Shade on One Panel in a 2 String Array?

dancour

What happens to the total output when only 1 of 2 strings becomes shaded?

Picture 2 horizontal rows - each a string.

A panel in the lower row (string) becomes shaded.

What are the output results?

Is there a better way to wire the strings?

Thanks

BB.

Re: Shade on One Panel in a 2 String Array?

Depends on the size of the string and what it is attached too...

If these where 2x panel strings (Vmp~35 volts) charging a 24 volt battery bank, one panel shaded will cut that string's output to near zero (100% loss).

If this was a 10+x panel string panel (~300 VDC) running on a Grid Tied Inverter, you might lose the rough equivalent of 10% for a 10 panel string (or 1/number of panels per string) of that string's output (in the best of conditions).

In general, if the voltage of parallel strings or the current of series strings is within 10% of each other, then the loss of shading one is pretty much linear. However, this also depends on the load (i.e, the operating voltage and current range must be greater than the minimum requirements of the load).

In the end, shading, clouds, utility wires, etc. going across solar PV panels is bad news and should be avoided whenever possible.

-Bill