How EXACTLY does the EG4 3000 tie into the breaker panel?

[RonS]

The local permit agent thinks I need a "grid tie relay" between the EG4 all-in-one unit and the house panel which will govern particular appliances and not general appliances. He's of the mind that the unit cannot govern when the grid is used for appliances and when the solar or battery is used. I thought the EG4 3000EHV would do that, but he's not familiar with it.

I tried over 3 weeks to find an electrician that could give me the answer and none will talk to me about it—they're all busy with new construction and don't want to be bothered.

I'm attaching my electrical plan (created by me), but I realize it's fuzzy on how the EG4 will connect to the panel because I haven't been able to get an electrician to help. I was hoping the permit office could tell me, but no. I was suspicious I might need a subpanel between the EG4 and the panel, but again, no help.

Hoping someone can?

Thanks in advance.
Ron

 

[x98myers7]

a generator manual transfer switch is what you need. you feed the transfer switch generator input from the EG4 then feed the critical loads from there.

a transfer switch will allow you to change the input from generator(PV) or the grid. you need this type of interconnect to prevent any possibility of backfeeding PV power to the main panel.

https://smile.amazon.com/Reliance-Controls-Corporation-30310A-Generators/dp/B001HX7FH0

some people go with a critical loads subpanel, but IMO... this is a simpler route as it allows you to select specific circuits to put on PV or the grid as needed. some people go with automatic transfer switches. it all comes down to how much $ you want to spend.

 

[RonS]

Generac has a 16-circuit automatic transfer switch for $579 and Kohler has one for $550. The extra $200 seems worth it.

However, the EG4 3000 manual says, Overload bypass: (When enabled, the unit will transfer to line mode if overload occurs in battery mode.)

Isn't that a transfer switch of sorts?

 

[Mattb4]

Generac has a 16-circuit automatic transfer switch for $579 and Kohler has one for $550. The extra $200 seems worth it.

However, the EG4 3000 manual says, Overload bypass: (When enabled, the unit will transfer to line mode if overload occurs in battery mode.)

Isn't that a transfer switch of sorts?

Yes and no. It auto transfers between using AC to supply downstream loads and Solar/battery/inverter to supply downstream loads. It is not the same as a transfer switch that you place between your supply to Main and to an emergency power supply. Think of it like a computer UPS.

Normally you supply power to these inverters and from them you feed loads. Those loads are not in parallel with the Mains loads they do not connect to the main panel. That would require a grid tie. Using a transfer switch before the main panel would allow chosing between utilty power or your emergency power.

Mains AC=>EG4 AC in
Solar=>EG4
Inverter bypass=> Main AC out to load whether a sub panel or direct.
Solar/battery/inverter=> inverter AC out to load whether a sub panel or direct.

 

[RonS]

I have some additional information from Signature Solar:

Hello Ron,

I spoke with the tech dept about this.
They do say that you will need an ac out panel for this system.
You do not need a transfer switch for this unit.

--
Brent Gentry
Signature Solar LLC
1130 Como St South
Sulphur Springs, TX 75482
903-441-2090 Ext-133

 

[RonS]

Thanks, Matt, that's helpful!

Am I understanding correctly that I will need a subpanel going to Main AC?

 

[RonS]

.

 

[Mattb4]

Thanks, Matt, that's helpful!

Am I understanding correctly that I will need a subpanel going to Main AC?

No. The subpanel is what you connect from the inverters AC output. You need a circuit from the main panel to power the "AC In" side of the Inverter.

Some folks will use an auto or manual transfer switch before the subpanel so that either main AC (a circuit for the subpanel running to the transfer switch is added to the main panel.) or inverter AC can be selected.

Some even put that transfer switch before the main panel and than have a circuit ahead of it to supply AC to the inverter. The thing to keep in mind is you can not have the inverters output connected to any panel that the utility is also connected to. That would require running in parallel or "grid tied".

 

[RonS]

I'm an artist, not an electrician, Matt. Is this what you mean?

 

[Mattb4]

Sorry I am no artist or good at computer drawing. But your drawing will not work

 

[RonS]

Oof. Sorry, I'm really not an electrician. I guess I'm not understanding what you mean by "The subpanel is what you connect from the inverters AC output. You need a circuit from the main panel to power the "AC In" side of the Inverter."

