21 October 2026
TOPCon versus bifacial is a comparison that cannot be settled, because the two words describe different parts of the same module. TOPCon is a cell technology. Bifacial is a module construction. A single panel can be both, and most TOPCon modules sold in India in 2026 are glass-to-glass bifacial.
The two decisions actually in front of you are these: TOPCon cells or Mono PERC cells, and bifacial construction or monofacial. This guide takes them one at a time, shows what each is worth in energy and rupees, and ends with the sites where bifacial earns nothing at all.
| TOPCon | Bifacial | |
| What it describes | The cell: N-type silicon with a tunnel oxide passivated contact | The module: glass on both faces, so the rear also generates |
| The real alternative | Mono PERC cells (P-type) | Monofacial modules with a polymer backsheet |
| What it changes | Efficiency, degradation, heat behaviour | How much light the module can reach |
| Measured as | Module efficiency, 20 to 24% | Bifaciality factor, 65 to 80% |
| Can it be the other? | Yes, TOPCon modules are usually bifacial | Yes, bifacial modules can use PERC or TOPCon cells |
So when a supplier asks whether you want "TOPCon or bifacial", they are either simplifying or they do not know their own product. The right question is which of the four combinations below suits the site.
| Module type | Module efficiency | Relative price per watt | Where it belongs |
| Mono PERC monofacial | 20 to 21% | Lowest | Tight budgets, flush rooftop mounting, plenty of space |
| Mono PERC bifacial | 20 to 21% front side | Low to middle | Ground-mount on a budget, where upfront capital rules |
| TOPCon monofacial | 22 to 23% | Middle | Dark or flush rooftops where rear gain is impossible |
| TOPCon bifacial | 23 to 24% front side | Highest | Elevated mounts, light surfaces, ground-mount, large C&I roofs |
This is the decision that applies to every project, on every site, regardless of mounting.
| Specification | Mono PERC | N-type TOPCon |
| Module efficiency | 20 to 21% | 23 to 24% |
| First-year degradation | About 2% | About 1% |
| Annual degradation thereafter | 0.55% or so | 0.4% or so |
| Temperature coefficient | Around -0.35%/°C | Around -0.30%/°C |
| Bifaciality, when built bifacial | 65 to 70% | 80% or so |
| Energy over 25 years | Baseline | 8 to 12% more |
Independent technology data backs this up: the Fraunhofer ISE Photovoltaics Report tracks how N-type cell architectures have taken production share from PERC, and the US Department of Energy's efficiency primer explains why module efficiency always reads lower than cell efficiency.
The price gap has nearly closed. Non-DCR Mono PERC has been trading at roughly Rs 13.8 per watt and non-DCR TOPCon at about Rs 14.2, a difference of under half a rupee for 8 to 12% more lifetime energy. On that arithmetic TOPCon wins for most buyers, and the exceptions are specific: a project with unlimited roof area and a hard capital ceiling, or a scheme that forces DCR modules where the domestic-content premium dominates every other consideration.
Note one thing in that table. TOPCon's bifaciality of about 80%, against 65 to 70% for PERC, means the two decisions are not independent. If you intend to go bifacial, TOPCon cells convert the rear-side light considerably better, so the combination is worth more than either change alone. Our TOPCon solar panel guide covers the cell structure, and the Mono PERC guide makes the case for the older technology where it still holds.
Bifacial modules generate from the rear face as well as the front. How much they add is decided almost entirely by what sits beneath them, because the rear can only collect light that the ground reflects back up. That reflectivity is called albedo.
| Surface under the modules | Albedo | Realistic rear-side gain |
| White membrane or painted white roof | 60 to 80% | 20 to 25% |
| Desert sand, light gravel | 35 to 45% | 15 to 20% |
| Concrete | 25 to 35% | 10 to 15% |
| Grass or soil | 15 to 25% | 5 to 10% |
| Dark membrane or bitumen roof | 5 to 15% | 2 to 5% |
Mounting geometry decides whether any of that reaches the cells. Three things matter: height above the surface, row spacing, and whether the rear is blocked by structure. A module 1.5 to 2 m off the ground on a light surface collects well. The same module clamped 150 mm above a dark roof collects almost nothing, and a rail or tray running across the back of the module shades the rear cells no matter what the ground does. The TOPCon bifacial guide works through albedo, mounting height and row spacing with the numbers, and the bifacial solar panels guide explains the construction and the bifaciality factor.
