Multifamily with multiple electrical services interconnection

[isurf]

Hey all,

Was curious if anyone had experience with buildings consisting of multiple electrical services and the PV interconnection. My question is if there are 2 services can the PV system be split into 2 and have half connected to each service or would all PV need to go back to a single point of interconnection (at 1 service only) for the entire building. Thanks for the insight!

 

[wwhitney]

Any given inverter would only connect to one service. But if the system is large enough to have multiple inverters (which it sounds like it would be, or is basically always true with microinverters), then you can split the inverters among the the multiple services.

Cheers, Wayne

 

[isurf]

Any given inverter would only connect to one service. But if the system is large enough to have multiple inverters (which it sounds like it would be, or is basically always true with microinverters), then you can split the inverters among the the multiple services.

Cheers, Wayne

Thank you Wayne! Its a pretty large system so the plan is split it on two separate inverters (one to each service) so I dont exceed 120% of the bus rating at the main gear.

 

[reethepink]

You will definitely want to look into the utility disconnect requirements too. Some utilities need a single utility disconnect.

 

[isurf]

You will definitely want to look into the utility disconnect requirements too. Some utilities need a single utility disconnect.

Yep I by default always tie all the PV back to a single fused disconnect with viewing window right at the main service. Thats what brought up the thought to begin with. Since there are two services and I have an interconnection at each service (in the same building) would it be viewed like there are two disconnects or just one (at each service).

 

[wwhitney]

You will definitely want to look into the utility disconnect requirements too. Some utilities need a single utility disconnect.

A single utility disconnect per service? Or even if a building has multiple services, a single PV disconnect for the whole building? The latter would not be too hard in the case of two services (a 4-pole or 6-pole disconnect, depending on number of phases), but obviously doesn't scale up easily.

Cheers, Wayne

 

[jaggedben]

There is no general rule about this, you will need to look at all the details for the services, how they are metered, and what the utility and interconnection rules allow. And then it may still be a design question that depends on what you're trying to accomplish.

You need to understand what a service is (one connection to the utility) and understand whether you actually have 2 services or 2 meters on one service.

If you have one service, then in California you may be able to use NEM Aggregation to have one PV system credit the usage for both meters. If this is some other state you'll have to consult the laws and regulations there.

But if there are two meters and you would like to cover both, it may also just be more practical to divide the system appropriately to cover the consumption on each meter.

 

[isurf]

There is no general rule about this, you will need to look at all the details for the services, how they are metered, and what the utility and interconnection rules allow. And then it may still be a design question that depends on what you're trying to accomplish.

You need to understand what a service is (one connection to the utility) and understand whether you actually have 2 services or 2 meters on one service.

If you have one service, then in California you may be able to use NEM Aggregation to have one PV system credit the usage for both meters. If this is some other state you'll have to consult the laws and regulations there.

But if there are two meters and you would like to cover both, it may also just be more practical to divide the system appropriately to cover the consumption on each meter.

Yep this is in SCE territory. We have (2) 4000A services supplied by separate utility transformers on opposite ends of the structure. I agree this will be more of a utility issue. If SCE only allows one VNEM PV meter per parcel or if its per service might be something Ill have to reach out to the dry utility consultant to verify.

 

[jaggedben]

Yep this is in SCE territory. We have (2) 4000A services supplied by separate utility transformers on opposite ends of the structure. I agree this will be more of a utility issue. If SCE only allows one VNEM PV meter per parcel or if its per service might be something Ill have to reach out to the dry utility consultant to verify.

At least in PG&E territory, last I knew, they would only let you do VNEM for meters on the same service. So your services on opposite ends of the structure likely each need their own system. Unfair in my opinion, and maybe it's changed, but that's how it has been around here.