Hmm. By Main AC do you mean what's coming in from the outside rather than the panel? I know, I can hear, "Duh!" =)

If that's the case, exactly where do I connect to the Main AC? At the main panel junction (which is what I thought) or somewhere before that?

 

[Mattb4]

Yes, anytime I used the word Main or utility AC I was referring to the power you get from your electric company.

ETA: I tried searching for a drawing on the net I could link to but all the ones I found were too simple or would not apply for this kind of setup.

 

[TomC4306]

I added a circuit breaker to my main AC panel and wired from that to the input of the inverter. From the output of the inverter to a manual transfer switch. In this manual transfer switch I had already installed it for using with a generator so had already pulled 10 circuits out of my main house panel and routed those circuits through this manual transfer switch. On the manual transfer switch are three position switches for each circuit. Grid, off, gen. Is now connected to the solar generation system

 

[TomC4306]

Blending grid, battery and solar happens in the inverters

 

[Mattb4]

deleted.

 

[RonS]

Matt,
Gee. I'm embarrassed. Embarrassed but informed. =_

Thanks for helping on football day...

So are we disconnecting the Main/utility AC from the breaker panel and sending it directly to the EG4-3000? In that case do I need a second EG4-3000 for 240V, or are we having a subpanel with only the load that I think it can handle?

Unless I buy more panels, the system is currently 8 - 255W, 37.4 VOC, 8.43A/9A ISC, 60-cell Canadian Solar panels in Series for 2040W, 299.2V, 8A. The EG4-3000 is a single phase so would need to get a second to include 240V. So, that said, I may have to consider moving some of the panel breakers to a subpanel?

--
Tom,
I'd prefer not to have to use a transfer switch, since Signature Solar says I don't need one, but at the moment I'm not sure my smaller system can handle the whole house.

 

[RonS]

Sorry guys, was watching football and didn't realize I got new stuff!

Matt, SigSolar said I should have a cutoff between the solar panels and the EG4-3000, so your drawing seems to have that. Where I'm getting a little lost is that it looks like you're suggesting I have a subpanel of "critical load" so the solar isn't carrying the whole house? That makes sense, since I probably don't have enough panels to carry the whole house.

 

[RonS]

Would that look like this? The EG4-3000 would control whether the subpanel gets utility AC or Solar or battery.

 

[Mattb4]

That drawing is getting fairly close. However at the junction to your sub-panel (labeled Breaker panel) you would need a transfer switch or breaker interlock since you show a line (junction with #5) going up presumably to another power supply. You can not parallel with the Main AC unless you have a grid tie capable inverter.

My assumptions from your drawing are:
The 100a breaker supplying "AC in" to the inverter (line 2) is from your Main AC. BTW unless I am mistaken the EG4 3000 only needs a 40a Breaker.
The battery feed from the left of the diagram is actually from PV. Likely it does not need a 100a DC breaker. (Important to not use AC rated breakers for DC circuits).
You are aware of possible NG bonds or not as the situation and code dictates.

 

[RonS]

Thanks for being so patient, Matt.

I should have labeled the Main AC—it's what #5 is attached to above the Breaker Panel. Everything else is labeled on what I've got, I just didn't want to clutter up the drawing with all the labels for you. The 100A breaker on the left is from the solar panels (I know, they look like batteries, but are panels). The ground on the solar panels is a lightning rod. Signature Solar suggested that addition as a cutoff if needed. The 100A breaker on the right is the cutoff going to the critical load panel that I expect the panels to supply. The product info says that a 40A breaker is all you need for one EG4 3000 but if you want to put more than one in series, you need a 100A breaker. I eventually want to add, so I thought I'd start with a 100A breaker. Should I not?

With the EG4-3000 Signature Solar has assured me I don't need a transfer switch. It is an all-in-one that is programmed to control the flow from the solar panels to the battery or appliances, and if the the battery gets low and there's not enough solar power to run appliances it will feed the solar power to the battery and run the appliances with the Main AC, much like an automatic transfer switch. That's why the Main AC has to run directly to the EG4 unit.

The grounds go to the subpanel and the Main AC via the EG4 3000 according to the manufacturers literature and there are places to attach the ground wire in the unit.

Does that make things more clear?