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/
i...@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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