2oldman wrote:
CA Traveler wrote:
In series with bypass diodes the voltage of a panel will be reduced say by 1/3 but the remaining 2/3 contributes to the overall voltage at the given amps.
The given amps of the entire string become whatever the amps of the shaded panel are. That's how series works.
Yes and the bypass diodes allow the series current to go around the cells not conducting due to shade. Each diode is in PARALLEL with groups of about 12 to 20 cells. See diagram above.
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.
All numbers nominal or rounded for clarity. This is the theory.
In reality the diodes are to protect the panel from damage more than provide shade tolerance.
Not much help with 12v panels in parallel.
