Bifacial Solar Panels: How They Work & Are They Worth It?
Bifacial panels generate electricity from both the front and rear face. In the right install, the bonus from reflected light adds 5–25% to annual output — but for most UK pitched-roof homes, they offer little advantage over standard monofacial panels.
Quick Answer
Bifacial solar panels capture sunlight on both sides of the panel, adding 5–25% extra annual output ("bifacial gain") depending on mounting type and surface reflectivity. They cost £0.40–£0.80 per watt more than equivalent monofacial panels — roughly £80–£200 extra per panel. They are most valuable on ground-mount, carport, pergola, and flat-roof installations where light can reach the rear face. For standard pitched-roof homes where the back of the panel sits against the roof, bifacial gain is minimal (typically 1–3%) and the extra cost is rarely justified.
How bifacial solar panels work
A traditional (monofacial) solar panel uses a single layer of solar cells with an opaque white or black backsheet behind them. Light hits the front, the cells convert it, and any light that misses the cells is absorbed or reflected away by the backsheet.
A bifacial panel replaces the backsheet with a transparent material — usually a second sheet of glass or a clear polymer. The solar cells are visible from behind, and they are designed to convert light from either face. Any sunlight reflected off the surface beneath the panel (concrete, gravel, snow, white roof membrane) hits the rear cells and produces additional electricity.
Most bifacial panels use TOPCon or HJT (heterojunction) cell technology, which is naturally bifacial. Older PERC cells can be made bifacial with design tweaks but typically have a lower “bifaciality factor” (the ratio of rear-face efficiency to front-face efficiency, usually 70–90%).
How much extra power? Bifacial gain by install type
The extra output from bifacial panels — called bifacial gain — depends on three things: the surface beneath the panel (its albedo), the clearance between the panel and the surface, and the tilt.
| Mounting type | Typical bifacial gain | Why |
|---|---|---|
| Pitched roof (close-coupled) | 1–3% | Rear face nearly touches roof tiles; little reflected light |
| Flat roof (ballasted, white membrane) | 5–12% | White EPDM/TPO reflects 70–80% of light to rear face |
| Ground mount (grass, soil) | 5–10% | Soil albedo ~20%; gain depends on tilt and clearance |
| Ground mount (gravel, concrete) | 10–15% | Higher albedo (~30%) gives more rear-face generation |
| Carport / pergola | 10–20% | Clear gap below + reflective surface (concrete, snow) |
| Solar farm with tracker + snow | 15–25% | Snow reflects 80–90%; trackers maximise both faces |
UK reality check. Most UK homes have close-coupled pitched-roof installations, where bifacial gain is just 1–3%. The extra panel cost rarely pays back. Bifacials only make economic sense for flat roofs with reflective membranes, carports, and ground-mount projects.
How much do bifacial solar panels cost?
In 2026, bifacial panels cost roughly £0.40–£0.80 more per watt than equivalent monofacial panels — that is £80–£200 extra per 400–500W panel. Some Tier-1 brands (LONGi, JA Solar, Trina) have narrowed this gap to under £0.30/W as bifacial volumes scale up.
| System size | Monofacial cost | Bifacial cost | Cost premium |
|---|---|---|---|
| 4kW residential (10 panels) | £6,500–£8,000 | £7,500–£9,500 | £1,000–£1,500 |
| 6kW residential (15 panels) | £8,500–£11,000 | £10,000–£13,000 | £1,500–£2,000 |
| 10kW commercial (25 panels) | £10,000–£14,000 | £12,000–£17,000 | £2,000–£3,000 |
| 50kW ground mount | £40,000–£55,000 | £48,000–£65,000 | £8,000–£10,000 |
The premium needs to be offset by the bifacial gain. On a ground-mount with 12% gain, the extra cost typically pays back in 4–6 years and the panels still have 20+ years of bonus output ahead. On a pitched roof with 2% gain, the premium often never pays back.
Best uses for bifacial panels in the UK
Solar carports & pergolas
Ideal use case — the rear face is fully exposed to reflected light from concrete, paving, or grass. 10–20% gain typical.
Flat commercial roofs (white membrane)
TPO and white EPDM membranes reflect 70–80% of light. With ballasted 10° mounts, bifacial gain of 5–12% is achievable.
Solar farms & ground mounts
Most large UK solar farms now specify bifacial. Combined with single-axis trackers, gains of 15–25% are realistic.
