The Tianfeng solar water heater is also a trap.
Solar water heaters are too boring. They are hot in summer and cannot be used in winter.
When you don't need hot water in summer, drop the water from the solar panel. It will be hot enough to remove chicken feathers. When using hot water in winter, pipes often freeze and clog, making it impossible to drain the water.
Even though the water can be deposited, due to the sun's rays in winter, the water temperature is generally not high, reaching 50 or 60 degrees at most.
Especially in some places where rainy weather is common, if it is not used for two or three days, the water in the sun will not be different from the outside. It is only available in spring and autumn and can be used most of the time.