400a main panel needed?

[zanydroid]

My concern with the EG4 18K is that it is pretty new with complex feature set so is going to be a new adopter science fair experiment. If you are willing to contribute to the body of knowledge in the community / have the energy and wherewithal to deal with early adopter problems (up to and including some stuff beyond the basics never working; IMO stuff like SBU/SUB that’s for years been in the core feature set of this kind of minimally supported AIO/hybrid would be OK), then maybe it is an OK choice.

 

[Subestile]

My concern with the EG4 18K is that it is pretty new with complex feature set so is going to be a new adopter science fair experiment. If you are willing to contribute to the body of knowledge in the community / have the energy and wherewithal to deal with early adopter problems (up to and including some stuff beyond the basics never working; IMO stuff like SBU/SUB that’s for years been in the core feature set of this kind of minimally supported AIO/hybrid would be OK), then maybe it is an OK choice.

I agree, the solark 15k is leading for the momnet as a viable option. also available locally and I dont pay sales tax in AZ on solar equipment so that vs waiting on shipping paying out of state taxes its close enough in cost to be a wash for me. Is there a good app/website for drawing up the electrical diagrams to submit to SRP? with changing the inverter its become significantly more complex than just the additional panels/inverters into the original combiner box that it was before.

 

[zanydroid]

I agree, the solark 15k is leading for the momnet as a viable option. also available locally and I dont pay sales tax in AZ on solar equipment so that vs waiting on shipping paying out of state taxes its close enough in cost to be a wash for me. Is there a good app/website for drawing up the electrical diagrams to submit to SRP? with changing the inverter its become significantly more complex than just the additional panels/inverters into the original combiner box that it was before.

I haven’t really invested in learning the design and CAD tools. Past two projects I hired out the drawing of plans/initial design and just checked / requested changes to the calculations (breakers, wiring) and interconnection points. Those were microinverter projects but I don’t think an AIO or hybrid would be that different — the complexity of those are in understanding the config and quirks of using the different AC ports and not how to get the wires next to the box/tied into the panel.

I know some people around here have posted their Visio and Figma stencils. That’s probably efficient enough for drawing plans for yourself, vs professionals that need to draw up a lot of plans quickly enough to make money.

 

[Hedges]

I'm in the same boat.
20 years ago, a single line diagram from SMA and PowerPoint drawings were sufficient. And something sketched on plot plan.

Today, cities want .pdf with vectors not images. I've downloaded a Visio clone (from Open Office, I think) that I need to learn.
Have to show roof shape and other details.

I'd like a package with decent library of objects and snapping of walls/objects together.

I've used various real CAD at work (mostly OrCAD / Cadence), but that's all IC or PCB design. And a bit of cables.

 

[Shimmy]

I'm in the same boat.
20 years ago, a single line diagram from SMA and PowerPoint drawings were sufficient. And something sketched on plot plan.

Today, cities want .pdf with vectors not images. I've downloaded a Visio clone (from Open Office, I think) that I need to learn.
Have to show roof shape and other details.

I'd like a package with decent library of objects and snapping of walls/objects together.

I've used various real CAD at work (mostly OrCAD / Cadence), but that's all IC or PCB design. And a bit of cables.

I am buying BricsCAD; it is an AutoCAD clone-- but it is not the right software for your stated needs. It is surprising that there doesn't seem to be better software out there to address the need; I think most are relying on extensions to incumbent software options to make it an efficient process.

 

[Subestile]

I haven’t really invested in learning the design and CAD tools. Past two projects I hired out the drawing of plans/initial design and just checked / requested changes to the calculations (breakers, wiring) and interconnection points. Those were microinverter projects but I don’t think an AIO or hybrid would be that different — the complexity of those are in understanding the config and quirks of using the different AC ports and not how to get the wires next to the box/tied into the panel.

I know some people around here have posted their Visio and Figma stencils. That’s probably efficient enough for drawing plans for yourself, vs professionals that need to draw up a lot of plans quickly enough to make money.

I would be interested in a referral if the person you used is still doing diagram work.

