[Types of solar water heaters] Solar water heaters can be roughly divided into the following categories: 1. From the heat collection part: (1) Glass vacuum tube solar water heater: it can be subdivided into all-glass vacuum tube type, heat tube vacuum tube type, U-tube vacuum tube type/vacuum tube heat collection and heat storage integrated type. The most commonly used is the all-glass vacuum tube type, which has the advantages of safety, energy saving, environmental protection and economy. Especially the solar water heater with auxiliary electric heating function, which uses solar energy as the main energy and electric energy as the supplementary energy makes the solar water heater operate normally around the clock throughout the year, and the efficiency is still relatively high when the ambient temperature is low. The disadvantage is that the volume is relatively large, the glass tube is fragile, the scale is easy to accumulate in the tube, and it cannot be operated under pressure. (2) Flat-plate solar water heaters: can be divided into tube plate type, wing tube type, snake tube type, flat box type, round tube type and heat pipe type. Its advantages: it has the advantages of good integrity, long life, fewer failures, low safety hazards, pressure-bearing operation, safe and reliable, large heat-absorbing body area, easy to integrate with buildings, strong resistance to dry air, etc. The performance is also very stable. The disadvantage is that the cover plate is non-vacuum and the heat preservation performance is poor. Therefore, the heat collection performance is poor when the ambient temperature is low, and the auxiliary heating is relatively power-consuming. The thermal efficiency is lower when the ambient temperature is low or the outlet water temperature is required to be high. If it is damaged by freezing, the entire collector plate needs to be replaced, which is suitable for the southern regions where there is no freezing in winter. (3) Ceramic hollow flat plate solar water heater: The ceramic solar panel is a hollow thin-walled flat box solar collector with ordinary ceramic as the base and three-dimensional mesh vanadium titanium black porcelain as the surface layer. The ceramic solar panel is made of porcelain material as a whole, which is impermeable, impermeable, high strength, good rigidity, non-corrosive, non-aging, non-fading, non-toxic, harmless, non-radioactive, sunlight absorption rate will not decay, and has a long-term high The light-to-heat conversion efficiency. Tested by the National Solar Water Heater Quality Supervision and Inspection Center, the solar absorption ratio of ceramic solar panels is 0.95, and the daily heat gain of the concrete structure ceramic solar roof is 8.6MJ, which is much higher than the national standard. Ceramic solar panels have low manufacturing and use costs, and the sunlight absorption ratio is not attenuated. It has the same life span as the building. It can be used to share structural layers, insulation layers, and waterproof layers with the original roof. The structure is simple and the heat insulation effect is better than the original roof. The concrete structure ceramic solar roof, sun facing wall and balcony guardrail surface integrated with the building provide hot water, heating and air conditioning for the building; provide heat energy for industry, agriculture, and aquaculture; it can be used for large-scale solar hot water power generation and wind in the desert. Road power generation, desalination of sea water, desalination of brackish water, and turning deserts into farmland. 2. Classification from structure: (1) Compact solar water heater: Insert the vacuum glass tube directly into the water tank, and use the circulation of heating water to increase the water temperature in the water tank. This is the most conventional solar water heater in the market. (2) Split-type water heater: The split-type water heater separates the collector from the water tank, which can greatly increase the capacity of the solar water heater. It does not adopt the falling water working method and expands the scope of use. 3. Points from the pressure of the water tank: (1) Pressure-bearing solar water heaters: The outlet water of solar water heaters is under pressure. Generally, it is a top-water work, and a pressure-bearing water tank is not necessarily used. (2) Non-pressurized solar water heaters: ordinary solar water heaters are non-pressurized water heaters. Its water tank has a pipe that communicates with the atmosphere. It uses the height difference between the roof and the home to generate pressure when using water. Its safety, cost, and service life are much more significant than those of the pressure-bearing type. [Solar water heater] is a device that converts sunlight energy into heat energy, heating water from low temperature to high temperature to meet people's hot water use in life and production. According to the structure, solar water heaters are divided into vacuum tube solar water heaters and flat panel solar water heaters, mainly vacuum tube solar water heaters, occupying 95% of the domestic market share. Vacuum tube domestic solar water heaters are composed of heat collection tubes, water storage tanks, brackets and other related parts. The conversion of solar energy into heat mainly relies on vacuum heat collection tubes. The vacuum heat collection tubes use the principle of hot water floating and cold water sinking to make the water produce micro-circulation. Reach the required hot water.