In the economics of solar energy, every additional kilowatt-hour matters. That is precisely why bifacial solar cells — capable of generating electricity from both their front and rear surfaces — have rapidly become the technology of choice for utility-scale and commercial solar projects globally, and increasingly in India.

Websol Energy System Ltd. has been at the forefront of bifacial solar cell manufacturing in India, producing M10 Bifacial Mono PERC solar cells at its Falta SEZ facility in West Bengal. This guide explores the technology, advantages, real-world performance data, and installation considerations for bifacial solar cells — and explains why more project developers are specifying bifacial technology for their next solar installation.

What Are Bifacial Solar Cells?

A bifacial solar cell is a photovoltaic cell designed to capture sunlight from both the front (illuminated) side and the rear side. Traditional monofacial cells only generate electricity from photons striking the front surface — any reflected or diffuse light reaching the rear is wasted. Bifacial cells eliminate that waste.

The rear of a bifacial cell is designed to be semi-transparent or passivated rather than opaque, allowing light to reach the active silicon layer from below. This rear-side illumination — primarily from albedo (ground-reflected light), diffuse sky radiation, and inter-row reflected light — generates additional current above and beyond what the front surface alone produces.

The additional energy generated by the rear side, expressed as a percentage of front-side generation, is called the bifacial gain — typically ranging from 5% to 30% depending on:

• Ground surface albedo (reflectivity)
• Module tilt angle and mounting height
• Geographic latitude and sky diffuse fraction
• Tracker vs. fixed-tilt mounting

The Technology Architecture: How Websol Engineers Bifacial Solar Cells

Websol’s bifacial cells are built on the Mono PERC (Passivated Emitter and Rear Cell) architecture — the same technology that has driven monocrystalline solar efficiency above 23%. What makes Websol’s cells bifacial is the engineering of the rear surface:

Front Side (Standard PERC)

• Random pyramid texture surface for light trapping
• Silicon nitride (SiNₓ) anti-reflection coating
• Fine-line silver metallisation (front fingers + busbars)
• n-type emitter formed by phosphorus diffusion

Rear Side (Bifacial-Specific Design)

• Aluminium oxide (Al₂O₃) passivation layer — reduces surface recombination, enabling rear-side current generation
• Laser-opened rear contacts — precise openings through the passivation layer for aluminium fingers
• Rear silver/aluminium metallisation — transparent enough to allow light ingress while maintaining electrical contact
• No full-area aluminium BSF — unlike standard cells, which block rear light with a continuous aluminium layer

This design enables the rear surface to function as a genuine photoactive area — capturing reflected photons and converting them to electricity — while maintaining all the efficiency advantages of the PERC front-side architecture.

📌 Explore Websol’s M10 Bifacial Mono PERC Cell specifications: websolenergy.com/solar-cell

Bifacial Gain: What Does It Actually Mean for Energy Production?

Bifacial gain is the incremental energy yield from the rear side as a percentage of front-side generation. In practice:

For a 100 MW solar farm in Rajasthan on sandy terrain, a 15% bifacial gain translates to the equivalent of an additional 15 MW of generation capacity — without any additional land, additional modules, or additional inverters. The economics are transformative.

Indian solar auctions in 2024–25 saw discovered tariffs fall below ₹2 per kWh — a milestone driven in significant part by the adoption of high-efficiency bifacial modules that maximise energy yield per rupee of capital investment.

Bifacial Solar Modules: Construction and Design Considerations

Bifacial cells require bifacial modules — module construction that allows light to reach the rear of the cells. Websol’s bifacial modules use glass-glass construction:

• Front glass: 3.2 mm low-iron tempered glass with anti-reflection coating
• Front EVA (Ethylene Vinyl Acetate) encapsulant: UV-stable, transparent
• Cell string: M10 Bifacial Mono PERC cells, electrically interconnected
• Rear EVA encapsulant: Transparent, UV-stable
• Rear glass: 2.0–2.5 mm tempered glass (replacing the conventional opaque backsheet)

The glass-glass construction delivers multiple benefits beyond bifacial capability:

