Larry,
It sounds like the customer can power all loads with the generator and
the non-critical load may even be the motivation for starting the
generator? How about a relay that opens the SunnyBoy output or the Sunny
Island input when the generator runs?
Kent Osterberg
Blue Mountain Solar, Inc.
www.bluemountainsolar.com
t: 541-568-4882
On 2/18/2012 6:03 AM, Larry Brown wrote:
Wrenches,
I have a client with a 4.6 kw grid tied system using a Sunny Boy 6000 inverter.
We have AC Coupled to that system with 2 Sunny Island 5048's and 8-Concorde
SunXtender 3050T 6 volt batteries in series feeding an essential load/critical
load sub panel. The wiring to the sub panel from the Sunny Islands is #6, the
max wire size that can be used in the AC 1 and AC 2, in and out, of the Sunny
Islands. The 2 pole breaker at the sub panel is 70 amps ( 56 amps feed through
current x 1.25 = 70 amps ).
This allow the 4.6 kw solar system and the Sunny Boy 6000 to act as a micro
grid and charge the batteries and support the loads in the SubPanel when the
grid is down and still be isolated from the main service panel and the grid.
We have moved several loads from the main 200 amp service panel into the
essential load/critical load panel, the well pump, the refrigerator, the
circulator/boiler controls for the propane fired radiant heating system and
some lights and communication circuits.
The main 200 amp main service panel has an integrated manual transfer switch
that has allowed them to fire up the gas powered Honda generator and run all of
the loads when the grid was down before we installed any systems to their home.
They would like to be able to continue to do this in an extended power outage.
So here is the question? In a power outage, if they fire up the generator and
move the manual transfer switch in the Main Service Panel to generator, the
Sunny Islands will see this generator power coming from the Main Service Panel
and switch from Back Up Mode to Pass Through Mode. The Sunny Boy 6000 will
send any excess power not used by the loads to the the generator (as if it was
a net metering arrangement ) believing it is the grid. This would probably
destroy the generator or some other disasterous scenario.
So how can the generator feeding the Main Service panel be isolated from the
Sunny Islands and Sunny Boy feeding the SubPanel as a micro grid in a power
outage and still provide power to the loads that are in the Main Service Panel?
Thank you for the collective wisdom and knowledge that this group has acquired
from years in the trenches making it all happen.
Larry
Larry Brown
Sun Mountain
NABCEP Certified PV Installer
_______________________________________________
List sponsored by Home Power magazine
List Address: RE-wrenches@lists.re-wrenches.org
Options & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
List rules & etiquette:
www.re-wrenches.org/etiquette.htm
Check out participant bios:
www.members.re-wrenches.org
