Positive ground with batteries? [RE-wrenches]

Darryl Thayer daryl_solar at yahoo.com
Thu Mar 16 16:08:54 PST 2006


The chassis of the Outback MX60 is not connected to
the negative or positive.  The Chas is of the FX
series is not connected to positive or negative.  The
MX 60 can and does operate just fine with positive
ground because it is not connected.  Likewise the FX
will and does operate with either positive or negative
ground.  so go ahead and do it.  But the grounded
roofing panels can not be used on a residence. Because
the solid ground will defeat the ground fault detector
interrupter. 

As for the sunny island or Outback Island, I am
proposing a system that uses an Outback Island, and I
am beginning to feel confortable. The reason I am is
solar modules on both a barn and the house, and the
desire for no trench and emergency power.
 
Darryl

--- Geoff Greenfield <Geoff at Third-Sun.Com> wrote:

> 
> Here's a unique one:
> I am asked to design a grid tied system with battery
> back up using the new
> positive grounded Sunpower PV cells.  (not the
> Sunpower modules, but the
> cells assembled in flat roof laminates from a
> company called solar roofing
> systems).
> 
> Question # 1 - any battery based inverters allow
> positive ground?
> 
> Question #2 - Assuming NO to #1, this looks like a
> great application for AC
> bus, with an appropriate battery free box tied to a
> sub panel served by
> either a Sunny Island or Outback system.
> 
> We have not yet done an Island, it looks like they
> require an additional
> transformer to serve/tie into 120/240.  Advantage is
> modulation of SBs.
> Outback is talking about this being a viable use of
> their product as well,
> with either a 5 minute countdown based charge
> control during off grid
> operation or a Batt voltage controlled relay based
> modulation (both seem
> rough).  

Add to this the ability to use the Bergey
> Gridtek inverter and we
> are all very interested in an AC bus approach.
> 
> OK John B and Chris F (and others) lets lay out the
> pluses and minuses of
> each approach.  Efficiency during normal grid
> operation?  Scalability and
> capacity? Warranty coverage?  Field
> experience/reliability/surprises?
> 
> 
> 
> For a brighter energy future,
> 
> Geoff Greenfield
> NABCEP Certified Energy Practitioner
> 
> THIRD SUN SOLAR & WIND POWER Ltd.
> 340 West State Street
> Athens, OH 45701
> 
> www.third-sun.com
> (740) 597-3111
> 
> -
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