Bifacial Solar Panels: How Much Extra Energy Do They Really Produce?

Bifacial modules look like an obvious improvement: capture light on both sides and generate more electricity. The physics is sound. The financial case depends almost entirely on what sits beneath the panel — which is why bifacial is standard on some projects and pointless on others.

What makes a module bifacial

A conventional module has an opaque backsheet. Light reaching the rear is absorbed or blocked; the cells only work from the front.

A bifacial module replaces that with a transparent rear layer — usually a second sheet of glass, producing a glass-glass construction. Cells are designed to respond to light from both directions, and rear contacts are arranged so they do not block incoming light.

The glass-glass build brings a secondary benefit worth noting: better resistance to moisture ingress and mechanical stress, which is why bifacial modules often carry longer warranties and lower stated degradation rates than their monofacial equivalents.

Albedo decides everything

The rear face generates from reflected light, so the question is how much light the ground bounces back up.

That property is albedo — the fraction of incoming light a surface reflects.

• Fresh snow: very high, reflecting most incoming light.
• Light sand and desert terrain: high.
• Concrete and light gravel: moderate to high.
• Dry grass and bare soil: low to moderate.
• Dark soil, asphalt, vegetation: low.

The consequence is direct. A bifacial array over white gravel might deliver a substantial gain. The identical array over dark earth delivers very little. Same module, same sunlight, materially different output.

This is why bifacial deployment clusters in deserts and snowy regions — and why Gulf projects, sited on reflective sand, were early and enthusiastic adopters.

Geometry matters as much as albedo

Reflected light must physically reach the rear surface. Installation geometry therefore drives a large share of the gain.

Mounting height. A module close to the ground shades the area beneath it and blocks the reflected light it needs. Raising the array lets more reflected light reach the rear face. Higher mounting costs more in steel and foundations, which is a real trade-off rather than a free gain.

Row spacing. Tighter rows shade the ground between them, reducing available reflected light. Wider spacing improves rear-side gain but uses more land.

Mounting structure design. Torque tubes, rails and cable management all cast shadows on the rear face. Bifacial-optimised structures minimise rear obstruction — a genuine design discipline, not a marketing claim.

Tilt. Steeper tilt generally exposes more rear surface to reflected light.

Why trackers and bifacial pair so well

Single-axis trackers and bifacial modules are frequently deployed together, and the combination is more than additive.

Trackers keep modules elevated and rotating through the day. In early morning and late afternoon, when panels tilt steeply, the rear face gains substantial exposure to reflected light. The two technologies complement each other, which is why utility-scale projects in high-albedo regions so often use both. We cover the tracker side in our explainer on solar trackers.

Where bifacial does not belong

Flush-mounted rooftop systems. A module mounted parallel and close to a roof surface has its rear face pointing at an adjacent opaque surface. Almost no reflected light reaches it. The premium buys essentially nothing — though the glass-glass durability may still justify it on its own terms.

Dark, vegetated ground with low albedo, where the gain rarely justifies the additional cost and mounting requirements.

Projects where land is severely constrained, since capturing bifacial gain often means wider row spacing, which uses more land per megawatt.

Modelling it honestly

Bifacial gain is genuinely harder to model than conventional output, because it depends on site-specific albedo, geometry, seasonal ground conditions and row shading.

Two failure modes recur:

• Optimistic albedo assumptions — using a laboratory or best-case figure rather than the measured, seasonally varying reality of the site.
• Ignoring structural shading on the rear face, which can remove a substantial share of the theoretical gain.

A serious proposal states the assumed albedo, its source, and the modelled bifacial gain separately from front-side production. If those figures are not broken out, the estimate cannot be checked — the same discipline we recommend for soiling assumptions on desert projects.

The bottom line

Bifacial modules are close to standard for utility-scale projects on reflective ground with elevated mounting, particularly alongside trackers. They are largely pointless on flush rooftops. The module is only half the system — the ground beneath it and the steel holding it up determine whether the premium returns anything.

Follow the technologies changing project design

Bifacial, trackers and cell architecture together determine how much energy a site actually delivers.

• Read the solar energy desk for technology and project analysis.
• Explore our Middle East coverage, where high-albedo sites make bifacial particularly relevant.
• Subscribe to The Energy Edit — free, independent reporting. Start here.

Module and mounting suppliers: reach engineers specifying these systems. Explore partnership.