Bifacial modules have moved from a specialist option to a default line item on many Indian tenders. The IEA’s PVPS programme notes that bifacial cells, modules and systems are quickly taking market share from monofacial technology. The appeal is straightforward: a module that generates from both faces should produce more energy than one that generates from the front alone. The open question is how much more. In a modelling study across five Indian climate zones, published in Next Energy and reported by pv magazine in September 2026, bifacial gain ranged from 8.36% to 27.10% depending on location and ground surface. A range that wide tells developers and EPCs that the gain exists, and that most of what determines it is decided outside the module.
How Bifacial Modules Collect Light From Both Sides
Where a monofacial module relies on an opaque backsheet, a bifacial module uses cells that are active on both faces. Its rear side works with light reflected from the ground, from surrounding structures and from the diffuse sky. Most bifacial modules now use dual-glass construction, which suits rear-side collection and is valued separately for its durability.
The datasheet figure that matters is bifaciality, the ratio of rear-side to front-side performance under equal light. N-type TOPCon cells generally carry higher bifaciality than earlier PERC designs, which helps explain why TOPCon has become the standard bifacial platform. Bifaciality sets the ceiling for rear-side generation. Whether a project gets close to that ceiling is decided by its design.
Bifacial Gain Belongs to the Site
IEA PVPS defines bifacial gain as the additional share of total energy a bifacial system produces compared with a monofacial system of the same size and orientation. That definition places the gain in the system as a whole: the module, the structure, the ground and the climate all shape the result. IEA PVPS reports that single-axis tracker plants over typical natural ground, with albedo between 0.2 and 0.3, generally see gains below 10%. Figures well above that depend on conditions most commercial sites do not offer, which is why a gain quoted without its installation assumptions has limited value for a yield model.
Five Design Decisions That Set the Gain
Ground reflectivity sets the starting point, since the rear face can only use the light the surface returns. The Indian study found gain rising roughly in step with albedo, adding about 2.6 percentage points for every 0.10 increase. High-reflectance surfaces such as white paint and aluminium raised annual generation by around 13% to 16% compared with concrete. Dark roofing membranes and darker soils sit at the low end of that scale.
Mounting height decides how much of that reflected light reaches the rear cells, and how much ground the array shades beneath itself. NREL’s sensitivity study found that height above ground and albedo both directly affect bifacial performance. A reflective surface does little for a module mounted too close to it.
Row spacing trades rear-side light against land. NREL found that at an albedo of 21%, the centre module in a large array produced up to 7% less energy than a single bifacial module, because neighbouring rows restrict its view of the sky and shade the ground around it. Tighter layouts save land and give up part of the gain.
The mounting structure takes its own share. Rails, purlins, torque tubes and cable runs all block light from reaching the rear face. Researchers at the Technical University of Madrid, in field measurements reported by pv magazine, found that the tracker structure cut rear-side irradiance by 10.0% on one-in-portrait trackers. Structures designed with the rear face in mind recover part of that loss.
Tilt and tracking change how the rear face is lit across the day, so gain has to be modelled for the actual layout. Research from the Solar Energy Research Institute of Singapore, reported by PV Tech, found that bifacial modules on single-axis trackers delivered the lowest levelised cost of electricity across 93.1% of the land area studied. The study excluded land costs and assumed generous row spacing. In Indian markets where land is a significant cost, that advantage narrows.
What the Indian Data Shows
The Indian modelling study is most useful for what it shows about spread. Gains above 20% appeared only where favourable climate zones combined with highly reflective ground, while ordinary surfaces produced much lower results. Its setup also matters. The researchers modelled a 6 kW system mounted 1.5 m high with 5 m row spacing, a far more open arrangement than a densely packed multi-megawatt block. Read alongside NREL’s centre-module finding, the study supports a cautious reading: small or elevated test systems tend to overstate what full-size plants deliver. A study is a reference point for a project’s assumptions. It is not a forecast of the project’s yield.
Where the Economics Work, and Where They Thin Out
With mainstream manufacturing now built around bifacial TOPCon, the module itself is seldom where the real cost question sits. The more consequential decision is whether to invest in a taller structure, wider spacing or a lighter ground surface to capture more rear-side yield. In the Indian study, favourable high-albedo configurations reduced the levelised cost of electricity by 4% to 7%. Whether a specific project captures that depends on what those design changes cost on its site.
The economics are strongest on ground-mounted utility and large commercial projects with open land, elevated structures and adequate spacing, particularly over sandy, gravelled or naturally light ground. Carports, canopies and other elevated structures also perform well, since their design lets light reach the rear face from below. On land-constrained sites, the added yield per module can reduce the area needed to meet a target output.
The case weakens on low-tilt rooftops with dark membranes and dense rows, on structures that obstruct the rear face, and on dusty sites without a cleaning plan, where soiling cuts output from both faces. Bifacial modules can still be the right specification in these settings, particularly where pricing sits close to monofacial equivalents. The difference is that the financial model should carry a conservative gain assumption from the start.
What to Ask Before the Order Is Placed
Supplier conversations work best when they test the claims a yield model depends on. The first set of questions concerns the module itself: its bifaciality factor and how that figure was measured, and whether the construction is dual-glass and under what warranty terms. The second concerns the rating: the rear-side power figure, the rear irradiance it assumes, and the mounting height and row spacing behind any gain estimate the supplier provides. The third concerns documentation: whether the datasheets and test reports match the certifications the project requires, including ALMM listing. Put to solar panel suppliers in Gujarat or anywhere else, these questions quickly show whether a quoted gain reflects the planned layout or a best-case test.
The design team’s task is then to run an energy yield simulation with measured or realistic ground albedo and a conservative bifacial gain. A disciplined assumption protects project returns if site conditions underperform, and it gives lenders a figure they can defend. Comparing quotes from solar panel suppliers in Gujarat on modelled site yield, rather than on headline wattage, puts module selection on firmer ground.
Modelling the G12R DCR
GREW Solar’s G12R DCR is an N-type bifacial TOPCon module with 2 mm glass on both faces and a stated bifaciality of 80±5%. Its datasheet defines the bifacial rating at 135 W/m² of rear-side irradiance, which gives design teams a defined reference point for yield modelling. Project teams evaluating bifacial modules for utility, commercial or industrial sites can contact GREW Solar for the G12R DCR datasheet and the parameters needed to model it against their own layout.
As bifacial becomes the default specification across Indian projects, the gap between plants that capture the extra generation and those that do not will be decided at the layout stage. The teams that design the rear face as carefully as the front will be the ones that see it in their output.
