PERL, an abbreviation for Passivated Emitter Rear Locally-diffused solar cell, combines the advantages of PERC and PERT. As with PERC, the front surface as well as the rear surface of the monocrystalline cell are passivated, but the rear is locally diffused only at the metal contacts to minimize recombination while maintaining good electrical contact.

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Based on n-type material PERL cells have a long life expectancy and achieve an efficiency potential of 25 %. Combined with the per se bifaciality of this cell architecture up to 40 % higher energy harvest in PV installations can be achieved. The simple manufacturing process based on the SCHMID co-diffusion leads to best of class conversion costs.

SCHMID’s PERL Bifacial Cell Technology:

  • High efficiency by passivation on n-type mono material
  • Bifacial concept featuring over 30 % more energy yield
  • Just one temperature step for both phosphorus and boron deposition minimizes stress for the wafers
  • Lowest process times
  • Simple line configuration by proven equipment
  • Transparent back-sheet or glass on module rear side
  • Same cost of ownership as for PERC cells
Wet BenchAPCVDWet BenchAPCVDDiffusion
Texturing & polishingPSG formation BSFEdge isolation & etch back rear sideBSG formation emitterBoron & Phosphorus Co-diffusion


  • Efficiency potential of 25 %
  • Greatly reduced recombination
  • n-type for long durability
  • Bifacial technology for higher energy harvest
  • Smart process sequence with proven production equipment