EKO MP-11, Instruction Manual

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EKO INSTRUMENTS CO., LTD. I-V Curve Checker MP-11 Instruction Manual Ver.7 Pg. 34
7. I-V Curve shape and possible cause
The I-V curve gives useful information on the performance of PV arrays, strings and modules through the shape of
the I-V curve and measured parameters. It also provides additional details of the PV device
’s environmental
conditions, such as irradiance, temperature, shade, unexpected error and so on.
This chapter shows some examples of I-V curve shape and suggestions of possible cause.
Note: Suggestions shows possible cause only. There are other reasons that cause a particular I-V shape.
7 - 1 . I - V c u r v e s h a p e a n d p o s s i b l e c a u s e
・
Thin line: Ideal I-V curve for reference
・
Bold line: Measured I-V curve
1) Good and standard measurement
2) Curve doesn
’t start from Y-axis (V=0)
・
Very short sweep time with higher Isc and lower
Voc compensating reverse bias effect (There is no
error on I-V curve itself)
3)
Unexpected shape with stepped missing part
・
A few modules (or clusters) with low irradiation or
small shadow.
I
V