PERC (Passivated Emitter and Rear Cell)
A silicon cell design that adds a passivating dielectric layer to the rear surface, reducing recombination and reflecting light back into the cell.
PERC was developed by Martin Green group at the University of New South Wales in the 1980s and became the mainstream industrial cell from about 2017 to 2023. A conventional aluminium back-surface-field cell loses efficiency because electrons and holes recombine at the full-area metal rear contact. PERC replaces most of that contact with a dielectric stack, typically aluminium oxide capped with silicon nitride, opened only at small laser-ablated points where the aluminium touches the silicon.
The rear stack does two things: it passivates surface defects, raising open-circuit voltage, and it acts as a mirror, sending long-wavelength light back for a second pass. Mass-production efficiencies rose from about 20% to 23–23.5%, near the practical ceiling of the architecture (ITRPV).
- Most PERC used p-type boron-doped wafers, which suffer light-induced degradation (LID) and light- and elevated-temperature-induced degradation (LeTID) of 1–3% unless mitigated.
- Bifacial PERC versions reach a bifaciality of about 70%.
- Power temperature coefficient about −0.34 to −0.37 %/°C.
From 2023 PERC lines have been converted or replaced by n-type TOPCon, which reuses much of the same equipment.
Related terms
All terms →- TOPCon
Tunnel Oxide Passivated Contact: an n-type silicon cell whose rear uses an ultra-thin oxide and doped polysilicon layer to extract current with minimal recombination.
- Heterojunction (HJT) solar cell
A cell that sandwiches an n-type crystalline silicon wafer between ultra-thin amorphous silicon layers, giving very high voltage and a low temperature coefficient.
- Solar cell
A semiconductor device, usually a doped silicon wafer with metal contacts, that converts sunlight directly into direct-current electricity via the photovoltaic effect.
- Degradation rate
The gradual annual loss of a PV module power output over its life, typically around 0.5% per year for crystalline silicon.
- Bifacial module
A PV module that collects light on both its front and rear faces, using a transparent back sheet or glass to harvest ground-reflected and diffuse light.