> I saw a seller on ebay who claimed his cells were "brand new good
> condition" and in another paragraph: "cracked down the middle but you
> won't be able to tell when they're in a panel"

> $2 a watt is really cheap for a new solar panel. I wouldn't be all
> that surprised if the cells are cracked or damaged. Apparently it
> truly doesn't matter as long as the whole cell is there.

You don't need whole cells per se. What is required for cell material
to contribute is that it is electrically connected to a conductor. The
requirement is that there is a current path from all points on a cell
to a current pickup strip. If the cell has two (as is usually the
case) then having a crack between ends would at most produce only a
small difference in output (due to possibly longer current paths in
the PV material and conductors. In practice probably no noticeable
difference as reduced IR drop from lower currents per conductor would
largely offset the longer path.

Two cracks, so an area of cell is isolated, or a cell segment with one
conductor attached, and a crack which isolates a segment of cell, will
decrease output proportionally.

With multiple cells in series the panel output will be limited to
about the current output of the least capable cell.


   Russell McMahon
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