What bifacial actually means
A conventional panel collects light on its front face only. A bifacial module has a transparent back, so reflected light from your roof surface generates power too.
Expected gains in Philippine conditions
| Mounting | Reflective surface | Typical bifacial gain |
|---|---|---|
| Flat white roof | High albedo | 8–12% |
| Light-colored metal roof | Medium | 5–8% |
| Dark roof membrane | Low | 2–4% |
N-Type cells also degrade slower — under 1% in year one, then about 0.4% per year — so year-20 output stays meaningfully higher than older P-Type panels.
The JA Solar 620W advantage
At 22.6% module efficiency, fewer panels cover the same load — critical on space-constrained Filipino rooftops where every square meter counts.