How Do Bifacial Solar Panels Work?

In traditional (monofacial) solar panels, light energy that can’t be absorbed is reflected away, while the other side of the panel absorbs the light. Bifacial solar panels, on the other hand, feature solar cells on both sides of the panel. As a result, the panels are able to absorb light from both the front and rear. When it comes to the practicality of it, this implies a bifacial solar panel may absorb light reflected from the ground or another substance.

Can Bifacial Solar Panels Produce More Energy?

Bifacial solar panels can produce electricity at peak performance when placed near highly reflecting surfaces. Glass, sand, stone, and snow are some examples of such reflective surfaces. It’s still possible to increase electrical energy output by up to 30% even when the front of the solar cell is still absorbing most of the reflected light. The quantity of additional power output by bifacial solar cells will be influenced by the environment in which they are installed.

How Can You Increase The Output Of A Bifacial Module?

When it comes to solar radiation, the photovoltaic module's front receives direct sunlight, while the rear receives reflected sunlight from the ground and other nearby objects. This is also known as the albedo effect. When compared to monofacial panels, the bifacial performance is better because of the use of back radiation. As surfaces reflect light, the bifacial module may generate up to 35% more electricity from its backside. Four key elements influence the bifacial module efficiency. Height of the Module from the Ground For optimal bifacial gain, these bifacial solar modules should be installed at a distance of at least 20cm above the surrounding surface. As a side note, this rule only applies at less than one-metre distances. As you get higher, the bifacial gain decreases significantly. Tilt Angle of Module Like regular PV systems, larger tilt angles yield greater bifacial gains. Bifacial technology can benefit solar panels with a 10° inclination. strong>Distance between the Rows A wider row spacing allows for more light to reflect off the backsheet of the modules and reach the ground. The Albedo Effect: Game changer Most solar installers have never heard of this word before. On the basis of surface reflectivity, a brighter surface has a greater albedo light effect. In order to get more power out of a module, the albedo light value needs to be greater. For this reason, a white roof or snow-covered ground provides the best bifacial gain. Improvements are slightly smaller but still significant on a light grey/beige roof. The bifacial gain for asphalt or black coverings is small; however, it should be considered for all flat roofs .

Bifacial Solar Panels Guide - Solar Panels Network

Bifacial solar panels generate electricity from both the front and the rear of the panel. While conventional solar panels only capture sunlight hitting their front surface, bifacial panels also harvest light reflected from the ground and surrounding surfaces onto their back, increasing total energy output without needing more roof space.

In 2026, bifacial technology has become increasingly common in commercial and ground-mounted UK installations, and is beginning to appear in residential systems where the conditions favour it. This guide explains how bifacial panels work, when they make sense for UK properties, and what to look for when comparing them to standard panels.

Contents

1 Key Takeaways
2 How Bifacial Solar Panels Work
- 2.1 Albedo and Rear-Side Gain
3 Cell Technologies in Bifacial Panels
4 When Bifacial Panels Make Sense in the UK
5 Case Study: Agrivoltaic Pilot on a Cambridgeshire Farm
6 Expert Insights From Our Solar Panel Installers About Bifacial Panels
7 Frequently Asked Questions
8 Summing Up

Key Takeaways

Bifacial panels can generate 5-30% more electricity than equivalent monofacial panels, depending on installation conditions
The rear-side gain depends heavily on ground albedo, reflective surfaces like white gravel, concrete, or snow boost bifacial performance significantly
TOPCon and HJT cell technologies dominate the bifacial panel market in 2026, offering efficiency above 22%
Ground-mounted and flat-roof installations benefit most from bifacial panels; traditional pitched roof installations see smaller gains
UK agrivoltaic projects are using bifacial panels raised above crops, combining agricultural land use with electricity generation
MCS-certified installers can advise whether bifacial panels are the right choice for your specific installation

How Bifacial Solar Panels Work

Standard solar panels use an opaque backsheet that absorbs and reflects rather than transmits light. Bifacial panels replace this with either transparent glass (glass-glass construction) or a transparent polymer backsheet, exposing the rear of the solar cells to incoming reflected light.

The rear side of the panel generates electricity from albedo light, sunlight that has reflected off the ground, rooftop surface, or surrounding structures. The amount of additional energy this produces depends primarily on two factors: how much clearance exists between the panel and the surface below, and how reflective that surface is.

Albedo and Rear-Side Gain

Albedo is a measure of surface reflectivity, ranging from 0 (perfectly absorbing) to 1 (perfectly reflective). Common surface albedo values relevant to UK solar installations:

Fresh snow: 0.8-0.9, exceptionally high rear-side gain, though snow coverage in the UK is limited
White gravel or crushed stone: 0.35-0.45, excellent for ground-mounted systems
Light concrete: 0.25-0.35, good reflectivity for flat-roof commercial systems
Grass: 0.2-0.25, moderate gain, common in UK agrivoltaic and ground-mounted installations
Tarmac/asphalt: 0.05-0.10, low reflectivity, minimal bifacial benefit
Dark roofing membrane: 0.05-0.15, limited benefit for flat-roof systems with dark substrates

The typical bifacial gain in real-world UK conditions ranges from 5-15% for grass-based ground-mounted systems and 8-20% for white gravel or concrete surfaces. The upper end of the 30% gain figure seen in manufacturer specifications requires near-ideal albedo conditions such as snow cover or highly reflective white membranes, which are less common in the UK’s mild climate.

