With the rapid development of China's economy, energy shortage, environmental damage and other issues are highlighted. The former energy system has already been far from being able to meet the needs of the industry and urban residents. The constant rising of the gas price makes many families and companies choose new renewable energy, including solar energy as the first choice. Solar energy is confronted with enormous room for development against the backdrop of lacking gas supplies and encouraging environmental protection,. At present, solar energy is most widely applied in solar water heaters. However, solar water heaters rely on the sunlight to heat the water up and it heats the water up slowly, so it can’t heat anything up at any time like the electrical water heater or the gas water heater. After the water inside the water tank is used up, more water must be added to it by hand. This problem is more serious especially in winter or rainy days, which seriously hinders the popularization and development of the solar water heater.
This design mainly settles the difficulties such as that it is not convenient to add the water to the solar water heater’s water tank and the solar water heater can’t be used in cloudy or rainy days. The use of 51 MCU, DS18B20, DS1302, 1602 LCD, solenoid valves and so on performs the functions such as controlling the water automatically, showing the water temperature and the water level, heating the water up automatically when the water temperature is not high enough and protecting the water from boiling away.