hi voltage array combiners [RE-wrenches]

[Larry Crutcher, Starlight Solar]

Esteemed Wrenches, 

I was looking at the SMA combiner last week and I am a little puzzled. 

They are using a Square D HU361 disconnect to build the combiner. SMA 
rates the disconnect at 40 amperes. However, Sq D has issued a data 
bulletin, Document Number 3110DB0401, that has specific UL limits when 
used for PV system disconnect.

Page 1 of the bulletin is for "General DC Systems". Page 2 has the 
specifications for PV use. At the top of page 2 is this note, "Heavy 
duty safety switches may be used on photovoltaic systems with a grounded 
feed. Refer to Figures 1B, 1D and 2." The SMA combiner is not wired 
according to any figure on this data sheet. They have landed two legs on 
the two outer poles and then combined the DC before it feeds the load.  
There is a limit of 11.5 ampere per leg (table 1 Limitations) when wired 
according to figure 1B, 1D and 2.

I asked the SMA rep and he told me it was approved by UL. So how can 
this be a UL listed 40 amp disconnect? Am I missing something?

Larry Crutcher
Starlight Solar
Yuma, AZ 



Steve Johnson wrote:
> 
> 
> Jay,
> I've been using the SMA Combi-Switch for up to 4 strings. It works fine 
> but is a little crowded.  You need a tiny screwdriver for the neutral 
> block.  I think Sq D makes em for SMA.  I'm about to try their new built 
> 
> in disconnect/combiner for the US series inverters.
> Interested in hearing what other people are using.
> Steve
> 
> 
> jay peltz wrote:
> > 
> > HI All,
> > 
> > I"m curious what folks are using/recommending for hi-voltage array  
> > combiners.
> > I"m talking about +150vdc.
> > 
> > thanks,
> > 
> > jay
> > 
> > peltz power
> > 
> > 
> 
> 
> 
> Steve Johnson
> LightWave Solar Electric
> Nashville, Tennessee


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