[raverbashing]

Yes, it would be interesting to know if there's an advantage of connecting so many cells in series

Most systems limit themselves to something like 48v as you said (I think 48v is the threshold of "being dangerous")

[kragen]

Higher voltage means lower current and thus lower voltage loss, and lower percentage losses for the same voltage loss, so you don’t need lots of copper.

[raverbashing]

Yes, but you're throwing it into an inverter, and it's not like you're carrying it too far. High voltages also present problems in itself (isolation, etc)

Now, on a second thought, maybe it's more efficient to do 400VDC to 120VAC/240VAC (don't know the exact values)

[kragen]

DC-DC buck converters may be a little simpler and more efficient than boost converters, I don't really know.