Thermal Energy Storage Enhancement in Solar Water Heating Systems Using Phase Change Materials

Abstract

In this work, renewable energy sources—particularly solar energy—were utilised as sustainable alternatives to fossil fuels. The study experimentally investigated a solar thermal water heating system and explored methods to prolong heat availability during periods without solar radiation, such as at night or under intermittent sunlight. To achieve this, paraffin was employed as a Phase Change Material (PCM) to enhance thermal storage performance. The integration of paraffin significantly improved thermal stability and energy retention, with water temperature reaching approximately 65 °C without PCM and remaining around 60 °C with PCM, maintaining heat for up to four additional hours after sunset. Furthermore, increasing the paraffin mass from 0.5 kg to 1 kg enhanced latent heat storage and extended temperature stability, demonstrating greater system efficiency and reduced heat loss., then returns to its initial state during the discharge period to heat water efficiently and economically.