This study aimed to evaluate the thermal performance of a solar water heater system with the trickle-flow method using a combination of polymethyl methacrylate (PMMA) as the cover and galvalume as an absorber plate. The flat-plate-type collector was designed with a closed flow system in which water trickled directly onto the surface of the absorber and was recirculated through the storage tank. The experiment was conducted in a tropical area in Indonesia with four variations in the collector orientation

i.e. south

north

east

and east

tilted at 30°. Furthermore

the parameters measured included the solar-radiation intensity

wind speed

and water temperature at the inlet

outlet

and in the tank. The collector efficiency was also calculated based on the useful thermal energy absorbed by the plate

while the system efficiency was reviewed through the heat energy transferred to the water. The results showed that the collector direction had a significant effect on system performance. The collector with the eastward orientation produced the highest total efficiency of 32.7%

with a maximum water temperature of 45.8°C. These results indicate that an eastward orientation is more effective for a trickle-flow-based solar water heater system in tropical areas. Additionally

the PMMA–galvalume material shows potential as a lightweight and efficient alternative for household applications.