What is the reason why the solar water heater is ninety degrees in rainy days?

There are two reasons why the solar water temperature is 90 degrees in rainy days:

1, the weather is fine and sunny before it rains, and the water in the solar water tank can reach 90 degrees or even boil, but hot water is rarely used or used, resulting in heat accumulation. In addition, the water tank has insulation layer, so the heat loss is very small, and the temperature drop between day and night does not exceed 5 degrees. So it is normal to keep the water temperature of the water tank at 90 degrees the next day or even the third day, which shows that the quality of solar energy you choose is still very good.

2. Sensor failure. When the sensor fails or the sensor circuit is damaged, the sensed water level may be inaccurate. I suggest you put hot water on it. If the water temperature is really high, that's fine. If there is no hot water or the temperature is not high, it is a sensor failure, and the sensor needs to be replaced or the circuit needs to be repaired.