Solar PV · Glossary
p-Type PERC
The previous-generation solar cell technology using p-type silicon and Passivated Emitter Rear Cell architecture, now being phased out by n-type TOPCon.
p-Type PERC (Passivated Emitter Rear Cell) was the dominant solar technology from around 2017 to 2024. Efficiency typically tops out at 21%, with panel power 380-415W. P-type silicon is more prone to light-induced degradation (LID) and light-and-elevated-temperature-induced degradation (LeTID), so first-year degradation is typically 2-3% and annual thereafter 0.5-0.55%.
If you have a solar install from 2017-2023, the panels are almost certainly PERC, and they will continue to perform well for 25+ years. There is no urgent reason to replace them. For new installs in 2026, however, n-type TOPCon is now cheaper per watt and degrades less, so PERC is no longer specified.
If you are extending an older PERC array, mixing PERC with TOPCon on the same string is technically OK but suboptimal — better to install the new panels on a separate MPPT input or with a separate inverter. See our solar installation page.