Four situations, all common, where paying the bifacial premium is money gone:
In all four cases, TOPCon monofacial modules are the better buy. You keep the cell technology that pays for itself through efficiency and degradation, and you stop paying for glass and a bifaciality rating the site cannot use.
Take a 100 kW factory rooftop as the worked example. The cell decision, PERC to TOPCon, adds roughly Rs 40,000 to module cost at Rs 0.4 per watt, and returns 8 to 12% more energy for 25 years. On a system generating about 1.4 lakh units a year, that is 11,000 to 17,000 extra units annually, worth Rs 88,000 to Rs 1.36 lakh a year at an industrial tariff of Rs 8 per unit. It pays back in months.
The construction decision is site-dependent and that is the whole point. On an elevated mount over a white roof, the bifacial premium of Rs 1 to 1.5 per watt buys 20 to 25% more energy and pays back within two to three years. On a flush dark roof it buys 2 to 5%, which never pays back. Same module, same price, completely different answer, decided by the surface underneath.
For projects at megawatt scale, where these multipliers compound across the whole capex, our breakdown of the cost of a 1 MW solar plant sets out the numbers, and the bifacial solar panel price guide covers current per-watt rates.
Credence Solar manufactures both constructions at its 2.2 GW Rajkot plant: TOPCon bifacial up to 745 Wp with a bifaciality factor of 80±5%, and TOPCon monofacial from 580 W upward. Every figure in this guide appears on the product datasheets.
TOPCon and bifacial are not rivals. TOPCon is the cell decision and it favours TOPCon for nearly everyone in 2026, because the price gap has fallen under half a rupee per watt while the energy gap stayed at 8 to 12%. Bifacial is the construction decision and it depends entirely on the site: excellent on elevated mounts over light surfaces, worthless on a flush dark roof. Decide the cell on economics, the construction on geometry, and ignore any quote that treats them as one choice.
For specifications on either construction, or bulk pricing, get in touch.
Neither, because they are not alternatives. TOPCon describes the cell technology and bifacial describes the module construction, so a panel can be both, and most TOPCon modules sold in India are bifacial. The decisions to make are TOPCon or Mono PERC cells, and bifacial or monofacial construction.
Yes, and that combination is the most common high-end module in India in 2026. A TOPCon bifacial module uses N-type tunnel oxide passivated contact cells between two sheets of glass. TOPCon cells also convert rear-side light better than PERC, with a bifaciality factor around 80% against 65 to 70%.
Between 2% and 25%, decided by what sits under the modules and how far off it they are mounted. Elevated mounts over white membrane or sand reach 20 to 25%. Concrete gives 10 to 15%, grass 5 to 10%, and modules clamped flush to a dark roof gain almost nothing.
Usually not. Most residential installations clamp modules close and parallel to the roof, which leaves no path for reflected light to reach the rear face. Unless the system uses an elevated or tilted frame over a light-coloured terrace, TOPCon monofacial modules give you the cell advantage without paying for unusable rear glass.
In most cases yes. TOPCon adds 3 percentage points of module efficiency, roughly halves the degradation rate, runs cooler, and converts rear-side light better with a bifaciality of about 80% against 65 to 70%. The module price difference is under half a rupee per watt for non-DCR modules.
80±5% is the current standard for N-type TOPCon bifacial modules, while PERC bifacial modules sit at 65 to 70%. The figure is the rear-side efficiency as a share of the front, measured under IEC test conditions. If a datasheet does not state it with a tolerance, treat the bifacial claim as unverified.
