The National Solar Energy Institute (INES), part of the French Alternative Energies and Atomic Energy Commission (CEA), has developed a new heterojunction (HJT) solar module using Norway made silicon wafers and German polysilicon with low carbon intensity. With a carbon footprint of 317 kgCO2eq/kWp, the module is way down compared to 700 to 800 kgCO2eq/kW of Chinese products, it announced.
Calling it a demonstration module, the team says it has an average cell efficiency of 22.9% and a power output of 566 W. Since the module was manufactured in Germany, Norway and France with the 3 nations having a low carbon mix estimated at 650 gCO2eq/kWh, 29 gCO2eq/kWh and 52 gCO2eq/kWh respectively, it has a significantly lower CO2 value compared to China's carbon balance of 1,023 gCO2eq/kWh.
The low carbon footprint has been achieved not only because of local nature of manufacturing, but also with various other technological measures put in place by the team.
Norwegian silicon wafers were used with a thickness of 130 µm, instead of the conventional 170 µm. These were used for solar cells made with CEA's pilot line at INES in France with reduced quantity of indium and silver and critical metals.
The team also used a glass backsheet configuration adapted for the residential sector, for solar modules assembled in France using a thinner 2mm glass. Aluminium frame was replaced by a frame made of plant material, available in Europe and this frame alone reduced the CO2 footprint of the module by more than 50 kgCO2eq/kWp.
"To guarantee high efficiency, which is also a critical lever, the interconnection of the cells by a paving (or gapless) process has been favored. This eliminates the gap between the solar cells and interconnects them by creating a 1 mm overlap between cells while keeping the interconnection strips. It densifies the panel and increases its power per sqm (or conversion efficiency)," explains INES.
In addition, a design for recycle approach led to the choice of fluorine-free thermoplastic encapsulants and backsheets of European origin, which will facilitate recycling.
The institute stressed, "This achievement, which incorporates several innovations, makes our laboratories among the leaders in Europe."
Anis Jouini, General Director of INES, will present the keynote "Innovative Solar Modules – Today and Tomorrow" at the TaiyangNews Solar Module Innovations 2023 virtual conference on Jan. 31. Free registration here.