Solar PV for Multi-family?

[designer82]

Does anyone install solar PV for multi-family buildings?

I can understand supplying the solar feed to the house panel but it wouldn't serve the tenants right? So maybe only if you have a very large house load?


Thanks

 

[jaggedben]

Depends on state regulation. For example California had a program called Virtual Net Metering that allowed a PV system on its own meter to provide credits to multiple tenants. But the latest version of it is poison pilled such that it isn't worth doing.

Many urban apartment buildings don't have enough roof space to provide for all the tenants, so just doing the house meter does make sense. For smaller multifamily buildings (2-3 units) it may make sense to have a separate system for each unit.

 

[designer82]

So if it was decided to add solar PV to a multi-family house panel, regarding infrasturcture.... other than installing a PV compliant net meter, it can be added even though the house panel is connected to a modular meter center?

That wouldn't matter and no special provisions would be needed right?

Just add the PV circuit load side to the house panel & the modular meter center wouldn't impede anything.

 

[jaggedben]

I think generally that would be fine. Not sure one can say definitively without seeing the equipment and knowing if the utility has any funky rules, but I've never had a problem doing it.

If there are less than 6 meters I think you typically find that each meter feeds to its own service disconnect, in which case there are no stringent rules for the conductors on the line side and thus the other meters and service entrance conductors really don't matter. So that's pretty much a slam dunk.

If you have more than 6 meters you would typically (and by code) have a main service disconnect upstream of them, and strictly speaking you have to consider the load side rules in 705.12. However since meter centers aren't panelboards, and since each meter typically has a feeder overcurrent device on its load side, you typically end up complying with 705.12(B)(1)[2020 NEC reference] without modifying anything on the line side of the house panel main breaker. There could possibly be some ticky-tack issues with a real persnickety AHJ but that hasn't happened to me (cross my fingers and knock on wood).

 

[ggunn]

It also can be an AHJ decision. Years ago I designed a PV system for the roof of a multifamily building; the municipally owned POCO requires PV meters and at the time did not allow virtual PV metering, so it was over 100 individual PV systems, all with their own PV meters and discos down in two electrical rooms. It was a real PITA to design and (especially) to install. I think that POCO now allows virtual PV metering.