Multi-Contact parallel connectors [RE-wrenches]

Ray Walters remotech at taosnm.com
Tue May 21 08:25:32 PDT 2002


Hi Bill;

The Bp2150 is a 24 vdc nom. module, so 2 modules in series make 48 vdcnom..
Short Circuit current for the series string is 4.75 amps. I parallel 2
strings for 9.5 amps. With the NEC 1.56 multiplier that comes to just over
15 amps, which is the series string fuse rating of the modules and the MC
connectors. The parallel harness is UL listed and came from the module
manufacturer BP. While you might be able to parallel three strings without
trouble( Asc = 14.25), I wouldn't do it and it wouldn't meet code.
Each 4 module subarray backfeeds a 15 amp QO breaker in a load center.Each
leg of the load center feeds seperate RV solarboost 3048 controllers. (I
put in a sepearate neg. "nuetral bar" since the solar boost has problems w/
combining neg. before the controllers)Max Asc to each controller is 23.75
amps which conforms to the 80% loading reccomended by Rick @ RV power and
the NEC.( I brought 2 paralleled strings 2 x 9.5 A and a 3rd single string
4.75 A in ) I'm sure somebody out there doesn't like QO breakers for this
application, but the ratings I've seen cover it and the real world testing
confirms it: I have never had a QO breaker fail, when properly designed and
installed, but I have seen multiple failures of the fused combiner boxes.
At the battery side of the controllers, I used 40 amp QOU breakers (30 amp
rated output from controller at 80% of breaker) that feed an ILSCO combiner
block that then feeds a class T fused Bolt Switch disconnect to the
batteries. Anybody see any problems with this? 

>Ray,
>
>Are you really using a harness that parallels 4 strings of modules? Could
>you explain your 4 modules in parallel/series for 48 Vdc statement. I see
>that as 16, BP2150 modules for 2400-Watt STC array. Max series fuse is 15
>amps and 4 2150's in parallel would be 19.5 amps before NEC upgrades--am I
>missing something here? I don't understand. Thanks in advance for the
>additional information.
>
>Bill.
>

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