Cell Technologies in Bifacial Panels

Not all bifacial panels are equal. The cell technology used determines both the front-side efficiency and how much the rear side contributes.

TOPCon (Tunnel Oxide Passivated Contact)

TOPCon is the dominant bifacial technology in the mass market as of 2026. It uses a thin tunnel oxide layer at the rear contact to reduce recombination losses, enabling front-side efficiencies of 22-24%. TOPCon panels are inherently bifacial due to their rear architecture, and the technology scales well in manufacturing, keeping costs competitive with standard PERC panels.

Brands like Jinko Solar (Tiger Neo series), LONGi (Hi-MO 7), and Trina Solar (Vertex N) have made TOPCon their primary residential and commercial product. Bifacial TOPCon panels are available from most major installers in the UK in 2026 and carry standard 25-30 year product and performance warranties.

HJT (Heterojunction Technology)

HJT panels combine crystalline silicon with amorphous silicon layers on both sides, achieving front-side efficiencies of 24-26%, the highest of any mainstream bifacial technology. HJT also has the lowest temperature coefficient of any cell type (around -0.25%/°C versus -0.35%/°C for TOPCon), meaning HJT panels lose less output on hot summer days.

The rear-side contribution on HJT panels is particularly effective because the amorphous silicon layers on both surfaces are genuinely responsive to reflected diffuse light. REC Group, Panasonic (via OEM), and Meyer Burger produce leading HJT bifacial panels. HJT carries a price premium over TOPCon but is worth considering for installations where maximum output per square metre matters.

PERC Bifacial

PERC (Passivated Emitter Rear Cell) bifacial panels were the first widely available bifacial technology and are still sold, but they are being superseded by TOPCon in 2026. PERC bifacial panels offer front-side efficiency of 20-22% and rear-side gains of 5-15%, making them less competitive than newer N-type technologies for new installations.

When Bifacial Panels Make Sense in the UK

Bifacial panels are not a universal upgrade. Their advantage depends strongly on how the panels are installed and what’s beneath them.

Ground-Mounted Systems

Ground-mounted installations on frames elevated 0.5-1.5 metres above the ground are where bifacial panels deliver their most reliable gain. The clearance allows light to reach the rear surface across a wide angle, and the installer can control the ground surface by laying white gravel beneath the array to maximise albedo. For rural properties with space for a ground-mount, bifacial panels are a strong choice.

Flat Roofs with Tilt Frames

Commercial flat roof installations on tilt frames also benefit from bifacial panels, particularly where the roofing membrane is light-coloured or white. The tilt frame elevates panels at 10-15°, giving the rear surface exposure to reflected light. Some installers specify light-coloured ballast blocks or white membrane sections beneath bifacial arrays specifically to improve rear-side yield.

Pitched Roof Residential Systems

Standard pitched roof residential installations see the smallest bifacial benefit. Conventional on-roof mounting sits panels close to the tile surface, leaving very little clearance for light to reach the rear. The roofing tiles are also typically dark and non-reflective. In these conditions, bifacial panels may add only 2-5% over a standard monofacial panel of the same cell technology, which may not justify a price premium if one exists.

That said, if your installer is specifying TOPCon or HJT panels anyway (which is increasingly common in 2026), you may receive bifacial panels by default as they have become the standard format for N-type cells. In that case there’s no trade-off to consider.

Agrivoltaic Installations

One of the most interesting emerging applications in the UK is agrivoltaics: solar panels mounted on elevated frames above agricultural land, typically at 3-5 metres height, allowing crops or grazing to continue beneath. Bifacial panels are ideal for agrivoltaic systems because the additional height and the light-coloured or vegetated ground beneath delivers consistent rear-side gains. The UK government’s land use framework is increasingly supportive of agrivoltaic development as a dual land-use solution.

Case Study: Agrivoltaic Pilot on a Cambridgeshire Farm

Background

A farming operation near Cambridge installed a 50kWp agrivoltaic array in 2026 on 0.4 hectares of productive arable land. The landowner wanted to generate income from solar without taking land out of food production entirely. Bifacial TOPCon panels were specified because of their rear-side generation potential and the light-coloured compacted chalk soil beneath the array.

Project Overview

The system comprised 110 bifacial TOPCon panels mounted on a raised single-axis tracking structure at 3.2 metres clearance above ground. Winter wheat continued to grow beneath the array, with the panel spacing designed to allow sufficient light for crop growth. A 50kW three-phase string inverter connected the array to the grid under a G99 DNO approval, with the excess exported under a Power Purchase Agreement.

Implementation

The chalk soil beneath the array registered an albedo of approximately 0.35. Monitoring data from the first six months showed rear-side contribution of 11.2% above what a standard monofacial panel of equivalent front-side efficiency would have generated. Single-axis tracking added a further 18% gain over fixed-tilt, making the combined system significantly more productive per panel than a fixed ground-mount.

