Solar water heating: From theory, application, marketing and research

The aim of the paper is to provide a comprehensive critical review towards the solar water heating (SWH) technology in terms of its theory, application, market potential and research questions. The theoretical issues relating to the solar water heating technology were illustrated in terms of the working principle, classification and associated mathematical expressions. The existing SWH production and engineering application were introduced and its future market potential was also predicted. Furthermore, research questions relating to the SWH were analysed involving (1) whole structure and individual components layout, sizing and optimisation; (2) thermal performance simulation and prediction; (3) laboratory based measurement compared against the modelling prediction; (4) dynamic performance evaluation through real time and on-site measurement; (5) energy saving, economic and environmental performance assessment, and social acceptance analyses; and (6) dissemination, marketing and exploitation strategies. Finally, the opportunities for the further works on the SWH were identified. This study will help understand the current status of the economic and technical developments, identify the barriers remaining to the existing solar water heating systems, develop the potential research areas to improve the performance of the systems, establish the associated strategic plans related to the design and installation of the system and promote the solar thermal global market. The study will contribute to achieving the China and international targets for energy saving, renewable energy utilisation, as well as carbon emission reduction in building sector.