problem in opamp for I-V converter

[HARRISH]

hi.i want to measure the current from solar panel and i ve to send it to microcontroller for MPPT project. the problem is that am using 18W panel of rating 21V and max 1A. which ic has to b used? can i use opamp?

 

[crutschow]

An op amp can be used if you can measure the current in the ground side of the solar panel current. For that you just connect a small resistor in series with the common line an measure the voltage across it. For 1A, a 50mΩ (shunt) resistor will give a 50mV drop which can be readily amplified by an low-offset rail-rail op amp such as the LT1637 or MCP601.

 

[Nick_F]

You obviously need a current shunt to measure the current provided by the solar panel. Once you have the shunt (let's say 0.1ohm), you can use any method to measure the voltage on the shunt and by applying Ohms law you get the current. You can use an opamp to further amplify the voltage on the shunt, for example to have the voltage on the shunt (maximum 0.1V at 1A) converted to 5V, which you can measure with any voltmeter or with the ADC from a microcontroller.