• Superior moisture and humidity barrier
• Better resistance to potential-induced degradation (PID)
• Higher mechanical strength (snow load, wind load)
• Longer operational lifetime (30+ years vs. 25 years for standard)
• Fire resistance Class C (improved safety for rooftop installations)

Installation Best Practices to Maximise Bifacial Solar Cell Performance

Getting the maximum value from bifacial solar cells requires installation practices that optimise rear-side light capture:

1. Mounting Height

Increasing the gap between the module rear and the ground from 30 cm to 100 cm can improve bifacial gain by 3–8 percentage points by allowing more ground area to contribute reflected light.

2. Ground Treatment

For fixed-tilt installations, using white gravel, reflective membranes, or light-coloured concrete under and around the module row spacing can boost ground albedo from ~20% to 50%+, significantly increasing bifacial gain.

3. Single-Axis Trackers

Horizontal single-axis trackers (HSATs) are highly synergistic with bifacial modules. By tilting modules to follow the sun, trackers increase front-side generation; simultaneously, the changing orientation exposes the rear to reflected ground light from different angles throughout the day, improving average bifacial gain.

4. Row Spacing Optimisation

Increased inter-row pitch reduces shading of the rear side, allowing more sky and ground-reflected diffuse light to reach rear cells. Energy yield simulation (with tools like PVsyst) should be used to optimise the pitch-to-bifacial-gain trade-off.

5. Frame-Free or Narrow-Frame Modules

Some bifacial module designs use frameless or narrow-frame construction to reduce rear-side self-shading — marginally improving bifacial gain in low-mounting-height conditions.

Websol’s Bifacial Solar Cells in Real-World Indian Projects

Websol’s M10 Bifacial Mono PERC cells and modules have been deployed across India’s diverse solar landscape:

Utility-Scale Ground Mount (Rajasthan) India’s solar heartland — 300+ days of sun per year, desert soil albedo of 25–35% — is ideal bifacial territory. Websol’s modules have contributed to projects in this region, where bifacial gains consistently exceed 15%.

Commercial Rooftop (Industrial Zones) Light-coloured concrete or metal roofing common in industrial parks provides albedo of 30–40% — enabling meaningful bifacial gains even in rooftop contexts, typically 8–15%.

PM-KUSUM Agricultural Solar Pumps Websol supplied 250 MW of Mono PERC DCR modules (including bifacial variants) to CRI Pumps for PM-KUSUM solar pump projects. Agricultural field albedo varies seasonally — greener crops produce higher albedo — making bifacial modules particularly well-suited for agri-solar applications.

📌 Related: DCR Cell and Module Compliance for Government Schemes →

Bifacial vs. Monofacial: Making the Right Choice

For most utility-scale and commercial ground-mount projects in India, bifacial technology offers a clear LCOE advantage. For constrained rooftop situations where mounting height and ground preparation cannot be optimised, the incremental benefit of bifacial is smaller but still positive.

Websol’s Commitment to Bifacial Technology: What’s Next

Websol has built bifacial capability into its manufacturing core — not as an add-on but as the standard architecture for M10 Mono PERC cells. The company’s expansion roadmap further deepens this commitment:

• 1.2 GW current cell capacity — fully bifacial capable
• TOPCon upgrade roadmap — N-type TOPCon cells deliver even higher bifacial factors (typically 85–90% vs. 75–80% for PERC), further boosting rear-side generation

4 GW expansion (Phases III & IV by 2028) — next-generation bifacial TOPCon at scale

Conclusion

Bifacial solar cells represent one of the most impactful advances in photovoltaic technology in the last decade — harvesting energy from light that conventional solar panels simply ignored. As India’s solar market matures and developers seek every possible LCOE advantage, bifacial technology has moved from premium option to mainstream standard.

Websol Energy System Ltd. has positioned itself as India’s leading bifacial solar cell manufacturer — combining advanced Mono PERC architecture, glass-glass module construction, and a 1.2 GW automated manufacturing platform to deliver bifacial solar products that meet international quality standards with full domestic compliance credentials.