The use of solar water heating systems (SWHSs) has grown as an alternative source of energy to heat water. In Kenya, commercial premises are required to install these systems to conserve energy and the environment; however, after the SWHS has been designed and installed according to the relevant standard, post‐installation factors significantly influence its performance. In this study, the impact of user behavior and waiting time for hot water on the performance of SWHS is investigated using experimental tests and analysis. In the operations of SWHS, water that cools off in the piping system during idle time must be flushed before hot water is supplied, and generally, the cold water goes to waste. This wastage increases the water demand, the amount of liquid waste for disposal, the cost of recycling, and the energy demand for pumping the water. The proposed system involves installing instantaneous water heaters controlled by a fuzzy logic controller in an SWHS to heat water during waiting time and reduce energy and water wastage associated with waiting time and user behavior. The study was carried out in 15 hotels in Kenya. It was observed that installing instantaneous water heaters in an SWHS reduces the waiting time for hot water by 96.90%, saving 14.4 liters of cold water while the user behavior losses were reduced resulting in a saving of 54.6 liters of hot water. The energy savings associated with pumping water was 0.025 kWh per hotel room on average. From these savings, the running cost was reduced by 80.6%. With this hybrid system, an additional 0.117 kWh of energy was consumed by the 4.8 kW instantaneous heater to heat water during waiting time. From these findings, it’s feasible to effectively reduce waiting time, reduce water wastage, and mitigate user behavior losses in hotels by incorporating instantaneous water heaters in SWHS.
