Electrical Panel Upgrade for NEC 120% Rule

[JoeNorm]

Why not tap?

 

[brad14]

A lot of good discussion on here. Just to recap, I'm not changing my 200 amp service, that will stay the same. I know there are ways to meet the 120% rule without replacing the main panel but I've been doubling up on almost all the slots and wanted to replace it anyway. I thought an easy solution would be to get a main panel with a bus bar rated for 250 amps or more along with a 200 amp main breaker. I had a hard time finding such a thing, although I'm still waiting to hear back from Eaton. My other idea was to buy a 400 amp panel and put a 200amp main breaker in it but I'm not sure if that's something that can easily be purchased. The 400 amp panels were also pretty pricey.

I'm not sure what a panelboard is that electrofelon referenced but that sounds like something I should look into. If that lets you customize the main breaker vs the busbar, it sounds like it would work.

 

[Dennis Alwon]

You will not find a 200 amp panel with a 250 amp bus so forget that.... I imagine you can get a 400 amp main lug panel and get a 200 amp main breaker kit....

 

[electrofelon]

I'm not sure what a panelboard is that electrofelon referenced but that sounds like something I should look into. If that lets you customize the main breaker vs the busbar, it sounds like it would work.

You will not find a 200 amp panel with a 250 amp bus so forget that.... I imagine you can get a 400 amp main lug panel and get a 200 amp main breaker kit....

Absolutely you can. It will be a factory order panelboard, not a load center of course. For Siemens, it will be a P1 with a 200 A main breaker (P1's have 250 amp buss). The gear guy at you supply house can get it ordered for you.

 

[electrofelon]

If you want to browse the catalog and part number system, see pages 4 and 6 in particular:

https://www.downloads.siemens.com/download-center/Download.aspx?pos=download&fct=getasset&id1=BTLV_41311

 

[Dennis Alwon]

That is new to me however the cost will probably be much higher than the load centers.

Are the breakers standard style or bolt in? @electrofelon

 

[electrofelon]

That is new to me however the cost will probably be much higher than the load centers.

Are the breakers standard style or bolt in? @electrofelon

For Siemens, these will be bolt on only. There is another discussion going on right now about square D panelboards, and I believe those will take both plug on or bolt on.

that is the beauty of factory order panelboards you can get pretty much any thing you want: any combination of breaker spaces, main breaker size, and bus rating you can think of. Certainly it will cost more than a load center.

 

[jaggedben]

Some thoughts...

There is a Siemens 'solar ready' panel that has a 100A 'parallel energy source' auxiliary service disconnect, but it's not compliant with the 2020 code, so if that's a deal killer...

Alternatively, numerous manufacturers make a meter main with a 225A busbar and a max 200A breaker, allowing you a 70A PV breaker, which is 56A of inverter output, or 13.44kW at 240V. Is that really not sufficient for a 16 or 17kW DC solar system? That's between 1.26 and 1.19 DC to AC ratio which is totally industry standard. You may not get enough extra production with more inverter power to justify the cost of a higher rated panel.

Or is you 16-17kW PV an AC output rating?

 

[brad14]

Some thoughts...

There is a Siemens 'solar ready' panel that has a 100A 'parallel energy source' auxiliary service disconnect, but it's not compliant with the 2020 code, so if that's a deal killer...

Alternatively, numerous manufacturers make a meter main with a 225A busbar and a max 200A breaker, allowing you a 70A PV breaker, which is 56A of inverter output, or 13.44kW at 240V. Is that really not sufficient for a 16 or 17kW DC solar system? That's between 1.26 and 1.19 DC to AC ratio which is totally industry standard. You may not get enough extra production with more inverter power to justify the cost of a higher rated panel.

Or is you 16-17kW PV an AC output rating?

The 16-17 kW is an AC output so that's about 48 or so IQ7A micro inverters. With a standard 225A busbar and 200A breaker, I could get away with about 13kW. From what I understand I have to account for 125% of the possible solar load and that plus the main breaker rating must be less than 120% of the busbar rating. The panelboard seems to be the way to go I just have no idea how much extra it will cost. I'm currently trying to get that info from a local supplier.

 

[electrofelon]

The panelboard seems to be the way to go I just have no idea how much extra it will cost. I'm currently trying to get that info from a local supplier.

Based on some recent factory order panelboards I got, I would bet around $700-800 for a 250A buss with a 200 amp MB, including about 30 branch breakers. True panelbaords are super nice, but definitely cost more.

 

[Designer101]

I'm in the planning process of a solar install at my house. I'm planning on installing a PV system of about 17-18 kW. I'm trying to figure out the most economical way to satisfy the NEC 120% rule at the main panel. I was planning on replacing the main panel anyway because I've been doubling up breakers and am out of slots. My current panel has a 200 amp breaker and a 200 amp rated busbar. I thought a good solution would be to find a main breaker panel with a 200 amp main breaker and a busbar rated for over 250 amps. I tried looking for electrical panels with 250 or 300 amp busbars but haven't found any yet. It seems that most panels cap out at around 225 amps. I'm not sure if the best option is to look for a 400 amp panel and install a 200 amp breaker in it. I'm trying to get ahold of Eaton tech support but haven't heard back yet. I was wondering if someone else has run into this and has already found a solution. I briefly looked at installing 400 amp service but that was extreme overkill and quite expensive. Thanks.

You dont always have to comply with 120% rule,
there are other ways you can qualify the PV connection.
You might know code better than me though if you are EE. but 120 percent rule is the most easiest one and most used.
just find out if the ajh and utilty is very easy towards supply side connection. some POCO has Meter adapter to make this connection more easier and acceptable, here in Southern california, GMA and RMA are most used.

there is also option to do load side tap if you have sub panel somewhere.

you can relocate the all loads from main panel to sub panel and connect that sub panel to lug kit and connect the solar beaker to the main panel, there will be only one breaker in main panel if its done so. make sure your area don't follow NEC 2020 as they might not allow that connection but its fine under nec 2017.

 

[ramsy]

Had to look up Southern California Edison's "Generation Meter Adapter" (GMA), and SDGE's "Renewable Meter Adapter" (RMA).

It appears both supply-side adapters have been in use since ~2016, with designs limited to 200A max services.
Very simple meter adapters with disconnect for residential arrays. GMA handles 65A max or 15.6kw @ 240v, and 48A for RMA

Since the OP wants to connect a 75A solar array, his custom-residential system pushes meter-adapter design limits by 10 Amps

If given the oportunity to choose, would people wan't to pay $5,000 to flip the panel, for 10-more Amps beyond the meter adapter?

Rather than never knowing about meter-adapter options before signing solar-installation contracts, perhaps property owners are wiser to consult the electric utility first, for solar-array-connection options.