My personal experience has been off grid with a Trace DR 1512 and quite frankly as a charger they suck. As for seemless transfer from gen.set to inverter it worked flawlessly, for a while, and then that quit. I still use the inverter part of it so it has not been a total loss.
The way my system was set up the gen.set only ran after long periods of cloudy weather or when a load was to large for the inverter. While the gen.set was running the DR1512 would automatically transfer and feed through itself to household loads while charging the battery bank. Even while browsing the internet with the computer and the gen.set ran out of gas, the DR1512 use to transfer back to inverter mode without any interuption at all.
Sounds as though you want more than this. In the event of a utility power outage you want an inverter to; take over loads instantly, start the gen.set, maintain the load until the gen.set is up and running, transfer load to the gen.set, recharge the battery bank, and then transfer the load back to itself if the gen.set runs out of fuel, seamlessly.
I have seen systems such as this at hospitals (where there is one utility entrance) but not at multiple, single family dwelling residential sites (where there is several utility entrances and one gen.set.)
Am I correct in assuming that each of the homes has its own utilities meter? How many homes? Is there only one gen.set for all the homes? Whats the load in watts for each of the homes? So many questions... I think the phrase you thinking is automatic transfer switch not a shunt.
Here are some places that may intrest you. In particular read up on; auto transfer switches, terminology, definitions, formulas, Ohm law, National Electrical Code and, features, etcetera, etcetera.
http://www.elec-toolbox.com/http://www.bowerspower.com/index.htmhttp://www.electricgeneratorstore.com/http://www.xantrex.com/index.aspAnd while your at it, check out the Xantrex SW4048 here at our hosts web site Alternative Energy store!
