How should residents in Zhongshan, Guangdong choose solar water heaters?

For a family of four, 20 tubes of solar energy are enough. If your family often takes a bath in a bathtub, you need a lot of solar energy. It is estimated that at least 30 pipes are needed. Your solar energy in Guangdong is very expensive, and our solar energy in Jiangsu is very cheap. Before, Guangdong users pretended to be customers and ordered a prototype from the factory. At that time, the price of our prototype was 10% off the normal ex-factory price, so it was much cheaper than buying it from local retailers, hehe.