This project is designed to measure parameters of solar panels and objective is to measure Voltage, current, power, temperature and intensity of light .Digital display is used to display values of these parameters.Pic microcontroller is used to measure analalog values of these sensors and PIC microcontroller built in analog to digital to converter is used to measure values of these parameters. I have written this article on request of one follower of my blog.You can also ask me to write article you need.
The block diagram above shows a solar panel measurement system. Voltage divider is used to measure voltage.I have used polar and not polar capacitor along with voltage divider to avoid fast voltage fluctuations in voltage during measurement. Difference amplifier is used to measure current. Signal conditioning is done by using shunt resistor to convert current into voltage form. Lm35 tempertuare sensor is used to measure voltage of solar panel. Light dependent resistor is used to measure light intensity. Power can be calculated by product of measured current and voltage.
As shown in above block diagram sensors are connected with four ADC channels with PIC micrcontroller. Next I have explained how these sensors works and circuit diagrams of all these sensors is shown below.
Voltage sensor circuit diagram :
There are many ways to sense voltage. But in this project we can easily measured voltage of solar panel using voltage divider. Two capacitors are connect parallel to voltage measurement resistor to avoid voltage fluctuation and avoid harmonics to go into ADC of PIC microcontroller.I have already posted a article on how to measure AC voltage using PIC microcontroller. You can also check this article by clicking on link below:
Circuit diagram of voltage sensor is shown below:
According to voltage sensor formula ,for solar panel of 24 volt values of voltage divider resistors are R2 = 10K and R4 = 2K. The reason I have used voltage divider because the maximum input voltage to Analog to digital converter can never be greater than 5 volt. But I calculated these resistor values according to 4 volt to increase accuracy of measurement and to insure protection of ADC in case of greater voltage fluctuation.
Note: DC voltage source is used instead of solar panel in Proteus just for simulation purpose. Because solar panel simulation is not available in Proteus.
current sensor circuit diagram :
Below is a circuit diagram of current measurement circuit. I have used difference amplifier to amplify voltage appearing across shunt resistor. Because current value may be too high and too low in different timings and different voltage will generate across shunt resistor.So it is not possible to use voltage divider as we don’t know the values of current.
I have already posted a article on how to measure AC current using difference amplifier. You can check following article to understand how above circuit is working.
Temperature sensor circuit diagram :
Circuit Diagram of temperature sensor is shown below. To know more about temperature sensor and its details go through following articles:
Light sensor circuit diagram :
Light dependent resistor is used to measured intensity of light. LDR is a light controlled variable resistor.Resistance of LDR changes with the change in intensity of light. Greater the intensity of light, lower will be the resistance and lower the intensity of light, greater will be the resistance. Change in resistance can be easily measured by converting it into voltage form as shown in circuit diagram below.
In above circuit non polar 100nf capacitor is used to avoid voltage fluctuations.
Power measurement :
Output power of solar panel can be easily calculated by product of voltage and current output of solar panel.Because solar panel is a DC voltage source and in case of DC, voltage and current remain in phase and power relation become simple which is just a product of voltage and current. These calculations can be easily done with the help of algorithm/program.
Complete circuit diagram:
Complete circuit diagram of solar panel voltage measurement is shown blow. you can easily write code for this circuit using ADC of pic microcontroller and lcd display for digital display of these values.if you still have any issue after reading this article, feel free to comment on this post. Don’t forget to subscribe to my blog to get updates of new posts in your inbox.
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