T-cells are short for metallization wrap-through (MWT) silicon solar cells.
MWT technology is the method developed by Solland Solar, the largest solar cell manufacturer in the Netherlands, for its Sunweb battery. This technique uses P-type polysilicon to transfer the energy collected on the front of the battery through the battery to the back of the battery by laser drilling. This method increases the output efficiency of each cell by 2%, and is connected to the battery module, resulting in an increase in output efficiency of 9%.
In the MWT device, the difficulty of the process includes: the alignment and repeatability of laser drilling and grooving isolation, the control of the size and shape of the hole, the damage caused by the laser and the silicon substrate, and the filling of the metal in the hole. Normally MWT requires about 200 through holes per wafer.
MWT battery production process is roughly:
Wafer -> Laser Perforation -> Cleaning & Texturing -> Emitter Diffusion -> To PSG -> Deposit SIN-> Print Front Electrode -> Print Back Electrodes -> Print Back E-field -> Sinter -> Laser Insulation -> Test .