smkettner wrote:
"Example:
Two 24v panels with 60 cells each (120 total cells)for a total of about 60 volts. There are 6 groups with 20 cells each. Each group produces 10 volts. (each cell produces about 1/2 volt and maybe 8 amps)
If all groups are producing power you get 60 volts 8 amps 480 watts.
One group is shaded you get 50 volts 8 amps 400 watts.
Two groups shaded 40 volts 8 amps 320 watts.
Actually it is a little less as each diode will lose 1/2 volt.
So with two groups shaded it is really 39 volts 8 amps 312 watts."
I agree. But, I note, as smkettner states that the total current is the current of the higher current, not the shaded cells! Also the voltage across the bypass diode of the shaded cell is about -.5V not +.5V. This could still charge if there is enough head room for the controller to work.
Salvo wrote:
"Taking this logic further, in a series configuration, the shaded panel t shat has 400W/m^2 irradiation will not conduct its bypass diodes. This string will have a total current about 2A, severely limiting production."
Not sure that is correct. The other cells are still producing their max current. Seems that the currents will add at the junction of the shaded cells and the not shaded cells. The current from the not shaded cells will forward bias the bypass diode so the short circuit current will be that of the higher current cells.?
