Cell Interconnection

In a PV module, solar cells are electrically connected to strings. The interconnection causes ohmic and optical losses in a module and affects the product reliability. In our Module Technology Center (Module-TEC) we use various soldering technologies and industrial stringing equipment for

• 3, 4 and 5 busbars
  
• Full- and half-sized cells
• Heterojunction cells
• Optically enhanced ribbons
• Multi-Wire interconnection
• Conductive adhesives
• Shingle interconnection
• Shaped ribbons and wires for back contact cells
• MWT cell interconnection through conductive backsheets

Measuring and optimizing the quality of the joints is primary to implement stable interconnection processes. With access to a wide range of characterization tools we have established specific analysis procedures:

• Mechanical, optical and microstructural characterization of ribbons
• Cross-section preparation and metallographic inspection
• Optical microscopy and SEM
• X-ray and 3D-µ computer tomography
• Scanning acoustic microscopy for void detection
• Kinetics of intermetallic phase formation
• Electrical resistance mappings, electroluminescence
• Peel force measurement at 90° and 180° peel angle
• Conversion of peel forces into adhesive fracture energies
• SmartCalc.Peel software for fast processing of peel test data
• SmartCalc.CTM for ribbon dimensioning
• Finite-Element-Modeling of stresses in solder joints
• Finite-Element-Modeling of current flow