 

[Subestile]

pretty certain that I am going to go with the solark 15k inverter and not touch the existing system other than to be able to charge the battery with the additional panels. Assuming I de-rate the main breaker to 150a would I be able to max out the solark 15k with the 19000w input (would be about 18900 actually looking at some ET 450w panel pallets currently) I know I could set the solark to just be completely offgrid but I would like to be able to sell back during the winter when I will be significantly over-producing for my needs at that point.

edit: based on the solark specs its max dc 26a per mppt and 3 mppt, assuming that I could max that out and ac coupled my existing system into the solark I would need to de-rate the main breaker to 125a allowing a max of 115a backfeed? Am I correct in this calculation?

https://www.sol-ark.com/wp-content/uploads/2022/10/15K-Specs-10-6-22.pdf

these are the panels I am looking at(450w), would be 42 panels used.

https://www.etsolar.hk/skin/tpl001/pdf/etl/166-M672BH435-455TW.pdf

 

[Shimmy]

pretty certain that I am going to go with the solark 15k inverter and not touch the existing system other than to be able to charge the battery with the additional panels. Assuming I de-rate the main breaker to 150a would I be able to max out the solark 15k with the 19000w input (would be about 18900 actually looking at some ET 450w panel pallets currently) I know I could set the solark to just be completely offgrid but I would like to be able to sell back during the winter when I will be significantly over-producing for my needs at that point.

Sorry if you said it earlier and I forgot, but where are you tying in the "load" side of the 15k? [<edit>I see you bought into the single-ended solution for the SolArk; if all your breakers are in the existing panel then that might be easiest.] If you want to minimize disruption to existing work the easiest way is to either intercept an existing sub-panel or a new critical loads panel that you cut over existing load to. All your new PV goes to the SolArk.

If you configure the SolArk for a maximum export at the point of common coupling equal to your existing PV system capacity (with external CT) then the bus can never see more than the <15kW + existing Solar. In the past inspectors were good with this.

If you want to be able to hanle an outage scenario and use all inverters and loads then it gets slightly more complicated.

 

[Subestile]

Sorry if you said it earlier and I forgot, but where are you tying in the "load" side of the 15k? [<edit>I see you bought into the single-ended solution for the SolArk; if all your breakers are in the existing panel then that might be easiest.] If you want to minimize disruption to existing work the easiest way is to either intercept an existing sub-panel or a new critical loads panel that you cut over existing load to. All your new PV goes to the SolArk.

If you configure the SolArk for a maximum export at the point of common coupling equal to your existing PV system capacity (with external CT) then the bus can never see more than the <15kW + existing Solar. In the past inspectors were good with this.

If you want to be able to hanle an outage scenario and use all inverters and loads then it gets slightly more complicated.

if your last statement means if I want to go offgrid? I think I would be ok for an outage without much issue with just the solark pv system. if it was longterm SHTF situation I would just reroute the enphase system directly through the solark so all of it could be utilized since at that point there likely would be no grid anyways.

 

[Shimmy]

if your last statement means if I want to go offgrid? I think I would be ok for an outage without much issue with just the solark pv system. if it was longterm SHTF situation I would just reroute the enphase system directly through the solark so all of it could be utilized since at that point there likely would be no grid anyways.

Just planning for prolonged outage, not SHTF. If the SolArk's PV contribution is enough to cover your minimum daily loads then you are fine.

*BUT* for a grid-down scenario (any simple outage) you need to connect something to the load side of the SolArk. The diagrams posted by @zanydroid do not have a panel on the load side; not 100% sure that is the route you are planning. Obviously, you would only be powering up equipment on that load-side panel when you have a utility outage.

 

[Subestile]

Thanks for that insight.

Just planning for prolonged outage, not SHTF. If the SolArk's PV contribution is enough to cover your minimum daily loads then you are fine.

*BUT* for a grid-down scenario (any simple outage) you need to connect something to the load side of the SolArk. The diagrams posted by @zanydroid do not have a panel on the load side; not 100% sure that is the route you are planning. Obviously, you would only be powering up equipment on that load-side panel when you have a utility outage.

is there a calculator or way to monitor total load to see if its possible to derate my main to 125a?

 

[zanydroid]

Yes, you can install an Emporia Vue to measure load.

You can also use a NEC residential load calculation spreadsheet or app.

