Mono PERC vs TOPCon vs Bifacial: Which Panel Is Best?
Efficiency, heat performance, degradation, price and subsidy eligibility compared side by side, and which panel suits which roof.
Rainbow Solar Energy Team
6 min read
Updated
In this article
Key takeaways
- Mono PERC is proven and good value, at about 20–21.5% efficiency.
- TOPCon gives about 22–23% efficiency, handles heat better and degrades slower, for a small premium.
- Bifacial panels also capture light from the back, adding about 5–15% on raised structures over light-coloured roofs.
- For the PM Surya Ghar subsidy, panels must be DCR (made with Indian cells), and DCR TOPCon is now widely available.
Panel technology has moved quickly. A few years ago almost every home system used Mono PERC panels; today TOPCon is becoming the new standard. Here's what the differences mean on a hot Indian rooftop.
Side-by-side comparison
| Mono PERC | TOPCon | Bifacial (PERC or TOPCon) | |
|---|---|---|---|
| Efficiency | 20 – 21.5% | 22 – 23%+ | Same as its cell type |
| Typical panel wattage | 530 – 550 W | 570 – 590 W | 540 – 590 W |
| Heat performance | Good (about −0.35%/°C) | Better (about −0.30%/°C) | Depends on cell type |
| Yearly degradation | ~0.55% | ~0.4% | Similar |
| Extra rear-side gain | – | – | +5 – 15% when raised |
| Price | Lowest | Slightly higher | Slightly higher + structure |
| Best for | Budget, large roofs | Small roofs, hot climates | Raised structures over light roofs |
Typical figures; they vary by manufacturer and model.
Mono PERC: the proven value choice
PERC (Passivated Emitter and Rear Cell) panels have powered millions of Indian rooftops. They're reliable, widely available as DCR panels, and the lowest cost per watt. If you have plenty of roof space and want the best price, they're still a solid choice.
TOPCon: more power from the same roof
TOPCon (Tunnel Oxide Passivated Contact) cells squeeze more power out of each panel and lose less output in heat, a real advantage on a 40°C Tamil Nadu terrace. They also tend to degrade slower, so the gap widens over 25 years. On a small roof, TOPCon can add a few hundred watts to the system you can fit.
Bifacial: light from both sides
Bifacial panels have glass on the back, so they also capture light reflected from the roof. The gain depends on height and how reflective the surface is: on a raised structure over a white-painted terrace, expect about 5–15% more units. Laid flat on a dark roof, the gain is small.
Subsidy check: PM Surya Ghar requires DCR panels (Domestic Content Requirement: made with Indian solar cells) from the approved ALMM list. Always confirm DCR in writing on your quote.
Which should you choose?
- Tight terrace? TOPCon, to fit more kW.
- Raised structure over a light roof? Bifacial TOPCon for the extra rear-side units.
- Large roof and tight budget? Mono PERC is still great value.
Space is often the deciding factor; check yours in how much roof space do you need, and see how panel choice affects price in the Tamil Nadu solar price guide.
Get the right panel for your roof
We compare PERC, TOPCon and bifacial options for your roof in one clear quote.
Written by our solar engineers and subsidy specialists, who design and install rooftop systems for homes, societies and businesses across Tamil Nadu. Figures are indicative and reviewed regularly; your free site survey gives exact numbers for your roof.
