This type of hot water bottle is made of two materials, one is wool and silk waterproof fabric and the other is plastic waterproof fabric; the width is about 0.8 meters, the large one is about 1.4 meters long, and the small one is about 1.4 meters long, about 1.2 meters, each costs about 10-15 yuan. There is a water injection port at the top and a shower nozzle at the bottom. The color is black with strong heat absorption. When placed outdoors, the heat transferred from the sun can provide enough bathing water for a family of three. Made from high temperature resistant and anti-aging plastics processed by high frequency heat sealing
I am a practitioner of solar water heaters. I don't know if the solar hot water bottle you mentioned is the black plastic bag commonly used in Shandong and other areas for rooftop bathing. If that is the case,it's simple: it's a closed black plastic bag to which two pipes are connected, one for the water inlet and the other for the water return signal pipe. When using, first place the plastic bag on the roof with direct sunlight and use the tap water pipe to fill the plastic bag with water through the water pipes upper and lower. When the water is full, water will flow out of the signal pipe. , and the tap water will be turned off. As the black plastic bag absorbs heat easily, it naturally heats the water inside and can therefore be washed in the evening.
This thing is relatively cheap and can usually be bought for a few dozen yuan. However, since it cannot retain heat, it can only be used in summer, and due to the aging of rubber, it is used. Generally can only be used for one year.