With solar you are only allowed (as code is written) to use load calculation or energy management system to justify sizing. You cannot use measured load (however IMO this is a janky part of code so maybe you can fight it with AHJ).

With an aggressive derate on the main I wouldn’t at all be surprised if plan checker asks for the load calcs.

 

[Subestile]

Yes, you can install an Emporia Vue to measure load.

You can also use a NEC residential load calculation spreadsheet or app.

With solar you are only allowed (as code is written) to use load calculation or energy management system to justify sizing. You cannot use measured load (however IMO this is a janky part of code so maybe you can fight it with AHJ).

With an aggressive derate on the main I wouldn’t at all be surprised if plan checker asks for the load calcs.

either I'm not doing something right or its not possible to de-rate my panel at all... I guess my only option(assuming my calculation is not wrong) is to go to a 400a main panel which I am not sure is something I really want to undertake to pay for a 400a power service that I do not really need to draw from the grid

 

[zanydroid]

?? Service size and busbar rating are independent (with the exception of special case POCO rules unlikely to apply to you).

Thus you don’t have to upgrade the service.

I thought there were a lot of suggestions upthread on constructing a compliant bus from splice and tap devices in lieu of replacing MSP (which is also fine except 400A ones are pricy). I usually post those in the relevant threads here and on other solar forums I’m on. Pretty sure when I scrolled up I saw a calculation I did for you on 225A MSP if you want to do that cheaper upgrade instead (though tbh if you are going to pay someone to replace an MSP you might want to go a few steps up to simplify things, maybe).

 

[Subestile]

?? Service size and busbar rating are independent (with the exception of special case POCO rules unlikely to apply to you).

Thus you don’t have to upgrade the service.

I thought there were a lot of suggestions upthread on constructing a compliant bus from splice and tap devices in lieu of replacing MSP (which is also fine except 400A ones are pricy). I usually post those in the relevant threads here and on other solar forums I’m on. Pretty sure when I scrolled up I saw a calculation I did for you on 225A MSP if you want to do that cheaper upgrade instead (though tbh if you are going to pay someone to replace an MSP you might want to go a few steps up to simplify things, maybe).

are those subpannel setups able to be backfeed systems? ideally im going to have to go through the DER process with SRP eventually though I probably will get the system up and running offgrid first as I need/want the benefits asap to help with my summer bills

 

[zanydroid]

I am more familiar with grid tie systems, so probably. Paste the one you’re curious about, as I don’t have the capacity to organize project notes for others given I’m barely able to organize my own ongoing solar project…

Off hand what you probably want to do is empty all breakers from MSP and feed two subpanels from 125A breakers or one subpanel (with high enough ampacity busbar) from feed through lug.

 

[Subestile]

I am just using your suggestion about the previously mentioned subpanel. I don't really have any thing specific as of yet. unfortunately the brilliant installers of the original system clustered nearly everything right up against my existing main panel which will make everything much more difficult than it probably would need to be to accomplish this

 

[Subestile]

I am more familiar with grid tie systems, so probably. Paste the one you’re curious about, as I don’t have the capacity to organize project notes for others given I’m barely able to organize my own ongoing solar project…

Off hand what you probably want to do is empty all breakers from MSP and feed two subpanels from 125A breakers or one subpanel (with high enough ampacity busbar) from feed through lug.

Also I just noticed the main panel has a max 100a on the solar bus, so even if I derated to 125 this would not matter as I could not get the necessary 115a on that busbar correct? so a second panel of some sort is going to be necessary.

 

[zanydroid]

Screenshot what you are referring to/synthesize old posts into a more organized doc. I tried to help just now by going back and looking at the old posts but it’s been 4 weeks.

Solar breaker just means you have a dedicated engineered place where it is approved to take that much current. For instance on a 200A busbar with dedicated 100a solar breaker. Without the solar breaker 120% rule says you can have up to 240A of main + backfeed.

So if you derate to 125A main:
240-125=115

I believe solar breaker is equivalent to a line side tap, IE before the main breaker. Normal backfeed is after the main breaker.

 

[zanydroid]

Yes that solar breaker clearly goes into the same position as a line side tap based on the wiring diagram you shared from the panel. We went over this (I think hedges and me) back on page 2 of this thread.