Application status of solar water heating system in China

Through the comparison of the above contents, it can be seen that the solar water heating system technology in other countries is more mature than China in terms of products, technology, and use. While China has an absolute advantage in terms of usage, solar water heating systems also have their own characteristics in development and application. At present, the characteristics of China’s solar hot water system application can be summarized as follows:

1. Diverse systems

China has a large geographical span, and the climate conditions and economic levels vary greatly from place to place. In addition to seasonal heat storage systems and one-week heat storage systems, various systems commonly used in the world are used in China, but are mainly distributed, natural circulation, and compact solar water heating systems with direct heat exchange.

2. Mainly vacuum tube collectors

Solar collectors in other countries are dominated by flat-plate solar collectors, while in China, they are dominated by evacuated tube types. In combination with buildings, flat-plate collectors are considered to be easier to integrate with buildings, and they have been used quite maturely in some countries. Due to the influence of production cost, product quality, and publicity in China, evacuated tube collectors are the mainstay, which is unique in combination with buildings.

3. Urgent demand for high-rise residential applications

Unlike foreign residential buildings, which are mostly villas, townhouses and multi-storey apartments, while China is dominated by multi-storey, small high-rise and high-rise residential buildings, it is necessary to solve the problem of combining high-rise residential buildings with solar water heating systems. Solar water heating systems and design methods in other countries are not completely applicable to China, and relevant problems must be explored and solved by themselves.

4. Lack of specific encouragement policies and out of touch with the construction industry

The government has issued relevant documents to encourage the application of solar water heating systems, but there is still a lack of specific preferential policies, and real estate developers lack enthusiasm for this new technology. The design of the solar water heating system is not included in the architectural design, and the integration effect cannot be achieved only by relying on the production enterprise for system design and installation.

Problems in the application of solar water heating system in high-rise residential buildings

Through the survey of households and the summary of experience in actual projects, the current combination of solar water heating systems and high-rise residential buildings mainly has the following two problems:

1. The problem of the combination of solar water heating system and the appearance of high-rise residential buildings

(1) The roof area of high-rise residential buildings is limited. When the number of floors is large, the installation of water heaters for all residents cannot be satisfied. The collectors are installed on the facade. According to the current solar spacing of the building, the collectors of low-rise residents cannot receive sufficient sunshine, which seriously affects the efficiency of the system.

(2) At the beginning of the building design, the installation location of the solar collector was not considered, and the image of the collector and the building was not coordinated, which affected the aesthetics of the building.

(3) Unreasonable design and irregular installation of the solar hot water system during the installation of the solar hot water system caused damage to the building structure and waterproof and thermal insulation structure, leading to problems such as rain leakage and falling from high altitude.

2. The problem of the combination of solar hot water system and high-rise residential indoor water system

(1) When using compact solar water heaters in high-rise residential buildings, the fully evacuated glass tube cannot bear pressure. If the water heater is arranged on the roof, there will be a big difference between the hot water pressure of the residents on the top floor and the water supply pressure of the tap water, and users cannot adjust the water temperature freely, which seriously affects normal use.

(2) The solar water heater is installed on the roof, and the pipeline reaches the household water point too long, resulting in serious heat damage to the pipeline and more ineffective cold water. Residents on the lower floors need to drain a lot of cold water to use the hot water.

Realize the large-scale application of solar water heating system in urban high-rise residential buildings, and realize the integration of solar water heating system and residential buildings, it is mainly from these two aspects to solve the problem of combining solar water heating system with the appearance of high-rise residential buildings and residential indoor water systems.

Read more: What are the problems with the use and promotion of solar water heating systems?