208 Delta/480Y transformer install

[MLynch26]

I have a 119kW solar install and they are calling for a 208 Delta/480Y transformer. The inverters are going to a AC panel board at 480 then going to the transformer to a 208 existing service. Concern is back feeding the transformer. Any feedback would be appreciated.

 

[ggunn]

I have a 119kW solar install and they are calling for a 208 Delta/480Y transformer. The inverters are going to a AC panel board at 480 then going to the transformer to a 208 existing service. Concern is back feeding the transformer. Any feedback would be appreciated.

I have done it. What are your concerns? Talk to the transformer vendor and tell them what you want to do; they will tell you what model you need. FWIW, the company I dealt with told me that their 480Y/208D step down and their 208D/480Y step up transformers are not interchangeable.

You probably will want to consult with the inverter manufacturer's field apps guys as well. Some of them are partnering with transformer companies to provide 480/208 autotransformers for each inverter so you would combine at 208V instead of at 480V. Might be cheaper.