Mono PERC and half-cut solar panels
Mono PERC was the standard rooftop panel in India for years, and half-cut is a way of wiring cells that most modern panels now use. The two terms often appear together on a quote. Here is what each one means for your roof.
Updated 27 September 2026
Mono: the silicon
A monocrystalline cell is cut from a single, continuous crystal of silicon, which gives the electrons a clean path and makes the cell more efficient than a polycrystalline one, made from many small crystals melted together. Polycrystalline panels have largely left the market; almost every panel quoted for a rooftop today is mono.
PERC: the layer on the back
PERC stands for Passivated Emitter and Rear Cell. A reflective layer on the back of the cell bounces light that went straight through back into the silicon, where some of it is turned into power. For years this was the step that made a good panel.
On UTL’s own panels, mono PERC lists between 19.52% (the 390 W) and 20.10% (the 240 W).
Half-cut: how the cells are wired
Half-cut says nothing about the type of cell. Each cell has been cut into two, and the panel is wired as two halves side by side, which improves two things.
- Each half-cell carries half the current, and power lost as heat in the wiring falls sharply as current falls.
- The two halves of the panel work independently, so a shadow from a water tank or a parapet across one half leaves the other half producing.
Half-cut is now used on most large panels, PERC and TOPCon alike. UTL’s 735 W half-cut module is one; its 590 W TOPCon half-cut bifacial is another.
Mono PERC against TOPCon
| Mono PERC | TOPCon | |
|---|---|---|
| Efficiency, UTL panels | 19.52% to 20.10% | 21.28% to 23.32% |
| In summer heat | Loses more output as it heats | Loses less; see the TOPCon page |
| Price per watt | Usually lower | Usually higher |
| Suits | Small and off-grid jobs, pumps, roofs with room to spare | Home and commercial rooftops, small or crowded roofs |
Which to choose
For a new home or business rooftop, TOPCon is usually worth the difference. For a small off-grid system or a solar water pump, where roof space is not the limit, mono PERC does the job for less. Either way, if you want the PM Surya Ghar subsidy, the panels must be DCR; see DCR and non-DCR panels.
For the full picture, which panel technology is best now sets all of them side by side.
Questions we are asked
What does mono PERC mean?
Mono means the cells are cut from a single crystal of silicon, which makes them more efficient than older polycrystalline cells. PERC, Passivated Emitter and Rear Cell, adds a layer on the back of the cell that reflects unused light back through it for a second chance.
What is a half-cut solar panel?
A panel whose cells are cut in half, so there are twice as many, each carrying half the current. Lower current means less power lost as heat in the wiring, and the panel is split into two halves that work independently, so shade on one half hurts the output less.
Is mono PERC or TOPCon better?
TOPCon, on efficiency and in heat. UTL's TOPCon panels list 21.3% to 23.3% efficiency against 19.5% to 20.2% on its mono PERC panels. Mono PERC can still cost less per watt, which suits some jobs.