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[on:]

Hello,

I'm new here in the Forum and I'm not sure if this is the right section, but anyway ;-)

I'm a student from Switzerland. As a school project I have built some dye-sensitized solar cells. Now I want to build a measuring system for these cells with an Arduino board (to measure the IV-curve of the cells).
In the Internet I searched for a kind of Sourcemeter builded with an Arduino controller and I have found this article about building a DIY IV Tester with Arduino:
http://pv.mit.edu/education/ivtester/

The resolution (for the current) of this IV Tester is +/- 30mA. My solar cells are really small - and not as efficient as a silizium solar cell - for that I only get a current in the range of about 50-200 micro-Ampère...
Now my question: Is it possible to modify this DIY IV Tester to be able to measure µA (micro-Ampère)?
Or is there a better solution for measuring the IV-curve of my solar cells in the range of µA?

I would welcome your response!

Sincerely
Felix

[Reply #1 on:]

hi,

first off, i do not have a out of the box solution for you, but maybe help in your search.

the way the circuit works is by measuring the voltage drop across a precise resistor which is in series with the load and then, using essentially ohms law,  convert the voltage drop to current. the resistor is often referred to as shunt resistor. this is how multimeters do current measurements as well.

the op amps like they are used in the circuit do pretty much the same thing, but they also give the voltage dropped across the resistor back to the circuit. that's why they are connected to the 5V line as well.

this video gives not a bad explanation on the subject

it should be possible to measure uAmps.