Laser structuring of a CIGS module with a transparent ITO BACK ELECTRODE
SITA Project Overview
The SITA project aims to deliver the next generation of inorganic tandem solar cells using a two-terminal (2T) approach, combining a silicon heterojunction (SHJ) with a wide-bandgap Cu(In,Ga)(Se,S)₂ (CIGS). The bandgap of the CIGS layer can be tailored by optimizing its composition. This flexibility is particularly beneficial for fabricating monolithic two-terminal solar panels, which require matching the currents of the top and bottom cells to maximize power output. SITA aims to create efficient tandem modules with efficiencies exceeding 30%.
The importance of monolithic laser interconnect in 2T tandem architecture
In the 2T tandem architecture, monolithic interconnects based on laser structuring eliminate the need for additional external wiring, thereby reducing electrical losses and increasing module efficiency.
Cu(In,Ga)(Se,S)₂ cell on transparent back contact
The top Cu(In,Ga)(Se,S)₂ cell, on a transparent back contact (such as ITO), is crucial to achieving the ambitious goal of creating a tandem photovoltaic module with an efficiency approaching 30%. The transparent ITO layer allows more light to reach the underlying silicon cell. This configuration optimizes the use of the solar emission spectrum, significantly increasing the module's maximum efficiency. The wide bandgap of the CIGS cell complements the energy conversion capacity of the narrower bandgap silicon cell, enabling the tandem cell to operate efficiently across a wide range of wavelengths.
SITA project milestone: laser structuring of CIGS modules in monolithic modules
Roltec has contributed to achieving another milestone in the SITA project by successfully developing and implementing laser structuring of modules. For SITA, this innovative technique had to be optimized by the Roltec research team for CIGS modules on transparent ITO electrodes. Laser-cut electrical connections and insulation enhance the durability and performance of the modules in real-world outdoor conditions. The precision of the laser structuring process also increases the usable surface area of the modules, further improving their maximum efficiency.
Future prospects
Roltec, in collaboration with other SITA project partners, is committed to promoting innovation in photovoltaics. The achievements to date represent significant progress towards an energy transition to renewable sources. Stay tuned for further updates on this initiative.
