# Measurement of current output from solar panel using PIC16F877A, ACS712 hall effect

#### noel_t

May 31, 2011
4
Dear Friends,

Project Description: Data Acquisition System for Solar Panel

In fact, i need to measure the current from solar panel and display it on the LCD.

I am using PIC16F877A with C language to do so. For the Temperature, Light, and Voltage, there is no issue of reading the sensors and it is working perfectly. However, ACS712 hall effect sensor is mentioned to be a good solution for DC current measurement in the datasheet as well as having a linearity characteristic, but the time i am using it with PIC, it does not give me a true value within at least 0-50 A input ranges.

lcd_goto(44);
current=0.074*current;
current=(current-37.888);
current=current/2;

dis_num(current);
send_char('.');
dis_num(current%10);

send_char(' ');
send_char('A');
send_char(' ');

#### Attachments

• proteus.jpg
74.6 KB · Views: 5,441

#### (*steve*)

##### ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,510
Perhaps you could do the work for us and tell us what range of voltages you're measuring (in theory) from this device, and what you're seeing from the ADC (raw values would be best, but your calculated values would be OK.

#### noel_t

May 31, 2011
4
Perhaps you could do the work for us and tell us what range of voltages you're measuring (in theory) from this device, and what you're seeing from the ADC (raw values would be best, but your calculated values would be OK.
In fact, the voltage is quite flexible for measuring and any voltage can be measured for wide varieties of solar panels. Here the problem is only the current measurement which is not that accurate which is expected to be. Based on my perception, for a reliable data acquisition system for solar panel, it must provide close values to the actual value.
If you don't mind i can send you the PROTEUS file+HEX to see the operation of the circuit and values. Please let me know.

#### (*steve*)

##### ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,510

What range of voltages are you measuring (using the uC's ADC) from the Hall effect device... And so on for the rest of my question above...

#### noel_t

May 31, 2011
4

What range of voltages are you measuring (using the uC's ADC) from the Hall effect device... And so on for the rest of my question above...

The raw values are 2.25 to 4.64 V. After increasing the current(input of ACS712), still the same voltage appears across the output of the current sensor.

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