Thermal energy storage applications in solar water heaters: An updated review

Fossil fuel usage for heating applications must be reduced considering the issues related to the environment and the restriction of their resources. In this regard, attention is devoted to renewable energy sources to supply the energy requirements of different sectors. In the building sector, solar energy is harnessed for heating and cooling. Solar energy is applicable both directly and indirectly for heating using different technologies. The intermittent nature of solar energy obliges the use of storage units to make the solar systems applicable at night hours or during periods the low solar intensity. Various thermal energy storage materials have been utilized in different kinds of solar heaters to stabilize their performance, improve their reliability, and avoid issues related to variations in solar radiation. In this article, studies on the usage of thermal energy storage units in solar water heaters are reviewed and their key results are reflected. As one of the main conclusions of the reviewed works, it can be denoted that several factors such as the operation condition and characteristics of the storage unit are effective on the function of the systems combined with the thermal storage component. Aside from an increment in the operating hours of solar heaters, usage of storage units can boost both energy and exergy efficiencies. Furthermore, the study denotes that the power saving rate is influenced by the abundance of solar energy resources. In addition, it could be denoted that the performance of the systems is improvable by employing some ideas, such as the application of nanotechnology in storage materials.

Automated summary

In order to reduce the usage of fossil fuels for heating applications, attention is given to renewable energy sources to meet energy requirements in various sectors. Solar energy is harnessed in the building sector for heating and cooling, directly and indirectly using different technologies. The intermittent nature of solar energy necessitates the use of storage units, and various thermal energy storage materials have been used in solar water heaters to improve performance and overcome issues related to variations in solar radiation. Factors such as the operation condition and characteristics of the storage unit affect the function of the systems, and the use of storage units can boost energy and exergy efficiencies while the power saving rate is influenced by the abundance of solar energy resources. Additionally, employing ideas such as nanotechnology in storage materials can further improve system performance.