Measuring current produced by Photodiode

Hi all,

I have a photodiode and I want to measure the open circuit voltage Voc and short circuit current Isc under illumination by sun.

Now Voc is when no load is attached, so I measured it by multimeter's lead across the photocell when under sun.

For Isc, what should I do?

I am also facing problems in determining current produced by the cell. That is if I attach a resistor in series to the photo diode and current across the resistor would be what generated by the photo diode. But how do I ground the other end of the photo diode if I am working outside the lab? Or is there any other method to measure that?

Thanks in advance

As with any source, you can take the complete loading curve by measuring the voltage across a variable load resistor connected to your photodiode.
If you use a calibrated potentiometer, you can calculate the voltage for any load-resistor value.
Such loading curve will show you the optimum load resistance for which, under a defined light irradiation, your photodiode generates a maximum power.