I-V400w - I-V500w - SOLAR I-Vw - SOLAR I-Ve
EN - 74
Steps in the I-V curve
Small or partial shading of one
module of the string under test
Reflections
Random
environmental
contaminants on modules (soiling,
dirt, snow, debris, etc.)
Strong current mismatch
Cracks of cells or glass
Burn marks
Remove obstructions
Re-test when un-shaded
Remove reflections
Clean the modules
Check the current match
Replace affected modules
Characteristic curve not linear
Unsteady irradiation during
measurement
Leopard spot clouds shading the
modules
Low
irradiation
during
measurement
Re-test when clouds are
gone
Repeat measurement at an
irradiation of minimum
700W/m
2
(IEC/EN61829)