Why do monocrystalline solar cells have rounded/cropped edges?

[cemtu]

Homework Statement

Why do monocrystalline solar cells have rounded/cropped edges? And why do solar cells need to be square-shaped in general?

Relevant Equations

No equations

There were circular solar cells 30 years ago. Why do we have square-shaped solar cells now? Why square now?

 

[Mayhem]

Rectangles pack better than circles. Seems that individual cells also assume a rectangular shape. .

 

[hmmm27]

Way I understand it, the outside of the boule tends towards polycrystalline formation (mono is preferable).