Power Centers, multiple inverters [RE-wrenches]

[Doug McCorkle]

Allan - we did one huge residential installation - 6kw PV, 2 pairs of
stacked 5548s with separate AC panels for each pair, and 96 2volt industrial
cells (750AHr cells, I think).  The recurring problem was tripping the
inverters from surge loads, until the builders finally learned how to work
with the system.  I believe one side also tripped once due to unbalanced
loads, fixed by the electrician rewiring the AC panel.
Actually, another problem there was the architect - they tend to go lighting
crazy - this place had 2500 watts of CEILING lights! (it was a 100x40
two-story garage downstairs and living space upstairs).  Of course, he said,
"you don't _have_ to turn them on!"
Doug McCorkle
SunnySide Solar

-----Original Message-----
From: Allan Sindelar, Positive Energy, Inc.
[mailto:allan at positivenergy.com]
Sent: Wednesday, February 14, 2001 7:41 PM
To: New wrenches posting
Subject: Power Centers, multiple inverters [RE-wrenches]


Wrenches,
I'm in the process of designing a large grid-backup residential system, and
I don't have a Powercenter.  Is Pulse currently alive? Anybody have them do
custom work lately? Is there anybody else doing listed power centers?  I
would like something like a PC500 in 48V, but with no AC section, no charge
controller (I prefer to use multiple RVPP Solar Boost 3048s, mounted
separately), and maybe (see below) 3 DC175 breakers for 3 inverters.

Related question: Has anyone used the SW parallel stacking interface? Does
it work?  This is a BIG residential system; the G.C. (general contractor)
wants more AC capacity, but I have recommended no inverter stacking, either
series or parallel, in order to maximize simplicity and reliability. It has
been my experience that as system size exceeds proven thresholds, problems
increase disproportionately. G.C. wants to tell client that the house "can
run off the solar"; I said whoa!: no load analysis (not really possible),
too many unknown and big honkin' loads.  Rather, let's run many AC
distribution home runs, dual AC breaker panels (grid and inverter) with
gutters and close nipples between them so circuits can be switched if
needed, but let's live within the practical limits of the system, letting
grid-only handle the rest.  Advice?

Another related question: As it is, the two planned SW5548s will be
unstacked; any 240VAC loads will be run off the grid-only AC panel.  Has
anyone ever done a third inverter?  The G.C. asked about this option; I
replied I'd never been asked, but it's doable, providing that output goes to
a completely separate 120VAC load center, to run dedicated loads.  I would
imagine a [separate "DC subpanel" to inverter to AC load center] to run the
invisible luxury home needs like sump pumps, etc.  Sort of: one inverter for
motor/surge loads, one for sensitive (data/audio/video/electronic) loads,
one for lighting/appliances/house loads. Can BU grid battery charging
include the third inverter? Advice?

Thanks, Allan @Positive Energy

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For info contact list moderator by email:
 michael.welch at homepower.com

____________________________________________________________
T O P I C A  -- Learn More. Surf Less. 
Newsletters, Tips and Discussions on Topics You Choose.
http://www.topica.com/partner/tag01