Experimental Design and Fabrication of a Solar Water Heater Incorporating a Thermal Storage Device for Domestic Applications

A solar water heating system utilizes thermal energy derived from solar radiation or ambient environmental heat to elevate water temperature. However, the inherent intermittency of solar irradiance presents a critical limitation, resulting in fluctuating hot water availability. To address this issue, the present study proposes an experimental prototype of a solar water heating system integrated with a thermal energy storage (TES) unit, designed to ensure a continuous hot water supply during periods of low or absent solar insolation. The system comprises a cylindrical storage tank, copper tubing for heat exchange, an aluminum absorber plate housed within a rectangular collector box with a transparent glass cover, a solar circulation pump, and a thermosyphon mechanism. A hybrid heat transfer strategy, combining natural convection and forced circulation, was employed to optimize thermal efficiency. Performance testing was conducted over four consecutive days in July, under predominantly overcast and rainy conditions, between 09:00 and 16:00 daily. With an initial inlet water temperature of 25 °C, the system achieved a peak temperature increase of 15 °C, corresponding to a net thermal energy gain of approximately 1386 kJ. Results indicate that the TES unit effectively retained absorbed thermal energy and released it during non-solar periods, thereby validating its performance. Furthermore, the use of locally available materials supports the feasibility of constructing low-cost, efficient TES-integrated solar heating systems. These findings contribute to the development of more reliable and sustainable solar water heating technologies for diverse climatic conditions.