Solar fences & vertical mounts
Vertical bifacial fences capture morning sun on one face and evening sun on the other, flattening the generation curve through the day.
Agrivoltaics
Bifacial panels mounted high above crops or grazing land let livestock and machinery pass underneath while harvesting reflected light.
Standard pitched roofs
Not recommended. The rear face has almost no exposure. Stick to high-efficiency monofacial Tier-1 panels and put the savings into a battery or larger array.
Leading bifacial solar panel brands
LONGi Hi-MO 7
Up to 590W bifacial, 22.8% efficiency, 80% bifaciality, 25-year warranty. Tier 1, widely used in UK solar farms.
JA Solar DeepBlue 4.0
Bifacial TOPCon up to 625W, 23.2% efficiency, 30-year warranty option. Strong UK distribution.
Trina Vertex N
Bifacial n-type up to 615W, 22.5% efficiency, 30-year warranty. Popular in commercial flat-roof installs.
Jinko Tiger Neo
N-type TOPCon bifacial up to 625W, 23.2% efficiency, 30-year warranty. Globally largest bifacial shipper.
Canadian Solar TOPHiKu7
Bifacial TOPCon up to 700W (commercial), 22.8% efficiency. Targeted at large ground-mount.
REC Alpha Pure-RX
Smaller-format heterojunction bifacial up to 470W, 22.6% efficiency. UK premium-residential niche.
Bifacial Solar Panels: FAQ
Are bifacial solar panels worth it in the UK?
For ground-mount, carport, and flat-roof installs, yes — the extra 5–25% generation usually justifies the £0.40–£0.80/W premium. For standard pitched-roof homes (where the rear face is close-coupled to the tiles), bifacial gain drops to 1–3% and the extra cost rarely pays back. Choose monofacial for typical residential roofs.
How much more do bifacial panels cost?
In 2026, bifacial panels cost roughly £0.40–£0.80 per watt more than equivalent monofacial panels — about £80–£200 extra per 400–500W panel. The premium has narrowed sharply in the past three years as production volumes have scaled.
What is bifacial gain?
Bifacial gain is the percentage of extra annual energy a bifacial panel produces compared to an identical monofacial panel in the same install. It ranges from 1–3% (pitched roofs) to 25% (solar farms with trackers and high-albedo surfaces).
Do bifacial panels work in cloudy UK weather?
Yes. Bifacial panels respond to diffuse light just like monofacial panels. In overcast conditions, a small bifacial gain still occurs because diffuse light is omnidirectional and reaches both faces.
Are bifacial panels heavier than monofacial?
Yes — replacing the lightweight backsheet with a second glass layer adds 5–8kg per panel. Glass-glass bifacial panels weigh 28–32kg vs 22–25kg for glass-backsheet monofacial. Check roof load capacity before specifying.
Can I use bifacial panels on a standard pitched roof?
You can, but the rear face will be almost fully shaded by the roof. Bifacial gain drops to 1–3%, which rarely justifies the cost premium. Spend the same money on a higher-power monofacial panel or a battery instead.
What is the bifaciality factor?
The ratio of rear-face efficiency to front-face efficiency, expressed as a percentage. Modern TOPCon and HJT panels typically have a bifaciality factor of 80–90%; older PERC bifacials are 70–80%. A higher number means more useful rear-face generation.
Do bifacial panels need special inverters?
No. Standard string and microinverters handle bifacial panels perfectly. Just be aware that the inverter should be sized for the front-face peak output plus a margin for bifacial gain — under-sizing the inverter will clip generation in good conditions.
Related Guides
Solar Panel Types
Monocrystalline, polycrystalline, thin film, bifacial, and IBC panels compared.
Best Solar Panels
Top 5 solar panel systems ranked for UK homes.
Panel Brands
Best solar panel brands available in the UK.
Ground Mounted Solar
Costs, planning permission, and installation for garden solar panels.
Sources
- NREL — Bifacial Photovoltaics — nrel.gov
- IEA PVPS — Bifacial PV technology report — iea-pvps.org
- Solar Energy UK — Industry data — solarenergyuk.org
Last updated: May 2026.
Fact-checked by John Rooney, Solar Energy Editor. Editorial policy
John Rooney is the founder of Solar Info and has been covering the UK solar energy market since 2023. He fact-checks all content against official MCS and Ofgem data and maintains relationships with MCS-certified installers across the UK.
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