[RE-wrenches] More on AC coupling - SI and SB

Wed Nov 26 07:27:36 PST 2008

Matt- 

What is your prefered/recomended way to address the 240 VAC SB series (we typically dont want to use a bunch of 700s or 1800s) and the 120 VAC SI series?  We used a pair of Outback PSX-240s but that was extra work/cost.  Other (larger) transformers? Torroid coil? Eaton? I'm surprised SMA doesnt have a nice interface worked out for the North American market... 

Also wrenches... if you go down this route, invest the time ahead of time on learning/preping for the set up etc for SI in this application.  It is not out of the box ready to go, but involves a software upgrade, laptops and the right patch cord (an issue if you are 5 hours away...). 

For a brighter energy future, 

Geoff Greenfield 
Founder and CEO 
Third Sun Solar & Wind Power Ltd. 
340 West State Street, Unit 25 
Athens, OH 45701 

740.597.3111     Fax 740.597.1548 
www.Third-Sun.com 

Clean Energy - Expertly Installed 

----- "Tump" <tump at hughes.net> wrote: 
> 
Matt, I have long been interested in installing the SMA SI & SBs but I have a VERY tough time selling $9ks worth of inverters, just to get things started. 
In the system below I would not of hesitated in installing the SMA SI & SB! I too agree that w/this type of scenario described below, I  would have given quite a bit of thought to using the SMAs. Can't beat the battery charging, no charge controllers & expandability. 
 Please if there is someone out there that has had experience w/ the SMA SI & SB let us know if it is all that it is cracked up to be! 
With passport in hand, I offer my help if someone out there  has a large system like this, that will be using the SI & SB/WB  type of set up. 
TUMP 

> -----Original Message----- 
> From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Matt Tritt 
> Sent: Tuesday, November 25, 2008 9:21 PM 
> To: RE-wrenches 
> 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: 1 st load to kick on at float voltages, 2 nd to kick on at bulk voltages and 3 rd 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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