>From an Outback application note: "Precautions Using a Generator When AC Coupling
Most residential generators, and even some commercial grade generators, are not designed to synchronize with another AC source. They may experience catastrophic failure if the other AC source is a “stiffer” source and can overpower the weaker AC coupled generator. To prevent the backfeed from the GTI into the generator, a safety relay can be utilized that disconnects the GTI inputs from the Radian AC output bus bars when the generator is started, either using the MATE3s AGS generator start function, or some other method." I'm trying to wrap my head around this concept of a stiff AC source and its implications for both the GTI and backup generator. Is it merely a matter of which source (backup genny or PV inverter) has more kw? Is there any kw ratio of one to the other where the threat of damage to one or the other source is real? And I imagine real-time loads being powered has something to do with it also. This goes back to an inquiry I posted a few days ago on remote control disconnect means of the GTI. In this case, I've got a 11kw PV inverter coupled on the AC bus with a 20kw Kohler generator and 16kw of OB Radians. The system is grid-tied. I'm beginning to wonder if a disconnect means of the GTI is actually required in all cases as Outback infers. But without solid recommendation to the contrary, I will set it up anyway. *Kirk Herander / **kirkh@vermont.solar <kirkh@vermont.solar>* *Owner|Principal, VT Solar, LLC* *Celebrating our 31st Anniversary 1991-2022!!* *www.vermont.solar* <https://nam02.safelinks.protection.outlook.com/?url=www.vermontsolarnow.com&data=02%7C01%7C%7C9f0330d75a244870112408d685311841%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636842843233477645&sdata=0NjyuKeQbEK6245SNnk8X4XnP9Q%2B%2BqtvcALkdDghvk4%3D&reserved=0> dba Vermont Solar Engineering 802.863.1202
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