[RE-wrenches] fronius IG Plus practical engineering WAA???

[Bob-O Schultze]

Nick,
Fronius sells a heavy copper buss bar which will link all the six  
inputs together. They look sort of like the Outback PSPV bus bars  
except copper and MUCH heavier. If you need four or more inputs you'll  
need to get two of them. Three or less, cut one in half.  For some  
reason known only to Fronius in Austria, if Fronius US orders two of  
those buss bars in one packet, it costs more than two ordered  
separately. Drives Gord nuts, but that's the way it is. I just  
installed a 11.4Plus recently with the buss bars and it worked out  
pretty well. I never looked to see if there were individual fuses but  
it worked right out of the box, so....?
Combining on the roof with HV touchsafe fuses and holders is still the  
way to go, IMO, however if you are going to use a HU361 DC Disconnect  
at the inverter with four strings, you will likely need to run down  
two sets of home runs so as not to overload the poles which need to be  
derated from 30A by the usual 20%. Or, go to a 60A Disco which is  
probably more expensive than a second set of wires.
Hope this helps.
Bob-O
On Jun 20, 2009, at 12:23 PM, Nick Vida wrote:

hey Wrenches.

I opened my soon to be installed fronius IG Plus to see what was going  
on in there, and found myself a bit disappointed. There is a 6 string  
combiner in there which is fine, however there is no bypass for the  
fusing section and the terminals are rated at 20 amps. In a situation  
where you have 6 strings, you cannont combine on the roof and run down  
with a pair of conductors, instead you must run down with your  
strings. This means instead of running 3/4 conduit for 8awg pair and  
ground, I would have to run 1" conduit for 6 pairs of 10 awg and ground.
(thats a lot of flex for a 2x4!!)  So if I need a disconect on the  
roof, I would need 2 disconects, and correct me if im wrong-- but i  
would need 4 disconects in the future because this is a  
transformerless inverter.
I also noticed that they are still using those mediocre white plastic  
terminals for the ac connection that so many people found annoying.
And fyi, there are no fuses in the fusing section, so dont forget to  
order them.

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