At the heart of innovation, TNO develops a new interconnection technology for bifacial back-contact solar modules and brings its expertise in environmental impact assessment
IBC4EU Partner Insights
TNO has recently developed a new bifacial interconnection technology for IBC cells based on a Light-Transmitting Conductive Substrate (LTCS). This LTCS technology replaces the conventional non-transparent copper backsheet, enabling the manufacture of back-contact PV modules with more than 80% bifaciality.
The module assembly processes are standard and follow the conventional back-contact module manufacturing process, including conductive adhesive deposition, lay-up of encapsulant layers, cells, front glass, and lamination.Therefore, it benefits from the advantages of TNO´s original conductive backsheet interconnection technology: high performance, simple and cost-effective processing, design flexibility, and suitability for all back-contact cell designs.
This interconnection technology presents itself as the ideal alternative to standard tabbing-stringing technology for manufacturing back-contact bifacial PV modules.
After a successful proof-of-concept on mini-modules up to 40 x 40 cm2, TNO is currently upscaling the bifacial back-contact interconnection technology to full-size modules.
Figure 1: Courtesy of TNO
Project Updates
TNO has contributed to a deliverable report in WP4 describing the different interconnection methods for IBC cells under study in the IBC4EU project, including tabbing-stringing, conductive backsheet, LTCS, and 3D interconnection. Based on this description, along with material/encapsulant characterization and a joint reliability experiment between partners, the most promising interconnection methods are selected for different module configurations (mono- or bifacial, multi-busbar, or busbarless). The status of the industrial versions of the interconnection methods developed within the project has been assessed. In addition, TNO is supporting Energyra in their efforts to manufacture a series of monofacial IBC modules based on conductive backsheet technology with their industrial manufacturing line.
As part of WP Sustainability, TNO is responsible for executing an environmental assessment of the innovations explored in the work packages related to wafer, cell, and module research within IBC4EU. The methodology includes collecting foreground data from partners and background data from the EcoInvent database, which is then used as input for the SimaPro platform with the impact assessment method (EN15804+A2). The key performance indicators for this initial assessment include global warming potential (in kg CO2 eq/kWp) and the use of critical raw materials such as Si and Ag. When combining innovations to construct a hypothetical module, the project aims to reach a CO2 impact of 230 kg CO2 eq/kWp