Lock-in and pulsed thermography for solar cell testing.

Area of Science:

• Materials Science
• Semiconductor Physics
• Photovoltaics

Background:

• Solar cell inspection is critical for photovoltaic module performance.
• Defects, even minor ones, significantly impact efficiency.
• LED illuminated lock-in (LEDILIT) is a common inspection method.

Purpose of the Study:

• To evaluate flash-pulse thermography (FPT) for multicrystalline solar cell defect inspection.
• To compare FPT with the established LEDILIT technique.
• To determine the suitability of FPT for detecting various solar cell defects.

Main Methods:

• Comparative analysis of LED illuminated lock-in (LEDILIT) and flash-pulse thermography (FPT).
• Experimental setup description for both thermographic techniques.
• Inspection of multicrystalline solar cells with induced and natural defects.

Main Results:

• LEDILIT effectively detected local shunts, cracks, and laser-induced defects related to the photovoltaic effect.
• FPT identified only the most significant shunts and laser-induced defects.
• FPT revealed a subsurface inhomogeneity not detected by LEDILIT, indicating its potential for non-photovoltaic related defect detection.

Conclusions:

• LEDILIT is superior for detecting defects impacting the photovoltaic effect in solar cells.
• FPT offers a faster inspection alternative, capable of identifying certain defects and subsurface issues.
• The choice between LEDILIT and FPT depends on the specific inspection requirements and defect types.