Most solar quotes tell you the wattage and the price. Very few tell you the panel is 2.4 metres long, which is the number that decides whether twelve of them fit on your roof or only ten.
Panel dimensions have changed more in the last five years than most buyers realise. A 2020 rooftop system used 330W panels about 1.7 metres long. A 2026 system uses 600W panels close to 2.4 metres. The wattage nearly doubled, the panel got longer, and the mounting structure, the lifting crew and the roof layout all changed with it.
This page gives the real measurements, in millimetres, for the panel sizes sold in India now.
The three standard sizes in 2026
Indian module manufacturing has settled on two wafer formats, M10R and G12R, and panels built from them come in predictable lengths. The figures below are from Atal Solar's published datasheets.
| Series | Power | Length | Width | Thickness | Weight |
| M10R 144 | Up to 600 Wp | 2278 mm | 1134 mm | 35 mm | 33 kg |
| G12R 132 | Up to 635 Wp | 2384 mm | 1134 mm | 35 mm | 34 kg |
| M10R 156 | Up to 650 Wp | 2466 mm | 1134 mm | 35 mm | 35 kg |
Three things are worth noticing. The width is identical across all three at 1134 mm, because it is set by how many cells sit across the module, not by its power. Only the length changes. And the weight moves very little, from 33 kg to 35 kg, so a roof that carries one will carry the others.
How much roof area each panel needs
Multiply length by width and you get the panel's footprint. Then add spacing, because panels cannot be laid edge to edge.
| Series | Panel area | Realistic area once installed |
| M10R 144, 600 Wp | 2.58 sq m | About 3.1 sq m |
| G12R 132, 635 Wp | 2.70 sq m | About 3.2 sq m |
| M10R 156, 650 Wp | 2.80 sq m | About 3.3 sq m |
The installed figure assumes roughly 20 per cent added for row spacing, walkways and edge clearance on a flat roof. On a sloped roof with panels sitting flush to the surface you can work closer to the bare panel area. On a flat roof with tilted mounting you need more, because each row shades the one behind it unless the rows are spaced apart.
Working out how many panels fit
The arithmetic is simple once you have the millimetres. A roof 10 m by 8 m is 80 sq m. Laid out for M10R 144 panels at about 3.1 sq m installed, that is 25 panels, or roughly 15 kW.
But the shape matters as much as the area. Ten metres divided by 2.278 m gives four panels along that run with 0.9 m left over, and that remainder is wasted unless the layout rotates. This is why installers measure the roof rather than its area: a long thin roof and a square roof of the same size fit different numbers of panels.
Why panels got longer
Cell size drove it. An M10R cell measures 182.2 by 183.75 mm. A G12R cell is 182.2 by 210 mm, wider in one direction. Put 132 of the wider cells into a module and you get 2384 mm of length. Put 156 of the narrower ones in and you get 2466 mm.
Manufacturers moved to larger cells because a bigger panel produces more power for roughly the same glass, frame, junction box and labour. The cost per watt falls. The trade off is that panels became heavier to lift and harder to fit on small roofs.
What else to check besides length and width
- Frame thickness. 35 mm is standard now, and your mounting clamps have to match it.
- Glass construction. Atal's modules are glass on glass, 2 mm front and 2 mm back, rather than glass and backsheet. That is what makes them bifacial, and it changes how weight sits on the structure.
- Weight per square metre. At 33 to 35 kg across roughly 2.6 to 2.8 sq m, these work out near 12.5 kg per sq m before mounting hardware. Older roofs should be checked by someone qualified.
- Cable length. 400 mm as standard, with longer cables available on request, which saves junction work on wide arrays.
Frequently asked questions
What is the standard solar panel size in India?
There is no single standard, but most modules sold in 2026 are between 2278 mm and 2466 mm long and 1134 mm wide. The width is consistent across the common formats; the length varies with cell count.
How much roof area do I need for a 5 kW system?
About eight panels of 650 Wp, which is roughly 26 sq m installed on a flat roof with spacing. Less if the roof is sloped and the panels sit flush against it.
How heavy is a solar panel?
Between 33 and 35 kg for current 600 to 650 Wp modules. Two people can carry one comfortably. One person cannot place one on a roof safely.
Are bigger panels always better?
For large flat roofs and ground mounts, usually yes, because fewer panels means less mounting and wiring per kilowatt. For small or awkward rooftops a shorter panel often fits the space better and produces more total power as a result.
