What is Bifaciality?
How well a bifacial panel generates from its rear side, shown as a percentage of its front-side output.
Quick Answer
Bifacial panels make most sense in the UK on flat roofs, ground mounts and over light-coloured or reflective surfaces, where rear-side light is meaningful. On a standard pitched roof with little reflected light reaching the back, the bifacial gain is small, so the higher cost is not always worth it. Several premium ranges (such as Aiko Nebular) offer bifacial options.
Fact-checked by John Rooney, Solar Energy Editor. Editorial policy
Bifaciality Explained
Bifaciality is the ratio of a bifacial panel's rear-side performance to its front-side performance, given as a percentage. A panel with 70 percent bifaciality produces up to 70 percent as much power from light hitting its back as from its front. The actual extra energy gained depends on how much light reflects onto the rear, which is driven by the surface beneath the panel (its albedo) and the mounting height. Bifacial gain in the real world is usually a few percent to around 10 percent, more over bright surfaces.
How Does Bifaciality Work in the UK?
Bifacial panels make most sense in the UK on flat roofs, ground mounts and over light-coloured or reflective surfaces, where rear-side light is meaningful. On a standard pitched roof with little reflected light reaching the back, the bifacial gain is small, so the higher cost is not always worth it. Several premium ranges (such as Aiko Nebular) offer bifacial options.
Frequently Asked Questions
What does bifaciality percentage mean?
Bifaciality is how much power a bifacial panel makes from its rear compared with its front, as a percentage. A 70 percent bifaciality panel can produce up to 70 percent as much from rear-side light as from the front, though the real gain depends on how much light reflects onto the back.
Are bifacial panels worth it in the UK?
They are worth it on flat roofs, ground mounts or over reflective surfaces, where meaningful light reaches the rear. On a normal pitched roof with little reflected light, the bifacial gain is small and the extra cost is often not justified.
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John Rooney is the founder of Solar Info and has been covering the UK solar energy market since 2023. He researches every battery and inverter brand against manufacturer datasheets, MCS and Ofgem data, and feedback from the MCS-certified installers in our directory before publishing.