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What is the meaning of this croped part? Why do they crop it, rather than let it be full square?

PhysicsSolvesAll
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the monocrystalline cells are thinly sliced off cylindrically-grown single crystals that look like logs. Each wafer thus produced is hence a circular disc. To make the resulting solar cell function properly, its active area must be square so the rounded edges of the wafer get sawn off so the wafers can be packed together as closely as possible during bulk processing. The chamfered corners are left.

niels nielsen
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  • Why do they cut the edges? Why don't they leave the sharp edges be? I really do not understand please explain. Why isn't it square like polycrystalline cells? Do they remain big this way? Would it be smaller if it was cut perfectly square? – PhysicsSolvesAll May 21 '21 at 17:36
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    I suspect what niels is implying at is that there is one cell per wafer/slice from a round ingot (not many cells per slice as might be the case for integrated circuits), in which case a single square with rounded corners could use up more of the circular area on an the cross section of a round ingot while still be square enough to tessellate. – DKNguyen May 21 '21 at 18:37
  • @DKNguyen, yes that is the point. – niels nielsen May 22 '21 at 00:47
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This question might be a bit old, but I think it is not too late to share knowledge to the world. You might be a bit confused by the first answer, but here I got some visual illustrations for you to understand why and how mono crystalline photovoltaic cells often has that chamfered or cut corner look.

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Mono crystalline cells are cut from a single crystal grown in a cylindrical log shape, which has a circular cross section. It is easy to think that manufacturers might cut corners for cost cutting but that's not what is happening here. Before cut into wafers, the cylindrical crystal log is chamfered/cropped into square log, just at the right spot so that the cells could be arranged compact enough to produce maximum possible energy without wasting too much space and also there won't be too much wasted material if cropped into perfect square. If left uncropped, having circular disc shaped cells in a panel not only weird but also wastes too much space for lesser efficiency. I'm sure there might be other reasons I didn't mention but this is what I know so far.

For your curiosity, there are actually some mono crystalline cells that doesn't have this chamfered look, if they're made of bigger diameter crystal log, of course, but for some reason they're quite rare.

Here's an illustration of the manufacturing process of poly crystalline for reference and how they had that perfect squared cut without any chamfer.

All illustrations thanks to AE-Solar

Poly crystalline manufacturing process

Yudhi G.
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