[RE-wrenches] PV harvest in grid-tied systems

[toddcory at finestplanet.com]

im curious david, how you measure the output of the radian since the system is grid tie/w battery backup. the only way i have seen to do this is with a kv2c meter on each 120 volt leg. is that how you are monitoring the output of the inverter?
 
thanks,
 
todd
 
 
 
 
On Wednesday, April 18, 2012 2:01am, "David Katz" <dkatz at aeesolar.com> said:



> William
> I have a grid tie system with a Outback Radian and Xantrex 600 volt charge
> controller with 4kw of modules and it sells back flawlessly.  I have revenue-grade
> monitoring on the system and I am very happy with the output.
> David Katz
> 
> Sent from my iPhone
> 
> On Apr 16, 2012, at 6:51 AM, "William Miller" <william at millersolar.com>
> wrote:
> 
> > Friends:
> >
> > There has been recent discussion on this forum about PV production in
> > grid-tied with battery systems.  I have been faced with this same problem
> > in a 3 XW system installed in 2009.
> >
> > The customer's power bill never went down.  PV harvest was abysmal.  The
> > system would create great short circuit current but would not harvest into
> > the batteries.
> >
> > It is starting to appear the XW firmware was at fault.  The inverters would
> > charge the batteries too high so the charge controllers would back
> > off.  Upgraded firmware seems to be helping, but the data set is still
> limited.
> >
> > Remember this:  just because a PV system can produce does not mean it
> > will.  The charge controller knows only one thing:  battery voltage.  If it
> > is high, production is curtailed.
> >
> > Off-grid production will also be reduced is consumption is curtailed.
> >
> > Charge controllers that can be set for grid-tied applications help, but
> > only if the inverter(s) do not keep the battery voltage too high.
> >
> > William Miller
> >
> >
> > Miller Solar
> > Voice :805-438-5600
> > email: william at millersolar.com
> > http://millersolar.com
> > License No. C-10-773985
> >
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