[RE-wrenches] Invert first?

[Ray Walters]

I was just running some preliminary wire sizing for an array about 200 
ft away, and DC is just not the problem it used to be.
Using the Midnite Classic at higher array voltages does wonders for 
reducing wire size. I have not looked at the XW yet.
AC can't go over 240 v in this situation, so both the Classic and 
apparently the XW can do better than that. Adding losses for converting 
DC to AC to DC again, and I can't see any compelling reason to go AC at 
the array.

Ray Walters

On 10/2/2011 10:50 AM, Dan Fink wrote:
> 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
> 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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