> > 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 > >
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