India’s solar manufacturing sector has undergone one of the most dramatic industrial transformations in the country’s post-independence economic history. From near-total import dependence just a few years ago, India is rapidly building a domestically integrated solar supply chain — spanning silicon wafers, solar cells, and solar modules — capable of supplying the country’s rapidly growing installed capacity and competing in global export markets.

Websol Energy System Ltd. stands at the heart of this transformation. As one of India’s oldest solar cell manufacturers — with a continuous manufacturing history dating to 1994 — Websol has evolved from a modest production unit to a 1.2 GW cell and 550 MW module manufacturing complex at Falta Special Economic Zone in West Bengal. With a ₹3,000 crore expansion to 5.2 GW underway, Websol’s growth story mirrors and drives the rise of Indian solar manufacturing.

This comprehensive guide explores the state of India’s solar manufacturing industry, the technology and processes behind a world-class module manufacturing line, and what Websol’s expansion means for developers, investors, and the broader renewable energy ecosystem.

The State of India Solar Manufacturing: 2026 Update

India’s solar manufacturing landscape has been fundamentally reshaped by a combination of policy interventions and market dynamics:

ALMM: The Demand-Side Catalyst

The Approved List of Models and Manufacturers (ALMM) maintained by MNRE restricts government-linked solar procurement to modules from listed manufacturers. This policy, which became increasingly enforced from 2023 onwards, has been the single most powerful demand-side driver for Indian solar manufacturing. By creating a guaranteed, protected market for ALMM-listed domestic manufacturers, it de-risked the massive capital investments required for GW-scale cell and module manufacturing.

Indian domestic module manufacturing capacity listed under ALMM crossed 144 GW by late 2026 — a 99% year-on-year increase — representing tens of thousands of crores of new manufacturing investment across India.

PLI: The Supply-Side Catalyst

The Production Linked Incentive (PLI) scheme for solar PV modules provided upfront investment rationale for manufacturers willing to build domestic capacity. While Websol’s expansion has been funded primarily through internal accruals and market-rate debt (without PLI support), the PLI scheme has catalysed industry-wide capacity additions that collectively strengthen the ecosystem.

Import Duties: Protecting Domestic Manufacturing

Basic Customs Duty of 40% on imported solar modules and 25% on solar cells creates a meaningful cost advantage for domestically manufactured products — particularly important as global (primarily Chinese) module prices have been at historic lows.

India’s 500 GW Target: The Market Pull

India’s target of 500 GW of renewable energy by 2030 creates sustained demand for solar cells and modules at a scale that justifies the massive capital investments required for GW-scale manufacturing. Domestic manufacturers like Websol are essential suppliers to this demand — particularly given DCR requirements for government scheme projects.

Websol’s Manufacturing Complex at Falta SEZ: An Overview

Falta Special Economic Zone, located approximately 50 km south of Kolkata in West Bengal, is home to Websol’s integrated solar manufacturing facility. The Falta site encompasses:

• 7 acres of manufacturing footprint
• 1.2 GW fully automated solar cell manufacturing capacity (Phase I: 600 MW + Phase II: 600 MW, commissioned October 2026)
• 550 MW solar module manufacturing line
• Quality control laboratories
• Effluent Treatment Plant
• Warehouse and logistics infrastructure

The facility’s location within the Falta SEZ provides:

• Duty-free import of manufacturing equipment and raw materials
• Streamlined export documentation
• Infrastructure support from SEZ authorities
• Favourable regulatory environment for manufacturing operations

Inside the Cell Manufacturing Line: How Monocrystalline Solar Cells Are Made

Websol’s cell manufacturing lines at Falta are fully automated, operating with minimal human intervention in the production process. The automation eliminates human handling errors, ensures process consistency, and enables the high throughput required for GW-scale manufacturing.

Stage 1: Incoming Wafer Inspection and Sorting

Premium M10 (182 mm × 182 mm) monocrystalline silicon wafers arrive from verified suppliers and pass through:

• Automatic optical inspection for surface defects, cracks, and contamination
• Electrical testing for resistivity (bulk doping level) and minority carrier lifetime
• Dimensional verification for thickness, total thickness variation, and bow

Only wafers meeting Websol’s incoming specifications enter the production line. Rejected wafers are returned to suppliers — ensuring no compromised material enters the cell.

Stage 2: Surface Texturisation

Wafers are immersed in heated alkaline solution (KOH or NaOH with additives) that selectively etches the silicon crystal planes to create a random pyramid surface texture. This textured surface dramatically reduces front-surface light reflection — from ~35% for polished silicon to under 3% — trapping photons that would otherwise be lost.

Stage 3: Emitter Diffusion

Wafers are loaded into a horizontal tube diffusion furnace with phosphorus oxychloride (POCl₃) gas at ~820°C. Phosphorus diffuses into the wafer surface, creating a thin n-type emitter layer (~200 nm) on the p-type wafer. This p-n junction is where photon-generated electron-hole pairs are separated to produce electrical current.

Stage 4: Phosphorous Silicate Glass (PSG) Removal

Diffusion deposits a glassy phosphosilicate layer on the wafer surface — this is removed by a brief HF acid dip, exposing clean silicon for subsequent processing.

Stage 5: Edge Isolation

Phosphorus diffuses around the wafer edges during the diffusion step, creating parasitic p-n junctions that would short-circuit front and rear contacts. Laser edge isolation removes these edge emitters, defining the active cell area precisely.

