The quick comparison
| Item | Polycrystalline | Mono PERC | TOPCon (n-type) | Bifacial (PERC or TOPCon) |
|---|---|---|---|---|
| Module efficiency | ~16–18% | ~20.5–21.5% | ~21.5–23% | Same front + rear gain |
| Temperature coefficient | ~-0.40%/°C | ~-0.35%/°C | ~-0.30%/°C | Depends on cell |
| First-year degradation | ~2.5% | ~1.5–2% | ~1% | Depends on cell |
| Look | Blue, speckled | Uniform black-blue | Uniform black-blue | Often glass-glass |
| Best for | Budget legacy | Most rooftops | Hot climates, max output per roof | Elevated structures |
Figures are typical ranges from manufacturer datasheets; always check the specific module's datasheet.
Why "half-cut" matters
Most modern modules use half-cut cells: each cell is laser-cut in two, so each half carries half the current. Resistive losses fall, hotspots run cooler, and a shaded corner affects a smaller part of the module. The 144-cell modules you see on Indore roofs are 72 full cells cut in half.
PERC vs TOPCon in Indore's heat
Cells on a rooftop in May can hit 60–65°C. With a temperature coefficient of -0.35%/°C, a PERC module loses about 12–14% of its rated power at that temperature; a TOPCon module at -0.30%/°C loses about 10–12%. Over a summer, that difference adds up — which is why TOPCon is increasingly popular for Indian rooftops.
Bifacial modules and elevated structures
Bifacial modules have a transparent back (glass or clear backsheet) and generate from light reflected off the surface below. The gain depends on height and how reflective the roof is:
| Setup | Typical rear-side gain |
|---|---|
| Flush on dark roof | ~0–3% |
| Low tilt on grey concrete | ~3–6% |
| Elevated 2 m+ over white/light roof | ~6–12% |
Our elevated structures are a natural fit for bifacial modules.
DCR vs non-DCR
This is about where the cells are made, not the technology. Subsidised home systems under PM Surya Ghar must use DCR (Domestic Content Requirement) modules with Indian-made cells. See DCR vs non-DCR panels.
What we recommend
- Homes with subsidy: DCR mono PERC or DCR TOPCon, 540–580 W class.
- Elevated structures: consider bifacial DCR modules.
- Businesses without subsidy: non-DCR TOPCon usually gives the best cost per unit generated.