[RE-wrenches] More on AC coupling

[Mark Dickson]

Our customers already had the Outback gen-verter system in place from few years ago--we could not justify replacing them.  i have looked into the Sunny Islands though, and they seem like a good way to go in the future.

As an aside, I had originally planned on a Sunnyboy grid tie inverter instead of the Fronius, but it did not configure well with the new low-voltage Evergreen ESA's.  
  
Mark Dickson 
Oasis Montana Inc. 
877-627-4768 toll-free 
406-777-4309 (0830 fax) 
www.oasismontana.com 
  
www.grid-tie.com 
  
www.PVsolarpumps.com  

----------------------------------------
From: Matt Tritt <solarone at charter.net>
Sent: Tuesday, November 25, 2008 7:22 PM
To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
Subject: Re: [RE-wrenches] More on AC coupling 

I am curious as to why OutBacks were used for this system instead of
using SunnyIslands and SunnyBoys? From what I can tell about the SI
system, virtually no aspect of battery charging, auto gen-start/stop,
and interactive inverter control has been overlooked - or remains to be
engineered in the field by the installer. Because SunnyIslands have the
ability to "talk" to Sunny (or Windy)Boys, excess energy is taken care
of by "integrated load shedding" - no need for multiple relays,
dumpoads and voltage sensors. :-) The only limitation to these systems
(and only in 60 Hz land) is a maximum of 20 kW single, and 15 kW three
phase per autonomous load. I really like the flexibility of being able
to connect all AC inputs on the same line, as well as having the option
to do direct battery charging from a DC source (as long as you use a
shunt to measure current).

I know this doesn't answer your questions, but for similar applications
in the future it would be good to take a close look at the SunnyIsland
system. They're cool.

Matt T

Mark Dickson wrote:

  Hello
Wrenches, 
  On the heels
of the previous thread: 
  We just got
finished installing a system
that utilizes an Outback Quad stack and a 5.2kW array coupled to the AC
panel
via a Fronius IG5100--due to a long home-run.  The VFX's are wired
into the home in their traditional manner, providing the "grid" for
the Fronius.  As the solar comes in, excess power not used in the home
back feeds the batteries through the VFX's.  I have a series of
relays operating dump loads and finally a power cut-off for when the
batteries
reach critical level.  We installed the system yesterday and turned it
on
for a test run (then back off to power it up in 2009 for the
ITC's)-it worked great! 
    
  I have a
couple questions for you all: 

    Seems how we are back
feeding the inverters and forfeiting their charge control, where would
you set the dump loads to kick on?   

      For now I have them set
at: 1st load to kick on at float voltages, 2nd to
kick on at bulk voltages and 3rd to kick the solar power off
at the EQ voltages.  Does this make sense?  The bank is made up of
Rolls 4ks-25ps batteries.   

    Following a recent
discussion on the Wrenches list with a similar system:  Do I need to
worry about back feeding the generator if it is runnin in the morning
when the sun comes up?  Do I need a relay that will shut it down when
solar comes on line?   
    I plan on setting the
Absorb and Float set times to a miimum.  Would you recommend this? 

    
  Thanks for
your input! 

    
  Mark
Dickson  
  Oasis
Montana
Inc.  

    

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