Two Pole Service Panels on 208

[jaggedben]

Yes, the part about stepping down and back up again is my issue. The part about stepping down and back up again was the reason for this original 2 questions:
...
Are 208/480 step-up transformers a new fad? For a small island, wouldn't another set of 480 3-phase feed lines be significantly cheaper and more efficient than running 208 lines large enough to handle a 175 KVA step-up transformer and the cost of the transformer?

My initial take is:
You never save money by stepping down and back up again if you have a choice about both ends. Yes, it would make more sense to send 480 and only step down where you need to.

I'm still confused about the general design.

208/480 step up transformers are a thing because they allow connecting grid tied 480V inverters to 208V utility services. (The 'primary' should be the side connected to the utility so that makes it a 'step up'.) I don't see how they are an advantage when you're not dealing with a utility and have the available option to interconnect an inverter at 480. (Who suggested it was a good idea?)

 

[jaggedben]

The inverter's output will match the generator at 480 3-phase, or 208 3- phase.

(Really? Same inverter will do both?)

 

[bellington]

(Really? Same inverter will do both?)

No, the inverter in the equipment room with the battery and generator will incorporate roof solar and output all as 480. There are two other large buildings with roof solar, but possibly no 480 equipment, so those may use 208 inverters, feeding back any excess through transformers and eventually to the battery. Or, we may provide a 480 panel for both of those building, and keep inverters synced at the 480 level.

 

[ggunn]

No, the inverter in the equipment room with the battery and generator will incorporate roof solar and output all as 480. There are two other large buildings with roof solar, but possibly no 480 equipment, so those may use 208 inverters, feeding back any excess through transformers and eventually to the battery. Or, we may provide a 480 panel for both of those building, and keep inverters synced at the 480 level.

I am having trouble following what you are saying, but I do not think there are any inverters with anywhere near a wide enough voltage window such that they can synch to either 480/277V or 208/120V. Also, the largest 208/120V inverters are a whole lot smaller than the largest 480/277V inverters.

 

[ruxton.stanislaw]

Can you please tell us the model of the inverter(s) and generator? We will see what we can come up with!