Improvement of thermal performance of an indirect flat plate solar collector in solar water heater applications
DOI:
https://doi.org/10.15587/1729-4061.2026.358842Keywords:
solar collector, water tank, indirect system, power plant, water heaterAbstract
The object in this study is the process of heat transfer, energy conversion, and heat distribution through solar collectors in indirect systems. The problem to be solved is to develop sustainable alternatives powered by renewable energy sources, such as solar energy
This study is focused on the research of a solar water heater (SWH) system incorporating flat plate solar collectors (FPSC). The system enhances the thermal performance of the FPSC through an indirect, closed-loop configuration. Water from the hot water tank (HWT) is circulated through the FPSC copper pipes by a pump powered by a Solar Power Plant, ensuring continuous heat transfer and efficient thermal performance. The system operates at a flow rate of 0.116 kg/s. A K-type thermocouple connected to a data logger records the water temperatures at the HWT’s inlet and outlet every 30 seconds. In addition to the system, the features of this study also focuses on phase change material (PCM) which uses mannitol material as thermal energy storage (TES) which will be used during cloudy or rainy weather. All equipment such as plunger pumps, heaters for PCM use solar electricity. The feature of this study also uses the Internet of Things (IoT) to find out the temperature in the solar water heater tank. The test results indicate a maximum FPSC thermal efficiency of 72% and a coefficient of performance (COP) of 10 under a pump power of 100 W and an absorbed heat input of 1000 W. The average solar irradiance ranged from 850 to 950 W/m2. These results demonstrate the potential of this technology to efficiently meet domestic hot-water demand and its suitability for deployment in tropical regions.
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Copyright (c) 2026 Mochamad Sugiri, Budhi Muliawan Suyitno, Erlanda Augupta Pane, Gunadi Haryanto, Ismail Ismail

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