Solar Panels, Leafy Shadows and Bypass Diodes
3x250W panels, 3 bypass diodes each, series connected 91Vmp. A 5-10A battery draw over the panel output was maintained until 2:08. The rig is in Casa Grande, AZ about 40 miles south of Phoenix and fac...
Forum Discussion
Sal,
I believe you were looking at the red line which is voltage with the right hand side axis. The amps at noon are 15A.
But as I'm sure you know parallel would provide more amps for full panel shade. In the case above the 6 diodes in the 2 panels would add about a 3V drop.
The bypass diodes can provide more power for partial panel shading. For example the time frame from 8:18-10:18 would have no power for parallel panels since there is shade on all 3 panels. The voltage stepping from 12:58 to 1:38 also shows effect of the diodes with partial shading.
Granted this example is panel end shade and mostly causes all 6 bypass diodes to conduct until the shadows begin to exit the front panels at 12:58. Whereas side shade would allow 1/3 or 2/3 of the panel producing power for a longer period of time.
I believe you were looking at the red line which is voltage with the right hand side axis. The amps at noon are 15A.
But as I'm sure you know parallel would provide more amps for full panel shade. In the case above the 6 diodes in the 2 panels would add about a 3V drop.
The bypass diodes can provide more power for partial panel shading. For example the time frame from 8:18-10:18 would have no power for parallel panels since there is shade on all 3 panels. The voltage stepping from 12:58 to 1:38 also shows effect of the diodes with partial shading.
Granted this example is panel end shade and mostly causes all 6 bypass diodes to conduct until the shadows begin to exit the front panels at 12:58. Whereas side shade would allow 1/3 or 2/3 of the panel producing power for a longer period of time.
