Among the most promising innovations in solar energy is the bifacial panel. Unlike traditional modules, which capture light only from the front, bifacial modules have two active faces: the front absorbs direct radiation and the rear uses light reflected by the ground, by water or by nearby surfaces.
How it works
The front face captures sunlight as usual, while the rear converts reflected radiation into extra energy. That extra depends on the albedo — how much light the surface below reflects. Over snow, desert sand, white membranes or light gravel, a bifacial module can deliver up to 30% more energy than a conventional one; over dark ground the gain is small.
Many bifacial models are built glass-glass (glass on both faces), which also improves durability and resistance to moisture, and is why manufacturers usually offer longer warranties for them.
Where bifacial pays off
- Ground-mounted solar plants, especially with high mounting and light-coloured ground.
- Single-axis trackers, where the rear stays exposed to reflected light all day.
- Solar carports and elevated structures over light pavement.
- Large commercial and industrial projects, where more energy per square metre shortens the payback.
Where it pays off less
On an ordinary residential roof, with the module mounted a few centimetres above the tiles, the rear face receives very little light and the bifacial gain shrinks to a few percent. It is not wrong to use a bifacial module there — prices have fallen and many models cost almost the same — but the extra generation should not be counted on in the sizing.
In short, the bifacial panel is now one of the main choices for medium and large projects. Where reflectivity is good, it is the smartest option on the market.
Expected bifacial gain by site
| Installation | Rear-side light | Typical extra energy |
|---|---|---|
| Residential roof, flush mount | Very low | A few percent |
| Ground mount over grass or soil | Moderate | ≈ 5–10% |
| Ground mount over light gravel or sand | High | ≈ 10–20% |
| Tracker over high-albedo ground or snow | Very high | Up to ≈ 30% |