Quick answer: TOPCon and PERC are two ways of building the silicon cells inside a solar panel. TOPCon solar panels use n-type cells with an extra passivated contact on the back, which typically gives higher efficiency, less power loss in hot weather and lower warranted degradation than PERC. PERC is the older p-type design, and most large manufacturers are phasing it out.
This guide explains TOPCon vs PERC solar panels in plain terms for Australian homes. If you have compared solar quotes recently, you have probably seen "TOPCon", "N-type" or "PERC" on the panel datasheet. These labels describe the cell technology, and they affect how much power your system makes on a 38°C afternoon and 20 years from now.
What is the difference between TOPCon and PERC solar panels?
The main difference is how the back of the cell is built. PERC (Passivated Emitter and Rear Cell) adds a passivation layer to the rear of a p-type silicon cell, which bounces unused light back into the cell and cuts energy losses. TOPCon (Tunnel Oxide Passivated Contact) takes the idea further on n-type silicon, adding an ultra-thin oxide layer and a doped polysilicon layer at the rear contact.
- Different silicon. A PERC solar cell is usually made on boron-doped p-type silicon. Boron can combine with oxygen in the wafer and cause light-induced degradation (LID) early in a panel's life. N-type solar panels use phosphorus-doped silicon, which avoids most of this effect.
- Lower losses at the contacts. The tunnel oxide lets current pass while limiting the energy lost where metal contacts meet the silicon. The result is more power from the same panel area.
Both are monocrystalline technologies, so this is a separate question from monocrystalline vs polycrystalline panels. Most modern panels of either type also use half-cut cells.
Why most new solar panels are now TOPCon
TOPCon overtook PERC as the most produced cell technology in 2024. The 2026 edition reports that TOPCon held its lead through 2025, that n-type wafers reached around 82% of production, and that PERC's share fell to roughly 14%. The roadmap expects PERC to disappear from mainstream production within the next decade.
For homeowners, TOPCon is now the standard option from large manufacturers. JA Solar and Jinko Solar, two panel brands referenced on our website, both sell n-type ranges alongside older PERC models.
TOPCon vs PERC at a glance
The table compares two JA Solar ranges so the figures come from the same manufacturer. Check the model in your quote.
| Feature | PERC example (JA Solar Deep Blue 3.0, JAM54S30) | N-type example (JA Solar Deep Blue 4.0 Pro, JAM54D40) |
|---|---|---|
| Cell type | P-type PERC | N-type |
| Module efficiency | About 20.0% to 21.3% | About 22.0% to 23.8% |
| Temperature coefficient (Pmax) | -0.35%/°C | About -0.29% to -0.30%/°C |
| Performance warranty | 25 years, at least 84.8% output | 30 years, at least 87.4% output |
What the difference means on an Australian roof
Output on hot days
Every panel loses output as its cells heat up. The temperature coefficient tells you how much power is lost for each degree above the 25°C test temperature.
Say your panel cells reach 65°C on a summer afternoon, 40 degrees above test conditions. A PERC panel rated at -0.35%/°C would be producing about 14% below its rating at that moment. A TOPCon solar panel rated at -0.29%/°C would be about 11.6% below. The 2.4-point gap only applies in the hottest hours, but Australian summers bring plenty of them.
Degradation and warranties
The performance warranty sets the minimum output the manufacturer guarantees as panels age. In the example above, the PERC warranty promises at least 84.8% of rated output after 25 years. The TOPCon warranty allows 1% loss in year one and 0.40% a year after that, which works out to at least 89.4% at year 25.
On a 6.6kW solar system, that is a warranted floor of about 5.6kW for PERC versus 5.9kW for TOPCon at year 25. These are minimum guarantees, not forecasts. Real output also depends on shading, orientation, dust, heat and installation quality, which our solar performance guide covers.
Read the product warranty separately. It covers defects in the panel itself and is often much shorter than the performance warranty.
Roof space
Higher efficiency means more watts per square metre. On a small roof, that can help you fit a larger system, such as a 10kW solar system instead of 6.6kW.
Rear-side output
TOPCon cells suit bifacial designs, but on most pitched home roofs the rear-side gain is small, as our guide to bifacial solar panels for homes explains.
Are TOPCon solar panels reliable?
Generally yes, but TOPCon is newer and independent testing has found weak points in some products. That matters in Australia's strong UV and coastal humidity.
- UV sensitivity. UNSW researchers found UV-induced degradation in TOPCon cells happens mainly at the front surface. Their later work showed thicker aluminium oxide layers improve UV resilience.
- Damp heat. UNSW also identified failure modes in accelerated damp-heat testing of TOPCon modules that had not appeared in PERC panels.
- Improvement. Kiwa PVEL reported in 2025 that recent UV test results are starting to improve as manufacturers change their designs.
The manufacturer and model matter more than the TOPCon label. Ask about independent reliability testing and who handles warranty claims in Australia.
When could a PERC panel still make sense?
PERC may still suit you when:
- You are extending an existing PERC array and your installer needs electrically compatible panels.
- A quality PERC panel is heavily discounted and roof space is not a constraint.
Only panels on the Clean Energy Council's approved PV modules list at the date of installation can create small-scale technology certificates.
Checklist: questions to ask before choosing panels
A Solar Junction consultant can go through these with you on any quote.
- Is the panel TOPCon, PERC or another cell type?
- What is the temperature coefficient of Pmax on the datasheet?
- What output is warranted at year 25 or 30?
- How long is the product warranty, and who handles claims in Australia?
- Is the exact model number on the CEC approved modules list?
- Has the model passed independent reliability testing?
Key takeaways
- TOPCon uses n-type cells and typically beats PERC on efficiency, heat performance and warranted degradation.
- PERC is being phased out, but approved PERC models still qualify for STCs.
- Compare the exact model's datasheet, warranty and test record, not just the label.
