Photoelectric complementarity, in fact, can not be properly achieved. Market 90% of solar water heaters have insurmountable stubborn disease: Winter water temperature can not reach, or only produce a small amount of hot water; These products can only be used in summer and autumn when the sun is plentiful, the winter sunshine is weak at all can not be used, or produce too little hot water, not easy to use, customers often complain; Real solar water heaters must be available all year round. The use of hot water is relatively large time is concentrated in winter, and winter heat collection effect can not meet the requirements of use, basically limited by climatic conditions, can not get rid of the limitations of ordinary solar water heaters "Sky", it is difficult to ensure that there is still plenty of hot water in winter. Many solar dealers need to increase electrical aid or oil boilers in order to make up for the lack of hot water production, but this makes a double investment and increases the financial burden on customers. Consumers will waste a lot of electricity when they actually use it, and further reduce the comfort of their use. Solar water heater in order to have hot water in the sun shortage weather, the basic use of the so-called "photoelectric complementary" technology, that is, in the solar water heater on the addition of an electric heater. Theoretically, as long as there is not enough hot water, you can "let" the electric pipe heat. That sounds beautiful. In fact, because consumers use hot water mode is very complex, 365 days a year sunshine situation is not fixed. So there is no way to properly solve the "when to start electric heating is the most appropriate." The use of temperature control, time control is not actually possible (because sunny weather just bet on the tap water temperature is also lower than the set temperature, if only the use of temperature control, then will not need electric heating when also electrified).
So that the first seemingly simple "electric heating control" problem without any solar manufacturers to improve the solution-100% of the solar manufacturers are counted. There is also a serious drawback is that more than 99% of the market is now very backward "non-pressurized" (including a number of strong brands in the field of solar water heaters, sales are all this non-pressurized type), commonly known as "falling water type."
Its water intake, effluent only a water pipe, the use is very inconvenient, there is no comfort at all.