TOPCon stands for tunnel oxide passivated contact. It is an advanced crystalline silicon cell design, usually built on n-type wafers. Like heterojunction cells, it cuts recombination at the contacts. This gives a higher open-circuit voltage without lowering the fill factor. TOPCon is expected to become the dominant cell technology after 2025, and cell designs change about every six months. Because of this, the limited field data on TOPCon may not represent the modules being built today. The front contacts use a glass-frit metal paste that is fired through the passivation and the anti-reflective coating, the same method used on PERC cells. When the cells are laminated in EVA and moisture gets in, acetic acid from the EVA can corrode the front metallization and the interconnects. TOPCon has been reported to be even more sensitive to this than PERC. In damp-heat testing, power loss in TOPCon modules depended strongly on the encapsulant. Using TPO encapsulants helped limit the loss.
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subclass_ofc1 verified · fact Crystalline silicon PV
Described as an advanced c-Si cell architecture, typically on n-type wafers.
sec=2.6 h=0660da2db10dverified by: review-workflowverified on: 2026-10-24
related_toc2 drafted · lead Heterojunction cell
Both are advanced c-Si architectures that reach higher Voc by minimising contact recombination without reducing fill factor.
sec=2.6 h=0660da2db10dBoth use glass-frit front metal pastes fired through the passivation; TOPCon was reported more susceptible to front contact corrosion than PERC.
sec=2.6.1 h=b51dcb452e5bc4 drafted · lead Severe Metallization Corrosion
TOPCon front metal contacts and interconnects can corrode at the metal/Si interface, with sensitivity likely linked to high aluminium content in the front paste.
sec=2.6.1 h=b51dcb452e5breview note: support check: partial - Corrosion at metal/Si interface and high Al content link are stated, but 'severe' metallization corrosion as a named failure mode isn't explicitly stated; it's generic corrosion.
c5 verified · fact Acetic acid release
Acetic acid from EVA decomposition in the presence of moisture drives front contact corrosion; TOPCon cells showed a larger contact resistivity increase under acetic acid exposure than PERC and SHJ.
sec=2.6.1 h=b51dcb452e5bverified by: review-workflowverified on: 2026-10-24
c6 drafted · lead Alternative encapsulant material
Use of TPO encapsulants was shown to mitigate power loss in 1000 h damp heat.
sec=2.6.1 h=b51dcb452e5bc7 verified · fact Fill factor
Higher Voc is achieved without reducing fill factor.
sec=2.6 h=0660da2db10dverified by: review-workflowverified on: 2026-10-24
typical_power_lossc8 drafted · lead 4–65 PERCENT
Conditions: Maximum power loss (relative) of encapsulated TOPCon modules after 1000 h damp-heat testing across seven encapsulant/backsheet combinations; strongly dependent on encapsulation material (Sen et al.). PERC modules in the same study lost 1 to 2 %rel.
sec=2.6.1 h=b51dcb452e5brelated_to c2related_to c8