[RE-wrenches] Invert first?

boB Gudgel boB at midnitesolar.com
Sun Oct 2 12:00:08 PDT 2011


On 10/2/2011 11:53 AM, dan at foxfire-energy.com wrote:
> 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 loadsback up.. more like a big 
> UPS.. (no DC in)
> db
>
> Dan Brown
> Foxfire Energy Corp.
> Renewable Energy Systems
> (802)-483-2564
> www.Foxfire-Energy.com <http://www.Foxfire-Energy.com>
> NABCEP #092907-44
>
>


You could also think about using 2 transformers, one on each end, to 
boost the AC to a few thousand volts to
cut losses.  But transformers have losses too.  Might be able to use 
some type of AC coupling as well for
the backup part ??

boB






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