Calculate bifacial gain for your PV system
Use this tool to quantify the extra energy yield of bifacial solar panels based on front irradiance, ground albedo, bifaciality factor, rear shading, tilt, and system size.
Inputs
Annual plane-of-array irradiance on the front side.
Nameplate DC capacity of the PV system.
Grass ≈ 0.20 · Concrete ≈ 0.30 · White gravel ≈ 0.50 · Snow ≈ 0.80
Rear-to-front efficiency ratio (typical 0.70 – 0.95).
Fraction of rear-side blocked by racking, rows, or objects.
Steeper tilt reduces rear view factor to the ground.
Higher mounting improves rear irradiance collection.
Results
Annual front yield
—
kWh/year (front only)
Rear-side yield
—
kWh/year (extra from bifacial)
Total annual yield
—
kWh/year (front + rear)
Bifacial gain
—
Extra yield from rear side (%)
How bifacial gain is calculated
The model estimates rear-side irradiance using ground albedo, panel tilt, mounting height, and a rear-view factor. It then applies the bifaciality factor and subtracts rear shading to produce an extra rear yield:
rear_view_factor = f(tilt, height)
rear_irradiance = front_irradiance × albedo × rear_view_factor
rear_yield_kWh_per_kWp = rear_irradiance × bifaciality × (1 − shading) / 1000
bifacial_gain_% = rear_yield / front_yield × 100
Results are indicative. Real-world bifacial gain depends on row spacing, ground cover uniformity, seasonal albedo changes, and system design.
Frequently asked questions
How much extra energy do bifacial solar panels produce? ▾
Bifacial solar panels typically produce 5% to 25% more energy than comparable monofacial panels, depending on the ground albedo, panel height, tilt, and rear-side shading. Highly reflective surfaces such as white gravel, concrete, or snow can push bifacial gain above 20%, while grass or dark soil usually yields 5–10%.
What is the bifaciality factor and how is it used in gain calculations? ▾
The bifaciality factor is the ratio of rear-side efficiency to front-side efficiency of a bifacial solar module, typically ranging from 70% to 95%. In gain calculations, the rear-side energy contribution is computed as: rear irradiance × bifaciality factor. A higher bifaciality factor directly increases the extra yield from bifacial panels.
How does ground albedo affect bifacial solar panel performance? ▾
Ground albedo measures how much sunlight the surface reflects back toward the rear of the panel. Typical values range from 0.2 for grass to over 0.8 for fresh snow. Higher albedo delivers more rear-side irradiance and significantly increases bifacial gain, which is why reflective ballasts, white membranes, and elevated mounting are recommended.