<html><body><span style="font-family:Verdana; color:#000000; font-size:10pt;"><div>If it were me (Depending on how big the back up loads are), I'd make the array direct grid tie, and then set up a smaller stand alone system (At the house) for critical <span>loads<span id="GD__CURSOR"> </span></span>back up.. more like a big UPS.. (no DC in)<br></div><div>db<br></div><div><br>Dan Brown<br>Foxfire Energy Corp.<br>Renewable Energy Systems<br>(802)-483-2564<br><a href="http://www.Foxfire-Energy.com">www.Foxfire-Energy.com</a><br>NABCEP #092907-44</div><div><br><br></div>
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-------- Original Message --------<br>
Subject: Re: [RE-wrenches] Invert first?<br>
From: Dan Fink <<a href="mailto:buckville@hughes.net">buckville@hughes.net</a>><br>
Date: Sun, October 02, 2011 12:50 pm<br>
To: RE-wrenches <<a href="mailto:re-wrenches@lists.re-wrenches.org">re-wrenches@lists.re-wrenches.org</a>><br>
<br>
Hi Eric;<br>
<br>
I'll be very interested to hear what others on this list who have far <br>
more experience than me in large systems have to say about this.<br>
<br>
But my first thought is, go DC. The new Xantrex XW high voltage MPPT <br>
charge controller will take up to 600 Voc from PV and put it into a <br>
standard battery bank, that roughly puts you realistically at just 30 <br>
amps in your DC lines.<br>
<br>
How were you planning to invert to AC at the PV array? Enphase etc? How <br>
do you do battery backup with an Enphase system (I have no idea, but am <br>
eager to learn from others here)? Any standard islanding grid-tie <br>
inverter will need to be right next to the battery bank.<br>
<br>
Dan Fink<br>
Executive Director;<br>
Buckville Energy Consulting<br>
Buckville Publications LLC<br>
NABCEP / IREC / ISPQ accredited Continuing Education Providers<br>
<a href="http://www.buckville.com">http://www.buckville.com</a>/<br>
<a href="mailto:info@buckville.com">info@buckville.com</a><br>
970.672.4342 (voicemail)<br>
970.373.1311 (fax)<br>
<br>
<br>
<br>
Eric Thomas wrote:<br>
> Wrenches,<br>
> <br>
> We are designing a super high end grid-tied w/ battery backup system for <br>
> a customer. Array will be ~15kW; pole or stand alone structure mounted; <br>
> 250' from home/batteries. My question is: does it make any sense to <br>
> invert the power at the array and use this ac to make the long run to <br>
> the batteries THEN connect to a typical battery charger rather than a dc <br>
> charge controller? Im mostly concerned with huge dc conductors making <br>
> this run across the property. Havent delved into the specific design <br>
> enough to size said conductors yet, or specify any equipment, but wanted <br>
> to know if im barking up the wrong tree ir not.<br>
> Thanks for the insight.<br>
> <br>
> Eric Thomas<br>
> Founder<br>
> Solar Epiphany LLC<br>
> NABCEP Certified PV Installer<br>
> WA Electrical Contractor # SOLAREL911NR<br>
> <br>
> <br>
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