Registered Users Mitglied

reverse current in the array: circuit breakers take care of it?

Hello Everyone,

I'm installing a system at my house, new to solar, reading about reverse currents and noting what my module manufacturer says about this in the installation manual. QCells says I need string fuses if I have more than 2 strings in parallel. I have a Midnight Solar combiner box with their 20A breakers. Is this insufficient for preventing issues with reverse currents? My plan is 3 strings in parallel (a total of 6 strings), with 37A/120V per string.

I called QCells but haven't heard back. Here's what they say in the install manual


Any Idea , Suggestions would be appreciated,


I didn't find the right solution from the internet.


  • Registered Users Mitglied
    Employee Mitarbeiter
    maybe could have some thoughts? Or even ?
  • Registered Users Mitglied

    For me to understand the situation I have to dig into what reverse current even is in a solar array.  Essentially what happens if one solar module has a fault the other remaining modules will force their currents through the faulted string.  This can even happen if half your solar panels get covered in shade and the other half still see sun, current will increase because your shaded modules will act like a load.  The video shows this happening very well.