Serial vs Parallel Solar Panel Shading
I was asked if a post in another thread if this "Serial is actually better for shading (than parallel) if that is a concern for you." was a typo. It is not a typo but panel shading is not always under...
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There is a ton of errors in this post.
...panel shading is not always understood on this board......
-You are the one not understanding
...the same shading scenario for parallel panels means that reduced panel voltage does not contribute ...
-wrong, it does the same as for panels in series-it produces reduced output
...at high noon if I had 7 section shaded the panel output would be 20V at 8A or 160W/14.8V=10A bulk charging...
-wrong, it would be (20V-7*0.6V)*8A=15.8V*8A=126.4W/14.8V=8.54A of bulk charging at 14.8V
...assuming 8A the output would be 8A*70V=560W for the serial panels. For parallel connected panels the output would be 8A*30V=240W.
-wrong again. Shading one third of panel reduces output by 1/3 to 8*2/3A*(30V-0.6V)=156.8W, not zero. With panels in parallel the output would be 156.8W+240W+156.8W=553.6W. The output with panels in series would be 8A*(70V-1.2V)=550.4W
...with shadows on 7 of 9 subpanels there would be 8A*20V=160W available for charging with serial panels...
-wrong again, it would be more like (20V-7*0.6V)*8A=126.4W
...due to lower 20V from two panels they will not contribute any amps...
-???????? Both panels will happily contribute 2/3 of 8A or 2*(8A*2/3)*(30-0.6)V=313.6W. The third panel will contribute full 240W with a total of 553.6W.
With panels in series ALL CURRENT flows thru the bypass diodes of subpanels that are in shade. They better be in good condition and properly tightened for good contact or else you may lose charging current completely. With parallel panels only panel in shade lose output PARTIALLY. The rest of panels are unaffected.
This applies to situation as described above on drawings.
...panel shading is not always understood on this board......
-You are the one not understanding
...the same shading scenario for parallel panels means that reduced panel voltage does not contribute ...
-wrong, it does the same as for panels in series-it produces reduced output
...at high noon if I had 7 section shaded the panel output would be 20V at 8A or 160W/14.8V=10A bulk charging...
-wrong, it would be (20V-7*0.6V)*8A=15.8V*8A=126.4W/14.8V=8.54A of bulk charging at 14.8V
...assuming 8A the output would be 8A*70V=560W for the serial panels. For parallel connected panels the output would be 8A*30V=240W.
-wrong again. Shading one third of panel reduces output by 1/3 to 8*2/3A*(30V-0.6V)=156.8W, not zero. With panels in parallel the output would be 156.8W+240W+156.8W=553.6W. The output with panels in series would be 8A*(70V-1.2V)=550.4W
...with shadows on 7 of 9 subpanels there would be 8A*20V=160W available for charging with serial panels...
-wrong again, it would be more like (20V-7*0.6V)*8A=126.4W
...due to lower 20V from two panels they will not contribute any amps...
-???????? Both panels will happily contribute 2/3 of 8A or 2*(8A*2/3)*(30-0.6)V=313.6W. The third panel will contribute full 240W with a total of 553.6W.
With panels in series ALL CURRENT flows thru the bypass diodes of subpanels that are in shade. They better be in good condition and properly tightened for good contact or else you may lose charging current completely. With parallel panels only panel in shade lose output PARTIALLY. The rest of panels are unaffected.
This applies to situation as described above on drawings.
