pendragon
Member
- Location
- Denver, CO, USA
I run a business from home that uses a fair amount of power for scientific computing servers. We have applied to our utility (Xcel) to install a 26 KW solar PV system. We would be on net metering, and the array is sized to roughly match our current usage with an allowance for PV degradation. The solar array output would be fused at 125A just before a line-side tap at our service entrance.
The house was built in 1970 with 200A single phase service that runs underground (4x0 AL 3 wire) to the utility pole where we are on an ancient 50 KVA transformer. The utility is claiming the maximum sized PV system they will allow us to install with the current infrastructure is 3.7 KW. To get anything larger they want us replace their old transformer with a new 100 KVA and bury a new 350AL line to the pole. Our service would remain at 200A.
Our OCPDs will limit the maximum current we can draw from the utility to 200A, and the maximum current we could feed to it to 125A. I don't understand why they are making this demand, other than perhaps trying to get us to foot the bill for a worn out transformer. I've looked through NEC 2017 and the utility's electrical standards, and searched online for something similar, but I've drawn a blank. Is someone able to suggest a less nefarious explanation?
The house was built in 1970 with 200A single phase service that runs underground (4x0 AL 3 wire) to the utility pole where we are on an ancient 50 KVA transformer. The utility is claiming the maximum sized PV system they will allow us to install with the current infrastructure is 3.7 KW. To get anything larger they want us replace their old transformer with a new 100 KVA and bury a new 350AL line to the pole. Our service would remain at 200A.
Our OCPDs will limit the maximum current we can draw from the utility to 200A, and the maximum current we could feed to it to 125A. I don't understand why they are making this demand, other than perhaps trying to get us to foot the bill for a worn out transformer. I've looked through NEC 2017 and the utility's electrical standards, and searched online for something similar, but I've drawn a blank. Is someone able to suggest a less nefarious explanation?