[RE-wrenches] XWs 3 stack (was Re: Outback BOS)

[William Miller]

Mick:

Even with the upgrade there are still not enough slots.  To do a complete 
job you need the following 2 pole breakers:

Inverter out X 3
Inverter Grid in X 3
Inverter Gen in X 3
Grid Bypass X 1
Gen Bypass X 1
System output X 1 (minimum)

The above requires 12 spaces.  The new plate will fit only 9 2 pole QOU 
breakers.

There are other considerations:

The largest QOU breaker made is 125 A.  Three XW inverters will 
through-transfer 180 amps, so a 125A breaker will create a bottle neck.

Xantrex does not  (nor does anyone else) offer any means to select from two 
AC sources for bypass.  Think about it:  if you purchase a three XW system 
because the inverters offer two AC inputs, you are screwed because there 
are no internal bypass options.  You can offer to provide bypass with the 
generator OR the grid, not both, and it requires an external transfer 
switch.  See page 2-37 in the manual.  Figure 2-30 offers a grid source 
bypass but requires the external transfer switch.  What if the grid gets 
hit by lightening and takes out your inverters?  You can start the 
generator but you can't get power to your customer's house.

Fortunately there are work-arounds.  We spent considerable time thinking 
about this and we hope to market design packages to anyone who wants a 
truly complete 3 stack XW system.  Contact me off line.

William Miller


At 07:25 AM 10/23/2009, you wrote:
>Addendum: the Xantrex XW power distribution box now ships with more 
>breaker slots on the AC rail...enough to accommodate that third inverter 
>mentioned by William.
>
>There is a field upgrade kit available from Xantrex at no charge, for 
>those who have the old style box. This is a replacement DIN rail, new dead 
>front with more slots, fasteners, and even a drill bit to drill out the 
>original rivets.
>
>I have the contact name for the kit, in case anyone wishes to contact me 
>off list...or List participant Mark Edmunds would also have that information.
>
>The upgrade process is a little sketchy, because the mounting holes on my 
>replacement DIN rain were slightly imperfect compared to the holes in the 
>box. That provides another use for the courtesy drill bit...
>
>Mick Abraham, Proprietor
><http://www.abrahamsolar.com>www.abrahamsolar.com
>
>Voice: 970-731-4675
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