Eric,
We have had excellent results doing these with Sunny Boys and Sunny
Islands. It is more pricey but if you have a high end customer and
want a a reliable, trouble free (?) system, we have had no wrinkles or
call backs with this approach. We have inverted at the array in the
past and sent AC to the critical loads sub panel at the house and from
there to the Sunny Islands and then either the main service panel or
done a tap between the main service panel and the utility meter. If
you do a tap then you need an AC fused disconnect before the tap. But
you could also run DC from the array to the house, if it is a new
system, and then invert to AC.
This is also a good approach if a customer wants to add battery back
up to an existing grid tie system. There is some rewiring but it is
not at the array. The output of the grid tie inverter in an AC
coupled system needs to land in the critical loads sub panel rather
than the main service panel where it probably now lands.
Magnum has a good schematic on their website showing how this is done
using a MS-PAE battery based inverter and a grid tie inverter
Larry Brown
Sun Mountain
Nabcep Certified PV Installer
On Oct 2, 2011, at 12:15 PM, 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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