[RE-wrenches] xantrex xw experiment

[Phil Undercuffler]

Nick,

The answer would be technically yes, but with limitations and I'd question
whether there would be any benefits, only downsides.

To elaborate -- yes it's possible to install two XWs on two different
batteries, using two different arrays and charging sources, but sharing the
same AC grid and backup generator (if the generator is big enough).  The key
is, they'd be totally different systems, with totally different outputs to
different protected load panels.  You might be able to stuff both systems
into one shared XW PDP, but it would require custom wiring and bypass
solutions, and any service work to one system would almost certainly mandate
shutting both systems down.  No communications or shared components between
the two systems -- so you just doubled your costs on balance of system and
metering.  No master/slave relationship would exist (each inverter is master
of its own system), so tare losses increase, and max surge capacity
decreases.  Imbalanced loads between the two systems could deplete one
battery bank and trigger a shutdown of those loads while the other bank had
reserves left to spare.

I think your client would be better off investing in a high quality battery
bank, and taking good care of it.

Phil Undercuffler
Conergy





On Tue, Mar 30, 2010 at 11:58 PM, Nick Vida <nickvida at ymail.com> wrote:

> Hi wrenches,
>
> I am looking at the xantrex XW system with 2 inverters, and I asked their
> tech support if it is possible to have 2 inverters synced to the same grid
> and backup power, but without being parraled on the battery bank. My hope
> was that the 2 inverters could switch between master and slave based on
> state of charge for 2 separate battery banks, with 2 separate charge
> controllers. The backup would be a generator, and could be 2 different
> gennies, one on each system, or perhaps one generator on a 2 inverter grid.
> I know it is a lot more inverter than what is probably needed, but i would
> really like to have 2 separate banks to avoid weaker cell issues.
> do you wrenches have any thoughts on this little dream? and no, xw cannot
> sync the frequency without being on the same battery bank with one master
> and one slave in parallel according to what I was told.
>
>
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