Industry related approaches for bifacial p-type PERX solar cells

Abstract

The authors discuss industry related approaches at Fraunhofer ISE for bifacial p-type silicon solar cells, taking into account the well-known “passivated emitter and rear cell” (PERC), “passivated emitter and rear totally diffused” (PERT) and “passivated emitter and locally diffused” (PERL) architectures. In the case of PERC, challenges in terms of alignment, printability and the importance of bifaciality are addressed. In the case of PERT, a co-diffusion process is utilized to form the emitter and the back surface field simultaneously avoiding also critical shunts that can arise at the edges of such devices. For the PERL technology, the industrial feasible pPassDop approach is discussed. We report on front side energy conversion efficiencies for PERC of 21.4%, PERT of 20.5%, and PERL of 19.8%. Furthermore, bifaciality factors for PERC of 0.7, for PERT of 0.86, and for PERL of 0.89 are presented.

In Situ Solar Wafer Temperature Measurement during Firing Process via Inline IR Thermography

“…First, wafers with a standard full area Al rear contact with and without a standard H‐pattern Ag grid (called “grid”) front contact (“monofacial” configuration) were investigated, as this type represents the industrial standard type, making up the lion share of PERC production. Second, wafers with an Al grid rear contact with and without an Ag grid (“bifacial” configuration) were studied, as this type grows annually in market share within the PERC section. Finally, nonmetallized wafers were investigated as well, as this configuration serves as an important test structure for quality assurance of PERC precursors .…”

High‐precision alignment procedures for patterning processes in solar cell production

“…Aligning two or more processes with each other is a task that is of relevance in the production of multiple solar cell designs. A prime example is the fabrication of p ‐type silicon bifacial passivated emitter and rear cells (biPERCs) with particularly narrow rear side aluminum contact fingers . Because of ever‐smaller finger widths of the aluminum grid, the significance of an accurate alignment to the previously generated laser contact openings (LCOs) of the passivation layer becomes more and more relevant.…”