Stage 6: Anti-Reflection Coating (ARC)

Plasma-Enhanced Chemical Vapour Deposition (PECVD) deposits a silicon nitride (SiNₓ) layer on the front surface. This layer serves dual purposes:

• Optical: Refractive index graded to minimise reflection (responsible for the characteristic blue colour of monocrystalline cells)
• Passivation: Hydrogen atoms in the SiNₓ diffuse into the silicon bulk during a subsequent firing step, passivating defects and improving bulk carrier lifetime

Stage 7: PERC Rear Passivation (Critical Differentiator)

The PERC rear passivation is what distinguishes Websol’s cells from standard BSF designs:

1. Aluminium oxide (Al₂O₃) deposition by Atomic Layer Deposition (ALD) — the primary passivation layer, with strong field-effect passivation
2. Silicon nitride (SiNₓ) capping layer by PECVD — providing mechanical protection and additional passivation
3. Laser Contact Opening (LCO) — a pulsed laser ablates precise openings (typically 50–100 μm wide) through the passivation stack where rear aluminium contacts will be formed

Stage 8: Screen Printing Metallisation

Conductive silver and aluminium pastes are screen-printed onto front and rear surfaces using precision screen printers:

• Front: Fine silver fingers (30–35 μm wide) and busbars
• Rear: Aluminium paste in inter-LCO areas + silver for busbar pads

Stage 9: Co-Firing

The printed cell passes through a belt furnace at ~800°C for a few seconds. The rapid thermal cycle:

• Burns off organic binders in the paste
• Forms ohmic contacts between silver/aluminium and silicon
• Drives aluminium into the silicon at LCO openings to form the rear contacts
• Fires the front silver through the SiNₓ ARC to contact the emitter

Stage 10: Automated Testing and Binning

Every cell undergoes:

• I-V curve measurement under simulated AM1.5G illumination at STC
• Electroluminescence (EL) imaging to detect internal defects invisible to the eye
• Colour and visual inspection

Cells are automatically sorted into efficiency bins — ensuring matched cells within each module lot for optimal module performance.

Inside the Module Manufacturing Line: Cells to Finished Panels

Websol’s 550 MW module manufacturing line transforms individually tested solar cells into weatherproof, electrically complete solar modules rated for 25 years of outdoor operation.

Module Assembly Process

1. Cell Pre-Inspection Selected, binned cells are visually inspected and EL-tested before entering the module line — a second quality gate before assembly.
2. Tabbing and Stringing Automated tabber-stringer machines solder copper ribbon tabs to cell busbars and connect individual cells in series to form strings. Soldering parameters (temperature, pressure, speed) are continuously monitored and controlled.
3. Matrix Layout (Lay-Up) Cell strings are laid out on the front glass (3.2 mm low-iron tempered) in the precise cell matrix configuration. Front EVA encapsulant sheet and cell strings are positioned, then rear EVA and rear glass (for bifacial) or backsheet (for monofacial) are placed.
4. Lamination The glass-encapsulant-cell-encapsulant-glass stack enters a vacuum laminator. Under vacuum and controlled heat (typically 145–155°C), the EVA melts and cross-links, permanently bonding all layers into a monolithic laminate. Lamination parameters are tightly controlled to prevent voids, bubbles, or incomplete cross-linking.
5. Post-Lamination EL Inspection Every laminate undergoes electroluminescence imaging to detect any microcracks, solder failures, or interconnect defects introduced during the lamination process. Detected defects trigger rejection before further value is added.
6. Framing An anodised aluminium alloy frame is bonded to the laminate using structural silicone, providing mechanical rigidity and enabling standard mounting system compatibility.
7. Junction Box An IP68-rated junction box is adhered to the rear surface and electrically connected to the cell strings. Bypass diodes in the junction box protect against hotspot formation under partial shading.
8. Final Flash Testing Every completed module is tested at a solar simulator (flash tester) calibrated to IEC standards. The I-V curve at STC conditions is measured, and power output is recorded. Only modules meeting or exceeding their rated power are passed.
9. Visual and Mechanical Inspection Final inspection covers: glass surface, frame, junction box, connectors, labels, and overall appearance.
10. Packing and Dispatch Modules are packed in anti-static cartons, palletised, and prepared for dispatch to domestic or export destinations.

Websol’s Expansion: The Path to 5.2 GW

Websol’s approved expansion plans will transform the company’s manufacturing scale:

This expansion trajectory will make Websol one of India’s largest vertically integrated solar cell and module manufacturers — with a manufacturing platform capable of supplying the equivalent of 5 GW of solar power capacity per year.

Conclusion

India’s solar manufacturing story is one of the most important industrial narratives of our time — and Websol Energy System Ltd. has been writing it since 1994. From a small facility in Kolkata to a 7-acre, GW-scale manufacturing complex at Falta SEZ, Websol’s journey mirrors India’s own transition from solar import dependency to manufacturing self-reliance.

With 1.2 GW of automated Mono PERC cell capacity, 550 MW of module manufacturing, and an approved ₹3,000 crore expansion to 5.2 GW of TOPCon cell capacity by 2028, Websol is investing in India’s solar future with conviction. For developers, EPCs, and investors seeking a trusted, certified, domestically manufactured solar partner with the capacity to supply at scale — Websol is India’s answer.