Strange IV curve of solar cell measurement by 2651A

I used 2651A to do IV measurement for different solar cells with 4-wire connection. Some results of some solar cells are very strange as showed in the diagram. It seems that the IV curve are distorted.<br> When I used 2-wire connection to measure, the curves are fine but the result including the resistance.<br> Different solar cells will results different &quot;distortions&quot;. Not all the solar cells have this problem.&#160;<br> I found if we add some capacitor parallel to the solar cell, the distortion could be improved. However, it cannot be completely disappeared even I add a big capacitor (&gt;10000uF) for some solar cells.<br> I also use some other source meter to do the IV charaterization for solar cells, but I never met this problem before.<br> I would like to know why the source meter results this problem and how to solve it.<br> &#160;

Try turning on the high capacitance mode.<br> smua.source.highc = 1

Hi Andrea,<br> The high capacitance mode is on.