[TheSpiceIsLife]

From when I was reading more about solar cells I recall there being something about the distance from the conductor (the two stripes visible equidistant from the midline of the cell) being a problem especially with monocrystalline cells, which these appear to be. I think this was more a problem for cells that had the conductor fixed to the back of the cell.

Google image search for monocrystalline solar cell and you'll see they are all square. I had a brief go at searching for anything to back up my claim but lost interest.

I might simply be that the silicon ingot they are cut from is cast round, see this[1] picture and it's less wasteful to cut a square with chamfered corners than to cut a rectangle, which would necessitate an ingot with an elliptical cross section, which would probably be harder to cast due to uneven cooling, maybe.

1. http://www.tindosolar.com.au/learn-more/poly-vs-mono-crystal...

[extrapickles]

I'm not sure you can even make a mono crystalline ingot eliptical. The process heavily relies on spinning the ingot while pulling it out of a silicon puddle which results in the round shape.

[TheSpiceIsLife]

I've had a few moments recently where I've thought "how can it be I haven't thought to look this up on YouTube before now", and here we are.

I found this[1] video that explains how to grow a monocrystalline silicon ingot that weighs 440 pounds, and you're right it is spun as it's extracted from molten silicon.

1. https://www.youtube.com/watch?v=aWVywhzuHnQ