Tuesday, Oct 06, 2015 at 02:16
So you guys really wanna know....ok here goes AFAIK.
As you're probably aware of, a PV cell is made up of a semi conductive p and n region resembling a diode.
An electric field of variable intensity exists where these two regions come together (called the depletion zone).
This field acts as a charge separator.
Incoming light creates extra charge carriers on both sides of the depletion zone.
A buildup of charge carriers weakens the field.
Provided there's an external current path the charge buildup is moderate, leaving the field intact.
Charge diffusion through the depletion zone remains small.
What happens in open circuit?
There is no external current path, charge on both sides of the depletion zone keeps building until the diode becomes forward biased.
At a voltage of about 0.6V the cell basically short circuits itself.
That's why a 36 cell solar panel has an open circuit voltage of 36*0.6V=21.6V (temp dependent).
I'm not an expert though, just knowing enough that I know I don't know everything about this :)
Like drift current caused by minority carrier recombination.
In open circuit, the field becomes weak enough for the resulting diffusion current to balance the opposing drift current so that the net current is zero - you asked!
Cheers
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