Global Challenges of Current Building-Integrated Solar Water Heating Technologies and Its Prospects: A Comprehensive Review

Abstract

Among the renewable energy resources, solar thermal is one of the technologies that significantly contribute to energy supply and reduce global greenhouse gas (GHG) emissions. Solar water heating (SWH) contributes a large proportion of the global solar thermal capacity, with 63% installation for domestic hot water (DHW) systems, 28% for large DHW systems, and the remaining 9% for other applications such as swimming pools heating, solar district heating, and space heating. Still, now, there are many challenges and limitations of those SWH technologies. The present work reviews the current challenges faced in the domestic SWH industry globally. The integration of thermal energy storage (TES) systems for better collector’s radiation absorption and overall performance are also highlighted. Many countries worldwide seem to face similar challenges within the SWH technologies and industry. It is proven that these challenges and limitations can hinder the global capacity of solar thermal utilization.

Review on the Progress of Solar Water Heaters and Their Future Perspectives

“…The remaining 9% of SWH systems are dedicated to fulfilling the heating needs of swimming pools, solar districts, and space heating. [ 44 ] The functioning of SWH systems is based on the principle of solar heat absorption through a collector. The collector, typically mounted on rooftops or other suitable locations, absorbs solar radiation and transfers the heat to a circulating fluid, usually water.…”

“…Active SWH requires additional devices, such as pumps resulting in higher production costs. [ 44 ] A mechanical pump is required to circulate the transition fluid in a heat exchanger copper coil mounted in a separate water tank for the active system. This is to increase the thermal efficiency of the SWH while requiring other additional equipment.…”

“…Solar radiation variability and site‐specific factors present significant hurdles to successfully implementing SWH systems. [ 44 ] Solar energy, for instance, varies across locations, impacting the system's ability to conserve hot water. High‐altitude areas with frequent cloud cover pose a particular challenge, leading to a reduced primary energy source.…”

“…In fact, there are still technical obstacles and unanswered questions that require further investigation. [42,44,48,49] This review aims to address these issues and provide insights into the current state of SWH technology, including its collector efficiency enhancement, evaluating its challenges and constraints, and identifying opportunities for efficiency improvement and innovation. Therefore, this review article has three main goals.…”

PCM-based domestic solar water heating in Malaysia: Setbacks and countermeasures

“…Applications for heating water, steam, or spaces utilize the heat carried by the working fluids. Hence, it can be stated that SWH technologies have fulfilled some of the Sustainable Development Goals (SDGs), including SDG 7 (i.e., solar water heaters are compatible with urban and rural areas), SDG 11 (i.e., solar collectors are implemented in existing commercial and residential buildings), and SDG 13 (i.e., SWH technologies contribute to the carbon emission reduction) [1]. Malaysia's electricity consumption in residential and commercial sectors has been increasing since 1978.…”