Low voltage ratio Vmpp/Voc
• Voltage drop on cables to PV
module string
• Check cables, connectors,
contacts, and string wirings
• Check cable length and
cross section
• Check modules for bad
connections or oxidation
• Replace affected modules
• 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
• Remove the obstructions
• Remove obstructions
• Re-test when un-shaded
• Clean the modules
• Check that currents 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)
To Next Page
Loading...
Need help?
General
