Light from both sides
A bifacial module has a glass or transparent back sheet and cells that generate from light reaching the rear face. 55.3% of tracked modules are now built this way - it has stopped being a premium feature and become the default construction for anything mounted off a roof surface.
The number to read is the bifaciality factor: the share of front-side output the rear face produces under equal light. 6,024 panels declare one, and the median is 80%. That is not free extra energy - the rear face only sees whatever the ground or roof reflects back, so the gain in a real array is a fraction of the factor and depends entirely on the surface below.
What the distribution shows
Declared factors cluster hard at 70% and 80%, which are datasheet conventions as much as measurements. 784 modules claim 85% or better, and those are the ones where the construction genuinely differs rather than the wording.
Heterojunction and back-contact cells are symmetric by construction, so their rear faces collect more of what reaches them. PERC rear faces are partly blocked by the aluminium back surface field, which is why they sit lower.
Highest declared bifaciality
Ground mounts over light surfaces, carports, east-west flat roofs and anything with clearance behind the array: the rear face has something to collect and the gain is real.
Flush-mounted on a pitched roof: the rear face sees the underlay from 40 mm away and the factor is worth almost nothing. The extra glass still costs weight, which the power density page prices.
By manufacturer
This ranks what manufacturers declare, not what independent testing found. The clustering at round numbers is a good reason to treat a two-point difference between brands as noise.
Catalogues under 20 panels are marked in amber: a brand with one dual-glass product line leads this table easily.
Manufacturer insightsHow these numbers are built
Every figure comes from a manufacturer datasheet ingested into the panel database. Nothing is modelled, estimated, or supplied by a brand outside its own published specification.
Aggregates recompute as new panels arrive. A panel that does not declare a value is left out of that average rather than filled in, so every figure here is backed by modules that actually publish it.
No paid placements, and no figure here reads which shops pay us a commission. Each power rating counts as the module it is. Bifacial datasheets that quote one module at several assumed rear-side gains are counted once, on their front-side rating.