Module Characterization

 

• Module Characterization
• Module IV (60 sweeps / hour)
• Angular response
• Performance Dependencies
• Indoor vs. Outdoor characterization

All RETC analysis can be done for any mounting
• Rack mounted Fixed tilt / Latitude tilt
• Single Axis (Horizontal or Tilt)
• Dual Axis
• Horizontal roof mounted
• Tilted roof mounted

Module manufacturing
• Increase in series resistance due to poor joints
• Cell mismatch
• Long term reliability
• EVA degradation (Yellowing, Hazing, delamination, moisture ingress, etc… )
• Solder Joint failure (most common cause of panel failure)
• Cell cracks (moduling process induced or cell inherent)
• Hot spot

 

 

Measurement of Temperature Coefficients: The crystals used to make PV cells, like all semiconductors, are sensitive to temperature.
A higher temperature coefficient means the panels produce less power at NOCT.

The example shows two arrays with power production vs. Irradiance. The blue array produces less under high irradiance due to a higher Tc

 

Rs losses come from many areas including:
- Wiring,
- Junction-box terminations
- Cell-interconnects
- Ribbons
- Cell metallization
- Emitter resistance
- Bulk resistance
- Cell solder bonds




Non uniform light dispersion on the panels manifests itself as increased Rs.

Processing can induce micro-cracks which will propagate and break the cells.

Mismatched cells can degrade further overtime due to extended over-biasing.

Once the panel diodes turn on, power is lost from the module and therefore reduces the overall output of the string.