Yes, of course. When I have to put in a transformer to connect a 480/277V inverter to a 208/120V service, I use a delta-wye (delta to the service) and I bond N to G at the transformer.
SMA Core 1 inverters are shipped with N and G bonded with a strap that must be removed if you run a neutral conductor to the inverter.
If the X0 of the transformer _is_ bonded to the case, then what you are doing is using the EGC as the neutral, which is a separate no-no from multiple neutral bonds, and arguably worse.Because of the neutral-EGC bond at the service, if the transformer "wants" to draw any neutral current to/from X0, and X0 is bonded to the case, it will have a current path. X0 - case - EGC - neutral bond at service.
YES, but the question remains for the case of the inverter that needs a neutral connection but can use the EGC as a substitute: Why is there even an option? Why not just say "no neutral connection required" ? Saying the installer can put a jumper between N-G freaks everyone out because they don't want to "use the EGC as a neutral" so they end up running the neutral conductor. I have done dozens of megawatts of utility scale string inverter based ground mounts, and they all had a full size neutral run to the combiner panel boards and to the inverters, a complete waste, thousands and thousands of dollars. As I said, I have been out of the utility scale stuff for 4-5 years, maybe it's changing.
Because of the neutral-EGC bond at the service, if the transformer "wants" to draw any neutral current to/from X0, and X0 is bonded to the case, it will have a current path. X0 - case - EGC - neutral bond at service.
. Im all good now.
Many people have said, "why oh why did I install a wye wye.". Unless you are a POCO, then you say, "why yes, we love wye wye!"
FWIW, the SMA Core 1 inverters ship with the jumper in place; the installers have to remove it to run a neutral.
That approach makes much more sense.
Perhaps a shift in terminology would help. That is, manuals could distinguish between requiring a 'neutral conductor' to the inverter in the one case, and a 'bonding conductor to the neutral point of the system' in the other. Probably pie in the sky optimism on my part, but there you go.
Seems understandable. There is a big difference between an ungrounded source and a grounded source without a neutral (e.g. corner grounded) or with the neutral not extended.
The SMA inverter can use the EGC as a proxy for the neutral if a neutral is not run to the inverter, but a functioning neutral is still needed where the neutral is bonded to the EGC at the source of the separately derived system. So the SMA inverter needs a grounded WYE source.
I think the point is moot for large MMW utility scale inverters that still need full size neutrals. They do not have the reduced size neutral option that is needed to even consider using the EGC as a proxy. That only applies to smaller inverters that only use the neutral for voltage sensing.
Do you have an example of any utility scale inverters that are currently made today, and require full size neutrals? And is it just lack of a statement otherwise that causes them to require it, or does it actually have an operational reason for a significant amount of amps on the neutral?
I don't do utility scale, but of the commercial inverters I use, only SolarEdge does not show the neutral as optional. I do not know the reason, only that it shows a neutral connection on their data sheets and does not say that it is optional..