Two technologies are shaping the future of solar cell manufacturing in India — Mono PERC and TOPCon. Both are high-efficiency, N-type and P-type respectively, and both are being deployed at scale across utility, commercial, and industrial projects. But they are meaningfully different in efficiency, cost, degradation behaviour, and long-term energy yield.

If you are an EPC contractor, developer, or large-scale energy buyer currently evaluating module technology for your next Indian solar project, this guide gives you the technical and commercial picture you need to make the right decision.

A Quick Primer: What Are PERC and TOPCon?

Mono PERC (Passivated Emitter and Rear Cell) is currently the dominant solar cell technology globally and in India. It is a P-type monocrystalline technology where the rear surface of the silicon wafer is passivated — meaning a dielectric layer is added to reduce energy loss at the rear. This design improves light capture and raises efficiency compared to older BSF (Back Surface Field) cells.

Websol’s solar cells are manufactured using the Mono PERC architecture — specifically the M10 Bifacial Mono-PERC design that powers many of India’s commercial and utility solar installations.

TOPCon (Tunnel Oxide Passivated Contact) is an N-type technology that adds an ultra-thin silicon oxide layer and a doped polysilicon film on the rear side. This structure dramatically reduces recombination losses — the phenomenon where electron-hole pairs combine before generating electricity — resulting in higher efficiency and lower degradation.

TOPCon is often positioned as the “next generation” after PERC. Several major Indian manufacturers have begun production, and global TOPCon shipments have risen sharply since 2023.

Efficiency Comparison

This is where TOPCon clearly leads.

In practical terms, a TOPCon module produces 3–5% more electricity than a comparable PERC module of the same physical size. For a 10 MW project, that difference can mean 300–500 MWh of additional annual generation — depending on irradiance.

However, efficiency is only one input into the energy yield equation. Degradation rate, temperature coefficient, and low-light performance matter significantly over a 25-year project life.

Degradation and Long-Term Performance

One of TOPCon’s strongest arguments is lower Light-Induced Degradation (LID).

PERC cells, being P-type, are susceptible to LID — a temporary drop in power output that occurs within the first hours of sun exposure due to boron-oxygen defect formation. High-quality PERC modules from reputable manufacturers typically show Year 1 degradation of 1.5–2% before stabilising.

TOPCon’s N-type architecture inherently avoids the boron-oxygen defect problem, resulting in much lower LID. TOPCon modules from leading manufacturers show Year 1 degradation of 0.5–1%, with annual degradation thereafter below 0.4%.

Over 25 years, this compounding advantage is significant. A TOPCon module may retain 88–90% of its rated output after 25 years, compared to 82–85% for a standard PERC module.

For Indian investors calculating energy yield for PPA agreements or SECI tenders, the lower degradation can meaningfully improve IRR projections.

Temperature Coefficient: Critical for Indian Conditions

India’s solar project sites — Rajasthan, Gujarat, Andhra Pradesh, Tamil Nadu — regularly see ambient temperatures exceeding 40°C. Module temperatures at noon can reach 65–75°C.

Both technologies suffer power output loss as temperature rises, but TOPCon typically has a slightly better (lower absolute value) temperature coefficient:

• Mono PERC: −0.34% to −0.38% / °C
• TOPCon: −0.28% to −0.32% / °C

In practical terms, on a hot Indian afternoon, a TOPCon module will outperform a PERC module of nominally equal wattage. For high-irradiance, high-temperature Indian sites, this advantage accumulates meaningfully over a year.

Cost Comparison

This is where PERC continues to hold its ground in India.

As of mid-2026, TOPCon modules command a price premium of ₹2–5 per Wp over comparable PERC modules, depending on supplier and volume. For a 50 MW project:

• PERC modules: ~50,000,000 Wp × ₹22/Wp = ₹110 crore
• TOPCon modules: ~50,000,000 Wp × ₹26/Wp = ₹130 crore

That’s a ₹20 crore premium for 50 MW. The question is whether the additional lifetime energy yield justifies the higher upfront cost — and whether your project’s tariff structure allows for that calculation.

For government-linked tenders — particularly those under PM Surya Ghar Yojana or SECI bids where tariff ceilings are tight — PERC’s cost advantage frequently wins.

For C&I (Commercial & Industrial) projects with captive consumption and long-term self-financing, TOPCon’s lifetime yield advantage can justify the premium.

Bifaciality: Both Technologies Benefit

Both Mono PERC and TOPCon are available in bifacial module configurations, where rear-side light absorption adds 5–25% additional energy yield depending on installation conditions.

TOPCon’s bifaciality factor tends to be slightly higher (typically 80–85%) compared to PERC (70–80%), meaning TOPCon bifacial modules capture a marginally greater share of rear-side reflected light.

In high-albedo environments — white gravel, reflective roofing, or elevated tracker systems — this difference becomes more pronounced.

ALMM and DCR Compliance: Both Qualify

For government-linked procurement in India, DCR (Domestic Content Requirement) compliance requires cells to be manufactured domestically. Both PERC and TOPCon cells are manufactured in India by ALMM-listed producers, including Websol.

If your project falls under a DCR mandate, verify that your chosen module’s cells are sourced from an MNRE-approved Indian manufacturer — regardless of whether they are PERC or TOPCon.

Module Format Compatibility

Both technologies are available in M10 (182mm) and G12 (210mm) wafer formats. The technology choice and the wafer format choice are separate decisions.

Websol currently produces M10 Bifacial Mono-PERC solar cells that are used in high-wattage solar modules delivering 525–570 Wp output.

Websol’s Position on Technology Evolution

Websol Energy System has been manufacturing solar cells since 1994 — making it one of India’s earliest solar cell producers. The company’s M10 Bifacial Mono-PERC cells are currently the product of choice for Indian EPCs seeking reliable, ALMM-listed, domestically manufactured cells.

The Falta SEZ manufacturing facility is built for evolution — as TOPCon transitions from premium to mainstream in the Indian market, Websol’s infrastructure and process expertise positions it well for the shift.

Decision Framework: Which Should You Choose?

Use this framework to guide your technology decision:

Choose Mono PERC (Bifacial) if:

• Your project is bid under a tight tariff ceiling (SECI, state DISCOM tenders)
• You need DCR-compliant cells at competitive pricing
• Project size is below 50 MW with moderate IRR requirements
• Logistics, inverter compatibility, and proven yield data matter more than marginal efficiency gains

Choose TOPCon if:

• You are developing a C&I or IPP project with long-term PPA at premium tariff
• Site temperatures routinely exceed 42°C
• 25-year energy yield modelling is central to your financial model
• You have flexibility on module pricing and can absorb a ₹3–5/Wp premium