Design and implementation of solar energy water heater controller

Abstract: A fully automatic solar water heater controller is designed. The system uses low-power and high-performance RISC microcontroller AVR as the core of the control circuit to monitor water temperature and water level in real time. It can realize temperature and water level detection management, fault and related alarm prompts, etc. It uses E2 PROM to save the set parameters and has a power-off memory function. After power failure, the parameters do not need to be reset. This fully automatic solar water heater controller has the characteristics of easy use, high stability, energy saving, and high practicality.

0 Introduction

With the improvement of people's living standards, the use of various water heaters has become quite popular, and the corresponding control instruments have also come out one after another. However, the various water heater control circuits on the market are still far from the ideal requirements. Consumers need real fully automatic control to achieve the simplest use, just like home TVs and refrigerators, just turn on the power and set it up, and then you don't have to worry about it. In view of the continuous expansion of the domestic solar water heater market, and the urgent need for improvement of the corresponding controller, this solar water heater controller was developed. The solar water heater designed in this paper uses AVR Meg a 32 single-chip microcomputer as the detection and control core, which not only realizes the real-time display function of temperature and water level parameters, but also has the function of temperature setting and control. The controller can use the auxiliary heating device to make the water temperature in the water tank reach the preset temperature according to the weather conditions, so as to achieve the purpose of 24-hour hot water supply. The actual application results show that compared with the previous display instrument, the controller has the advantages of high cost performance, high temperature control and display accuracy, easy use and stable performance, which improves the control level of solar energy application in China and has considerable economic and social benefits.

1 Design goals and implementation plan description

1. 1 System schematic diagram

The system schematic diagram is shown in Figure 1. Among them: W is the water level sensor (pressure type), including T2; T1 is the collector top temperature sensor; T2 is the water tank temperature sensor, which is integrated with the water level W; T3 is the antifreeze circulation temperature sensor (installed at the lowest temperature point of the collector circulation pipeline); T4 is the water pipe temperature sensor (installed at the lowest temperature point of the water circulation pipeline); T5 is the pipeline electric heating temperature control sensor (generally installed in the tap water supply pipeline, the position can be determined according to the actual situation); P1 is the collector pipeline circulation pump, which also serves as an antifreeze circulation pump; P2 is the water pipeline circulation pump (it can also be in the form of solenoid valve + automatic booster pump); E1 is the water supply solenoid valve (tap water directly enters the water tank for water replenishment); E2 is the top water solenoid valve (tap water enters the collector, and the top water enters the water tank); EH1 is the electric heater; EH2 is the electric heating belt (optional).

System schematic diagram

Figure 1 System schematic diagram.