# Solar Panel Types: Mono PERC vs TOPCon vs Bifacial

> Which solar panel technology is best for an Indore roof? Mono PERC, TOPCon, bifacial and polycrystalline compared on efficiency, heat performance, degradation and price.

Canonical: https://geniussolarservices.com/learn/solar-panel-types-mono-perc-topcon-bifacial

Most rooftop systems in India now use monocrystalline modules. Mono PERC is the proven, cost-effective standard (about 20.5–21.5% module efficiency). TOPCon is the newer n-type technology with higher efficiency (about 21.5–23%), a better temperature coefficient for hot Indore summers and lower first-year degradation. Bifacial modules also capture light reflected onto their back and gain most on elevated structures over light-coloured roofs. Polycrystalline modules are largely obsolete for new rooftops.

- **Mono PERC eff.:** ≈20.5–21.5%
- **TOPCon eff.:** ≈21.5–23%
- **Bifacial gain:** ≈5–15% (site-dependent)
- **Typical size:** 540–590 W


## The quick comparison

| | 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](/services/elevated-solar-structure-indore) 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](/learn/dcr-vs-non-dcr-solar-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.


Updated: 2026-09-29

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**Genius Solar Services** · G-1, Swarna Palace, Plot No. 1108, Scheme No. 114, Part 1, Vijay Nagar, Near MP Gramin Bank, Indore, Madhya Pradesh 452010 · Phone +91 98267 12299, +91 78288 12299, 0731 400 4499 · geniussolarservices@gmail.com · Mon – Sat · 10:00 am – 7:00 pm
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