Renewable energy solar power can be divided into solar power (also called photovoltaic) and solar thermal power generation two categories, the latter more complex as technology can only be used for larger capacity, has limited application, so the practical application of the present less.dell inspiron 1525 battery Solar power is inexhaustible, pollution-free and many other advantages, has become a hot human quest for new energy. But there is also applied intermittently, power generation and climate-related shortcomings. Therefore, to enhance the utilization of solar cells, power generation real-time monitoring is necessary, and can work in the early detection of solar cells appear abnormal. Here presents a real-time monitoring of solar cell power generation system design. System using AT89S52 MCU, using current sensor on the solar cell’s output current measurement, the advantage is almost no energy in case, to measure current into voltage.
1 Hardware system design
Hardware circuit shown in Figure 1, mainly by the solar cell group, consisting of Hall current sensors, I / U conversion circuit, liquid crystal display device composed 1602, AT89S52 chip microprocessor control system, and the composition of lead-acid battery energy storage System 5 parts. Course of their work: when the solar cell receiving light to produce current, the battery charging, MCU through the regulator device provided by the battery voltage, the electricity generated from solar cells on the real-time signal acquisition. As the MCU can only receive the voltage signal, so before receiving the signal from the I / U, U / U conversion module will signal transferred to the appropriate voltage. The internal operation, resulting in delivery device 1602 LCD display the battery capacity
1.1 A / D converter module
When the analog signal input after the need microcontroller is converted to digital signals, the need for simultaneous measurement of solar cell output voltage and current, so it ADC0832 is an 8 bit serial pair of channel A / D converter device, A / D conversion precision depends on the high stability degree of baseline reference voltage, reference voltage is set to 5 V, generated by the TL431. RC filter after the analog signal input into the AD, then after the serial output ADC.
1.2 I / U Converter Module
For MCU I / O interfaces can only receive 0 ~ 5 V voltage signals, real-time capture solar cell output current required to convert the current signal voltage signal, as the system is the photovoltaic system, auxiliary equipment, power consumption is as low as possible primary problem. Hall current sensor thus become the first choice, according to Hall-effect theory to work, almost no energy in the case of the current signal into voltage signal. The system uses TBCl0SY type Hall current sensor, rated output voltage (± 4 ± 0.5%) V, ± 15 V dual power supply, measuring current range of O ~ 15 A, can basically meet the small off-grid PV systems application.
1.3 Power Supply
MCU running the need for on-chip FET transistors or the supply of power to work in the corresponding state. AT89S52 requires a 5 V power supply (the actual working voltage is 3.6 ~ 6.0 V). Available rectifier, regulator mode power supply, the voltage was 4.5 V or so, because the system is independent power generation, and long-term use, taking into account the power life of the device to provide the municipal electric or battery-driven power supply is not realistic, the most good program should be within the system’s battery-powered solar cells, regulated by the regulator block and 7805 for the 5 V, Vcc input pin MCU, MCU and LCD driver devices. TBCl0SY Hall current sensors, need to ± 15 V dual power supply, the same, the battery power supply within the system. The Regulator Manifold 7805,7915 regulator in ± 15 V, and thus drive their work.
1.4 Output Display Module
Charge is calculated as Q = UIT, which needs time T can make their own determination in the software programming, such as every 3 min sampling time, the internal operations by 1602 LCD evacuation capacity. To save energy, by setting the relays, so that liquid crystal display automatically after 10 s off.
2 System Software
System Software primarily completed by the microcontroller, data acquisition and control of the main display, the software system design is modular thinking, its measurement and display the program flow shown in Figure 2.
3 System Test and Analysis
To 200 W of the small off-grid photovoltaic systems, for example, the rated voltage of 24 V, maximum current of 6.18 A, battery 200 Ah. Design of the normal discharge time for the 2 ~ 3 d, 0 ~ 6.18 A proportion of current is converted to 0 ~ 5 V voltage, resistance posed by the two attenuator, the output voltage amplification ratio of the resistors R1 and R2, the ratio of the decision , set U / U conversion ratio of 5 / 24, then R7 = 10 kΩ, R6 + Rp2 = 48 kΩ. Depending on the charge formula Q = UIT, test time is 12 noon to 2 pm, starting from the display power consumption, recorded once every 3 min and monitoring the actual power of the data shown by the system, the second error of less than 3%, table l 10 are given the initial measurement error situation, with the power increases, the error range is gradually shrinking.
Renewable energy solar power can be divided into solar power (also called photovoltaic) and solar thermal power generation two categories, the latter more complex as technology can only be used for larger capacity, has limited application, so the practical application of the present less. Solar power is inexhaustible, pollution-free and many other advantages, has become a hot human quest for new energy. But there is also applied intermittently, power generation and climate-related shortcomings. Therefore, to enhance the utilization of solar cells, power generation real-time monitoring is necessary, and can work in the early detection of solar cells appear abnormal. Here presents a real-time monitoring of solar cell power generation system design. System using AT89S52 MCU, using current sensor on the solar cell’s output current measurement, the advantage is almost no energy in case, to measure current into voltage.
4 Conclusion
The AT89S52 microcontroller, Hall current sensors and liquid crystal composition 1602 solar power generation, real-time monitoring system is simple, low cost, maintenance-free, small power consumption and effective real-time monitoring of solar cell power generation, early detection of solar cells anomalies arising in the work. The system is designed as a photovoltaic system accessories for small off-grid photovoltaic systems, and components of the system, longer life, durable and reliable, so in the off-grid PV system has wide application.