (SWH) deployment under local climatic conditions remain insufficiently quantified. This study evaluates the technical performance and decarbonization impact of an evacuated tube SWH system for a representative residential building in the Aghdam district using dynamic simulation modeling. The results indicate that the proposed system achieves a solar fraction of 0.47 and reduces annual auxiliary energy consumption by 2863 kWh. Over an assumed 20-year operational lifetime, cumulative energy savings reach approximately 57 MWh. Depending on the displaced energy carrier, total lifetime CO₂ emission reductions range between approximately 11.6 and 25.2 tons. These findings demonstrate that solar water heating provides a technically feasible and environmentally effective pathway for residential decarbonization, offering measurable long-term emission mitigation potential in support of Azerbaijan’s renewable energy transition and postconflict reconstruction strategies.