Process and technology development for back contact silicon solar cells

Back contact solar cells promise several advantages over conventional solar cells such as easier module fabrication, higher efficiencies and excellent optical appearance. We investigated several industrial processing sequences for the manufacturing of emitter wrap through, metallization wrap through (η=17.2%) and metallization wrap around (η=17.5%) solar cells. These new devices require novel process technologies for the definition of rectifying p/n junctions on the rear. Therefore three different methods were applied in EWT solar cells: screen printed diffusion barriers (η=16.1%, screen printed metallization, 10×10cm²), laser patterning of a dielectric (η=16.6%, buried contacts, 5×5cm²) and P-Al co-diffusion (η=10.1%, no ARC, 5×5cm²). Additionally, the EWT concept was applied to monolithically integrated high voltage solar cells.