Results

First-year generation reached 51,400kWh against a projected 47,000kWh for an equivalent monofacial fixed-tilt system. The additional 4,400kWh was worth approximately £660 at the agreed PPA rate. The wheat crop beneath the array yielded 94% of the farm’s average for that field, with the partial shading providing some benefit during a dry summer spell by reducing crop water stress.

Expert Insights From Our Solar Panel Installers About Bifacial Panels

One of our senior solar panel installers with over 12 years of commercial and residential solar experience commented on bifacial panel selection:

“For standard residential pitched roofs, bifacial panels are often just what gets specified because that’s what the manufacturer makes in that cell technology, TOPCon is bifacial by design. The customer gets the technology without necessarily chasing the bifacial bonus. But for ground-mounts or flat roofs where we can control what goes beneath the array, we’ll actively optimise for rear-side gain. Laying a 50-metre roll of white geotextile beneath the array costs virtually nothing but can add a measurable percentage to annual generation.”

“The efficiency numbers from HJT panels are genuinely impressive, and the low temperature coefficient matters more than people realise in summer. But for most UK residential budgets, TOPCon bifacial hits the sweet spot of performance and cost in 2026.”

Frequently Asked Questions

Are bifacial solar panels worth it for UK homes?

For standard pitched roof installations, the bifacial advantage is modest, typically 2-5%, because there’s little clearance for light to reach the rear. However, since TOPCon panels (which are inherently bifacial) have become the standard cell technology in 2026, many installations include bifacial panels by default. For ground-mounted or flat-roof systems, bifacial panels offer a more meaningful 8-20% uplift over equivalent monofacial panels.

How much extra electricity do bifacial panels produce?

In UK conditions, bifacial gain typically ranges from 5-20% depending on installation type and ground surface. Ground-mounted systems on white gravel or light concrete see the highest gains. Pitched residential roofs see the least benefit. The 30% gains sometimes cited in manufacturer specs require near-ideal albedo conditions not typically found in UK installations.

What is bifacial gain and how is it calculated?

Bifacial gain is the percentage increase in energy yield from the rear side compared to a standard monofacial panel of equivalent front-side rating. It depends on the panel’s bifaciality factor (typically 70-90%), the ground albedo beneath the array, and the height clearance between the panel and the reflecting surface. Energy modelling software like PVsyst can estimate expected bifacial gain for a specific site.

What is the difference between TOPCon and HJT bifacial panels?

TOPCon offers front efficiencies of 22-24% and is the mainstream bifacial choice in 2026, combining strong performance with competitive pricing from manufacturers like Jinko, LONGi, and Trina. HJT reaches 24-26% efficiency and has a lower temperature coefficient (-0.25%/°C vs -0.35%/°C for TOPCon), meaning less output loss on hot days, but HJT carries a higher price premium. Both are excellent choices for UK installations.

Can bifacial panels be installed on a standard pitched roof?

Yes, bifacial panels can be mounted on pitched roofs using standard rail systems. However, the rear-side benefit is minimal in this configuration because the gap between the panel and roof tiles is too small for significant reflected light to reach the rear surface. The main reason to choose bifacial panels on a pitched roof in 2026 is that the best cell technologies (TOPCon, HJT) are produced in bifacial format as standard.

What ground surfaces increase bifacial panel output most?

White or light-coloured surfaces provide the best albedo. White gravel, crushed limestone, light concrete, and white geotextile membrane all significantly boost rear-side generation. Grass provides moderate albedo of 0.20-0.25. Dark surfaces like tarmac or black roofing membrane offer minimal bifacial benefit. Some installers lay white reflective material beneath ground-mounted bifacial arrays specifically to optimise rear-side yield.

Are bifacial solar panels more expensive?

In 2026, bifacial TOPCon panels are priced similarly to or only marginally above standard monofacial PERC panels, as TOPCon has become the dominant manufacturing technology. HJT bifacial panels carry a higher premium, typically 10-20% above TOPCon. For most UK residential installations, the cost difference is negligible when TOPCon panels are specified as standard.

What is agrivoltaics and how do bifacial panels fit in?

Agrivoltaics (also called agri-PV) involves installing solar panels on elevated frames above agricultural land, allowing farming to continue beneath. Bifacial panels are preferred for agrivoltaic systems because the greater clearance height and reflective ground surface (bare soil, grass, or crops) deliver consistent rear-side gains. The UK government is increasingly supportive of agrivoltaics as a dual land-use solution combining food and energy production.

Summing Up

Bifacial solar panels offer genuine generation advantages when installation conditions allow light to reach their rear surface. For ground-mounted and elevated flat-roof systems with reflective ground surfaces, the bifacial bonus of 10-20% is real and worth pursuing. For standard pitched residential roofs, the advantage is modest, but since the most efficient cell technologies available in 2026, TOPCon and HJT, are produced in bifacial format as standard, you’ll often get bifacial panels simply by specifying the best available technology. If you’re considering a ground-mounted system or have a flat commercial roof, talk to an MCS-certified installer about how to optimise the installation for rear-side gain.

Updated April 2026