Laser structuring of the 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 2-terminal (2T) approach combining silicon heterojunction (SHJ) and wide bandgap Cu(In,Ga)(Se,S)₂ (CIGS). The energy gap of the CIGS layer can be adjusted by optimizing its composition. This flexibility is particularly beneficial when producing monolithic 2T panels, which require matching the currents obtained in the upper and lower cells in order to maximize the output power. SITA aims to create efficient tandem modules with efficiency exceeding 30%.
Importance of monolithic laser connection in 2T tandem architecture
In the 2T tandem architecture, monolithic laser-structured interconnects eliminate the need for additional external cabling, thereby reducing electrical losses and increasing module efficiency.
Cu(In,Ga)(Se,S)₂ cell on a 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 of up to 30%. The transparent ITO layer allows more light to reach the underlying silicon cell. This configuration optimizes the use of the sunlight emission spectrum, significantly increasing the maximum efficiency of the module. The wide bandgap of a CIGS cell complements the energy conversion capacity of a narrower bandgap silicon cell, enabling the tandem cell to operate efficiently over a wide range of light wavelengths.
A milestone in the SITA project: laser structuring of CIGS modules in monolithic modules
Roltec has contributed to another SITA milestone by successfully developing and implementing laser module structuring. 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 increase the durability and performance of the modules in real outdoor conditions. The precision of the laser structuring process also increases the usable surface area of the modules, further improving their maximum efficiency.
Future perspectives
Roltec, in cooperation with other partners in the SITA project, is committed to promoting innovation in the field of photovoltaics. The achievements so far constitute significant progress towards the energy transition to renewable sources. Stay tuned with us for further updates on this initiative.
