Mono PERC, TOPCon or bifacial? Solar panel types explained

Quotations often list panel technologies by name. Here is what they mean in practice.

Mono PERC

Monocrystalline cells with a passivated rear layer that reflects unused light back into the cell. A proven, cost-effective technology that has been the standard for rooftop systems for several years.

TOPCon

Tunnel Oxide Passivated Contact cells, a newer n-type technology. They usually offer higher efficiency, lower degradation over time and slightly better performance in heat than PERC, which matters in Gujarat's summers. Many manufacturers have moved their main lines to TOPCon.

Bifacial

Panels that capture light on both sides. The rear side picks up light reflected from the surface below, so they gain most on elevated structures, white or light-coloured roofs and ground-mount plants. On a dark roof with panels mounted close to the surface, the extra gain is small.

What to look for on any panel

• Wattage and efficiency: higher efficiency means more power from the same roof area.
• Temperature coefficient: a smaller figure means less power loss on hot days.
• Performance warranty: typically 25-30 years, with a stated yearly degradation.
• ALMM listing and BIS certification: required for subsidised residential systems in India.

We list the panel type, model and warranty in every proposal. See the brands we install.

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