480V single phase with transformers

wwstrick

Member
I have a client with a 240/480 single phase service with several transformers to step down to 120/240 at different points on the property. The property is very large and due to the distances they wanted to use the 240/480 with a transformer at each point of consumption. I will be installing solar and was thinking of just feeding his 120/240 panels with the inverter output. In some cases the energy would flow through two transformers before being consumed. Does anyone have any comments on this? What sort of losses should be anticipated at each transformer? Are there any transformer related issues that I should be careful of?
 

electrofelon

Senior Member
I have a client with a 240/480 single phase service with several transformers to step down to 120/240 at different points on the property. The property is very large and due to the distances they wanted to use the 240/480 with a transformer at each point of consumption. I will be installing solar and was thinking of just feeding his 120/240 panels with the inverter output. In some cases the energy would flow through two transformers before being consumed. Does anyone have any comments on this? What sort of losses should be anticipated at each transformer? Are there any transformer related issues that I should be careful of?
I think the primary thing (bad pun not intended) to be aware of is that you may have somewhat volotile voltage. A setup like that might already have higher than typical voltage drops with the multiple wire runs and transformers. When you add PV you could have double or more the voltage swing depending of course on the size and locations of the sources and loads. If the transformers have taps that will allow you to tweak things as necessary to keep voltage in the proper window.
 

LarryFine

Master Electrician Electric Contractor Richmond VA
I would think the general rule of higher voltage/lower current being better would apply here.
 

jaggedben

Senior Member
I gather you're having trouble finding 480V single phase inverters. :cool:

In general I think there's nothing wrong with your idea, but pay attention to what electrofelon said. Note that the only thing that really matters is the circuits between an inverter output and the service. This is where you'll see voltage drop/rise and might have voltage window issues. A transformer on another circuit that has only load is not relevant.
 

synchro

Senior Member
I gather you're having trouble finding 480V single phase inverters. :cool:

In general I think there's nothing wrong with your idea, but pay attention to what electrofelon said. Note that the only thing that really matters is the circuits between an inverter output and the service. This is where you'll see voltage drop/rise and might have voltage window issues. A transformer on another circuit that has only load is not relevant.
Which means that if you have any choice in the matter it would be best to put the solar at transformer(s) closest to the service.
 

electrofelon

Senior Member
Do any of the 240V single phase inverters support being installed in pairs L-N on a 240/480V service?

Cheers, Wayne
SMA sunny boys can be connected to "240 delta", just L1 & L2 no neutral, but not sure what it would think about one of the L's being grounded. Actually, the NEC doesn't require 240/480 to be grounded, but I am assuming it would be in practice.
 
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