Extract AC current from AC/DC current generated by a solar module
This is the situation you've described so far:







simulate this circuit &ndash; Schematic created using CircuitLab

R1 is your sense resistor, which converts your 5-80 &micro;A AC current into a 5-80 mV AC voltage, which should be easy to measure.

Now, what kind of component can you put at U1 that will pass the DC current, but have minimal effect on the AC measurement?

What effect does C1 have on the measurement?

(Hint: U1 could also be a 4-terminal device, in which case, it could be physically much smaller.)