Solmetric PVA-1000S, User Manual

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7 Interpreting Measured I-V Curves
7-19
Electrical Interconnections in the Array Are Resistive
Electrical connections anywhere along the current path can add resistance to the circuit.
Assure that connectors between modules are fully inserted. Also check for signs of
corrosion in J-boxes and combiners.
Series Resistance of PV Modules Has Increased
Certain degradation mechanisms can increase the amount of series resistance of a
particular module. Corrosion of metal terminals in the module connectors, in the module
junction box, or on the interconnects between cells may increase series resistance.
Corrosion damage is more common in aged modules in humid or coastal environments.
Manufacturing defects within the module can also result in poorly interconnected solar
cells. If you see a burn mark along one of the module's internal ribbon conductors, it may
be an indication that an interconnection is becoming more resistive. These burn marks
tend to be located at the connection of two spans of internal ribbon conductors, or at the
interconnection between these ribbons and the PV module cords.
Before deciding that
excess resistance comes from these sources, be sure to properly account for PV wiring
resistance in the model, and check the electrical connections external to the PV modules
for signs of damage, corrosion, or heating.