[RE-wrenches] fusing requirement for 4 strings run to a Inverter with 2 MPPT's

[Wesley Kennedy]

Hi Al, 

My understanding of dual mppt inverters is that they are treated nearly as two inverters on the DC side. The requirement for fusing on multi string arrays has to do with the reverse flow of current in the event of a fault on one of the strings. 2 strings are safe, 3 or more and you can damage the modules in the faulted string. The separate mppt inputs serve a similar purpose in the way they prevent current flow from the 2 strings on one mppt back thru a faulted string on the other mppt input

-Wes
303-653-3073


> On Jan 27, 2016, at 7:11 AM, Allen Frishman <amfrish at aeonsolar.com> wrote:
> 
> Wrenchers,
> What is the requirement for fusing 2 strings per MPPT?     Specifically for an inverter like the Fronius Primo that has no integrated fuses.    If you run 2 strings to each MPPT do you need to fuse each string?    In this case there is a total of 4 strings which would need to be fused if using a single mppt.     
> 
> If the home runs are run in separate conduits from the array to limit the strings in the conduit to 2 per you still have all 4 strings together in the inverter.
> 
> All thoughts and feedback are appreciated.
> Al Frishman
> AeonSolar
> 
> (917) 699-6641 - cell
> (888) 460-2867
> www.aeonsolar.com
> 
> 
> _______________________________________________
> List sponsored by Redwood Alliance
> 
> List Address: RE-wrenches at lists.re-wrenches.org
> 
> Change listserver email address & settings:
> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
> 
> List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html
> 
> List rules & etiquette:
> www.re-wrenches.org/etiquette.htm
> 
> Check out or update participant bios:
> www.members.re-wrenches.org
> 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20160127/551bb463/attachment-0002.html>