the best brand of solar energy is Huang Ming, made in Dezhou, Shandong province. The advantage is that even if it is sunny in winter, you can take a bath in one day, but the disadvantage is that it is too expensive. Other prices are similar, and the better ones are Linoret, Sang Le and Four Seasons Pastoral. I have used all these kinds except Linorette's. Basically you can take a bath in 2-3 days in winter. Moreover, these brands are old factories that make solar energy, and the quality is good.

if 3-4 people take a bath, use more than 2L, because the net capacity of 2l is only 18l, which is just enough for 2-3 people to take a bath in winter. It's more wastewater for our family to take a bath.

as for many people who claim that purified water has no scale, don't worry about it, all of them have scale. Now one is the temperature control meter. If it is not the original temperature control meter, then choose TMC, which is reliable in quality.

Choosing a dealer is also a matter of learning. Many roadside advertising phones are very cheap, but it is not cost-effective to install this one for money and that one for money. Remember, it is the most expensive to buy the tracing belt, one meter for the water pipe 8 yuan, about 3 for the thermostat tmc with automatic start of tracing belt, 35 with heating (including solenoid valves and sensor wires, etc.), just within 12 tee joints, and one meter for the thermal insulation pipe. Pay attention to its installation quality, otherwise there will be endless troubles.

good luck.