[RE-wrenches] Utility Dis-connect for AC coupled Systems

Darryl Thayer daryl_solar at yahoo.com
Sat Apr 17 07:12:33 PDT 2010


Hi Jeff
I have used Outback inverters and not had a problem,   I use both SB and PVP for the AC side and a varity of connections on the DC side of the Outback.  
 
Frankly I have had very good success, I hope it continues.  I can not figgure out why your system would act this way.  
Darryl

--- On Sat, 4/17/10, Drake Chamberlin <drake.chamberlin at redwoodalliance.org> wrote:


From: Drake Chamberlin <drake.chamberlin at redwoodalliance.org>
Subject: Re: [RE-wrenches] Utility Dis-connect for AC coupled Systems
To: jryago at netscape.com, "RE-wrenches" <re-wrenches at lists.re-wrenches.org>
Date: Saturday, April 17, 2010, 8:59 AM


Hi Jeff, 

Use Outback off grid inverters for the backup, and break the AC from the grid tie inverters.  An advantage of this is that you can use a standard generator and transfer switch to charge batteries through the off grid inverters.  The grid tie inverters take care of the anti islanding, etc. 

Drake 


At 10:11 AM 4/16/2010, you wrote:

Hope I have not posted this before, but it keeps coming up.   We do many systems that include a battery connected inverter and generator to provide backup power for upscale homes.  Although we have no problem with roof mounted arrays, many of these homes may be large, but usually are either shaded or their roofs are broken up with all kinds of dormers and chimneys, with no large areas facing south.  

In addition, many of these homes have large landscaped yards and gardens up against the home, so we end up having to install a ground-mounted solar array as much as 200 or more feet away.  Since we want to charge the battery from the solar array during an outage, but do not want to run huge cable sizes due to the long wire runs typical for low voltage DC arrays, we mount a SunnyBoy on the back of the array, then run 240 VAC back to the battery/inverter/generator system in the basement or garage using an AC coupled design with relay cut-out to dis-connect on high battery voltage during off-grid operation.  (still not sure why inverter manufacturers can't control over-charging from back-feed AC when not grid connected).

Anyway, where to wire in the utility dis-connect that needs to be near the meter base.  The most logical is in the 240 AC output from the solar array inverter before it enters the emergency loads panel.  However, there is still the matter of the battery inverter which could easily backfeed the grid if programming is changed by others.  This would then require the dis-connect between the AC output of the battery inverter and the house panel, but this would kill the emergency loads panel if the utility actually decided to lock out.  Not likely, but still possible.  Just concerned that code officials will see the inverter in the house, a solar array in the yard, and want a dis-connect that kills everything to grid.

Have any other states already addressed this issue?

Jeff Yago


 


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Drake Chamberlin
Athens Electric
OH License 44810
CO License 3773
NABCEP TM  Certified PV Installer 
Office - 740-448-7328
Mobile - 740-856-9648 
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