Question on bypass diodes

CrotalusCrotalus Solar Expert Posts: 26
I understand how the bypass diodes work and what they are for, but there is some conflicts that I have found in different documentation.

Assume the following:
a nominal 12 volt system
2 or more panels in parallel

1. You don't need bypass diodes on a 12 volt system even with more than one panel
2. If you have more than one panel you do need bypass diodes even on a 12v system

Which is true, number one or number two and why? My thoughts are because of potential shading you would want to bypass the non producing panel, but what do I know. There are people out there that are far wiser than me.



  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Question on bypass diodes

    bypass diodes are usually built into the pvs so you won't need to add any. only possible problem may be a bit of power being backfed from one pv in full sun to one being shaded and those would need blocking diodes to prevent current from flowing in the wrong direction. 2 small 12v pvs should not be bothered by this backflow of power, but many paralleled pvs could be another matter if they would all go to dump a portion of their power into 1 shaded pv. too much power going into that 1 pv would normally not be a problem needing blocking diodes if the pvs have proper fusing on them for more than 2 paralleled pvs or strings of pvs require fusing.
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