The superiority of solar water heating system and its development trend in China
Advantages of solar water heating system
For a long time, people have been aware of the role of solar energy, and have been working hard to study and use solar energy.
In recent decades, under the dual pressure of energy crisis and environmental problems, solar energy has become the focus of people’s attention due to its infinite, clean, universal and other advantages, trying to use it as a substitute for other conventional energy sources. At present, the application of solar energy mainly includes three types of solar thermal utilization, photovoltaic utilization and photochemical utilization. It can also be divided into two different application methods, active application and passive application. The solar hot water system is an active solar light and heat utilization technology, which uses the greenhouse principle to convert solar energy into heat energy, heat cold water, and use it for preparing domestic and industrial hot water or heating. The simplest solar water heating system is the most commonly used small domestic solar water heater, which can only prepare domestic hot water for one household; the large-scale solar water heating system can provide domestic hot water and heating for one household or even the entire residential area.
The “energy crisis” broke out in the world in the 1970s, and there was a climax in the development and utilization of solar energy throughout the world. Since this period, China has also begun large-scale production and application of solar water heaters. After more than 30 years of development, solar water heating systems (heaters) have become the most mature, widely used, and most industrialized technology in solar thermal utilization technologies. A complete industrial chain of solar water heaters has been formed in China. The production technology of various components of the system, such as solar collectors, water storage tanks, pipes and accessories, has matured, and the product quality and performance are constantly improving. According to statistics from the IEA (International Energy Association) as of the end of 2007, China’s annual output of solar water heaters reached 23.4 million m², with a total possession of 108 million m², and the area of solar water heaters per 1,000 people reached 83.1m². Compared with other unconventional energy utilization technologies, the social recognition rate and penetration rate of solar water heating systems (heaters) have reached a certain level.
Solar water heating system has many advantages such as energy saving, environmental protection, economical and practical, and easy to operate. China has a population of 1.3 billion and about 350 million households. If each household supplies 120L of hot water at 60°C per day, 800 billion kilowatt-hours of electricity will be needed throughout the year, and the electricity bill will be about 400 billion yuan. The solar hot water system can provide 80% to 90% of the hot water energy in summer, and basically does not need other energy; the cold water can also be preheated during the transition season and on sunny days in winter, so that the initial water temperature for auxiliary energy heating reaches 30~50°C, thereby reducing the consumption of conventional energy. When using solar energy, it also does not produce waste residue, waste water, exhaust gas and noise pollution, and will not have a negative impact on the environment. In addition, although its initial investment is higher than that of ordinary electric water heaters and gas water heaters, the payback period is short and the rate of return is high. Compared with the use of electric water heaters, larger solar hot water systems have a static recovery period of about 4 to 7 years, and their service life can reach more than 15 years. The initial investment can be fully recovered within the service cycle and conventional energy costs can be saved.
With the reduction of conventional energy reserves, rising prices, and the emergence of environmental problems, these advantages of solar water heating systems will become increasingly apparent, and they are worthy of extensive promotion and application.
The development trend of solar water heating system in China
China’s solar water heating system has been widely used in rural areas since the 1970s. It is mainly used in rural residential houses and low-rise and multi-storey residential buildings in cities and towns. The application in high-rise residential buildings is still rare. However, it is worth noting that China is currently in the process of rapid urbanization, and the increasing urban population is putting tremendous pressure on urban construction. With the decrease of urban construction land and the increase of prices, high-rise residential buildings with high plot ratio and high green space ratio have become the mainstream of residential forms. In addition to the promotion of the market mechanism, government departments have also issued relevant opinions and policies to clarify the development ideas of high-rise housing, relax the floor area ratio and building height, and encourage the construction of small high-rise and high-rise housing in urban planning areas to effectively improve the efficiency of land use. At the same time, buyers’ understanding and recognition of high-rise residential buildings is also increasing.
It can be seen that high-rise residential buildings will definitely become the main body of urban residences in the future, and if solar water heating systems need to be further promoted and become basic living facilities for urban residents, what is urgently needed and must be solved is the application of high-rise residential buildings.