how do i calculate max PV amps for my panel and meter

[nanchux]

how do i calculate how many amps my PV can generate? my panel is wep4212 with 2 meters. max branch rating 225, max bus rating 400. each meter has 200amp breaker for current coming from the utility. I want to install 2 pv systems one per meter

i am confused how the 120% rule is applied. is my max pv amps 120% of 200 - breaker from utility = 240-200 =40amp or is it 120% of 225 - breaker from utility = 270-200=70amp. If I derate to 175 would max pv amps become 240-175= 65amp or 270-175=95amps

 

[wwhitney]

That WEP4212 is a dual meter main, with space for one main breaker (up to 225A) for each meter. On the grid side of the meters is a 400A bus.

The short answer should be that the 120% rule doesn't apply to that equipment. With a 200A breaker on each meter, you should be able to connect up to 160A continuous of PV inverter rating to each 200A feeder supplied by a 200A breaker.

[Note that I say should because the 120% rule may not quite be written narrowly enough to exempt that equipment, but hopefully anyone reasonable looking at the situation will agree with the above.]

What's going to matter is how the PV is connected downstream (i.e. away from the grid) from that dual meter main. If you do a load side connection in a panel that is supplied by the 200A feeder, then your limit will be the 120% rule (or other options) with respect to that panel (and any other panels between that panel and the dual meter base).

If, however, you simply splice your inverter output conductors to the 200A feeder supplied by one of the main breakers, and you comply with the feeder interconnection rules (which include that any load panel that can thereby be supplied by both PV and the grid be protected with a main breaker of no more than the feeder rating), then your only limit will again be the 160A continuous limit previously mentioned.

Cheers, Wayne

 

[nanchux]

Thanks. Where does the 160A you mentioned come from? Is there a wiring diagram that you can share?

 

[wwhitney]

Thanks. Where does the 160A you mentioned come from? Is there a wiring diagram that you can share?

160A continuous load * 125% continuous use factor = 200A ampacity / OCPD size for non-100% rated OCPD.

As to the wiring diagram, the schematic is in the upper right of the link you provided.

Cheers, Wayne

 

[CrazyRabbit]

What is the purpose of a split meter? Only reason I can imagine is the utility doesn’t have 400 amp meters!

 

[nanchux]

What is the purpose of a split meter? Only reason I can imagine is the utility doesn’t have 400 amp meters!

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