Limitation to AC coupling with EG4 18K, help required...

[Ampster]

If you were to use an inverter that AC couples to the Load Output of the inverter (not the Gen input) via a breaker in the same main or subpanel.

This is the answer to the OP's question. He will get all the benefits of AC coupling when the grid is up and the generation of the AC coupled solar will pass through the EG4 and be exported after covering loads. When the grid is down he can alway disconnect the AC coupled solar if there is not enough load to absorb that generation.

 

[Ampster]

i would be shocked out of my mind if the load port is not bidirectional

I agree, and that is why the solution that @BentleyJ proposed could work when the grid is up.

 

[BKY2003]

OP, where I think the tread got off topic "AC coupling with EG4 18K" is the EG4 18Kpv is not described by EG4 for AC Coupling to the Load terminal. If that an option that you might consider I suggest looking at the SolArk. But if you wire the 18Kpv different than what EG4 presents, you are likely to get a response from SS. We did not advise against AC Coupling to the GEN PORT. Then the Warranty could be denied. They do rigorous investigation into what is going on. I know because I have experienced it. So if load side AC Coupling is what is needed, I don't think EG4 18Kpv is an option. Just wanted to clarify the difference so you could make a wise purchase.

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[ksmithaz1]

i would be shocked out of my mind if the load port is not bidirectional

I don't think the load port on the 18Kpv is 'bi-directional' in normal operation. I'm under the impression it's output only. I would think it would cause issues if you unexpectedly put power on it. Been a while since I looked at the manual, but AC coupling (microinverters) was to be done on the gen port I thought, with a soft-switch to let it blend. Load port was only for critical/all loads which allows for normal output when there is no A/C on the grid port. Please correct me if I'm wrong.

 

[millsan1]

This is the answer to the OP's question. He will get all the benefits of AC coupling when the grid is up and the generation of the AC coupled solar will pass through the EG4 and be exported after covering loads. When the grid is down he can alway disconnect the AC coupled solar if there is not enough load to absorb that generation.

There is no reason to go through these machinations.

The 18, when AC Coupled via Gen port works like this:

Grid up, gen connected to grid.

Grid down, gen connected to load.

Then, based on your config, it will run loads, feed battery, and cut off as battery gets near full (user configurable), then when battery goes down to another user set level, AC couple comes back.

In my case, I have it set to 95 as top cutoff and 90 as cut on. Again, this only comes into play when grid is down. Hen grid is up, power just flows to where it is needed.

Once configured, there is nothing the end user needs to do to make this work.

 

[Ampster]

There is no reason to go through these machinations.

One reason would be to answer the OP's question. He said he cannot AC couple his existing GT inverter and also get the benefit of the proposed DC coupled array through his proposed 12kW inverter. It would be nice to hear from @Vince Mex if what was suggested is an alternative. It is not a machination to find an optimum solution. I understand the OP has gone offline to find a solution.

 

[Quattrohead]

Surely the 18K PV and solark 15K are basically the same configuration as far as inverter and switching of ins and outs. They can do the same thing with the same settings and configuration.

 

[1201]

There is no reason to go through these machinations.

The 18, when AC Coupled via Gen port works like this:

Grid up, gen connected to grid.

Grid down, gen connected to load.

Ac couple output via gen port is not connected to loads if the grid is up?

 

[millsan1]

Ac couple output via gen port is not connected to loads if the grid is up?

Not directly. It is connected to the grid, which ultimately can/is connected to the load. I think to be accurate, one would say it can feed the load, but is not directly connected.

 

[1201]

Not directly. It is connected to the grid, which ultimately can/is connected to the load. I think to be accurate, one would say it can feed the load, but is not directly connected.

Ok so when grid is up the gen is connected to grid which is connected to load?

So all three are connected together. Otherwise it would be impossible for load to get power from ac coupled pv while on grid

 

[millsan1]

Ok so when grid is up the gen is connected to grid which is connected to load?

So all three are connected together. Otherwise it would be impossible for load to get power from ac coupled pv while on grid

Sounds about right

 

[ksmithaz1]

 

[Vince Mex]

Right after the first email exchange explaining my actual config, what i do plan to add and my goals, SS told me that AC coupling with the GEn port was the solution. They did not offer any alternatives. Now, i am waiting for the feedback of the representatives after they told me about the weird limitation of the 12 kwh of power no matter what (because as Millsan1 said, the 12 kwh limit is for the inverted power.....the AC coupled array should be able to sum to the 12 kwh....and the grid as well.....).....

 

[Ampster]

the AC coupled array should be able to sum to the 12 kwh....and the grid as well.....).....

That sounds like a good solution and consistent with what my SolArk does, subject to the limitations of total throughput determined by the breaker serving the inverter. Thanks for the update.

 

[millsan1]

Right after the first email exchange explaining my actual config, what i do plan to add and my goals, SS told me that AC coupling with the GEn port was the solution. They did not offer any alternatives. Now, i am waiting for the feedback of the representatives after they told me about the weird limitation of the 12 kwh of power no matter what (because as Millsan1 said, the 12 kwh limit is for the inverted power.....the AC coupled array should be able to sum to the 12 kwh....and the grid as well.....).....

With AC Couple, you get up to 12 PV from the 18, all of the PV from AC Coupled system and grid.

 

[ksmithaz1]

Right after the first email exchange explaining my actual config, what i do plan to add and my goals, SS told me that AC coupling with the GEn port was the solution. They did not offer any alternatives. Now, i am waiting for the feedback of the representatives after they told me about the weird limitation of the 12 kwh of power no matter what (because as Millsan1 said, the 12 kwh limit is for the inverted power.....the AC coupled array should be able to sum to the 12 kwh....and the grid as well.....).....

So as I RTFM . . . If you AC-couple you get up to 90A of cruft from the micro-inverters + another 50A from the PV. The only limitation is PV->grid which is 50A (12KW). Thus assuming you have a beast set of micro-inverters, and direct PV coming out your behind, with a single 18kpv you can push 30+KW back towards the grid lugs/panel. Assuming you've properly configured your export settings and installed the CT's properly you should be golden.

I'm not sure where the problem is, perhaps there is a mis-communication as the thread gets deep. Put the Enphase stuff on the gen lugs, turn on AC coupling. You have access to all the power, sans any direct PV over 12K, which can go to the batteries I think. Do you actually have > 12KW of direct panel output on a single unit?

At some point you have to buy more hardware and/or re-engineer, and frankly I would never run my stuff constantly at the edge of it's capability. YMMV. My 32 panel array of 4x8x455w has hit over 12, theoretically it's a little under 15, but I have it split between two. I mean if you want to mix 20 different types of solar equipment more power to you but you seemed to indicate you have ~18K of micro-inverter stuff, which should work in cahoots with the 18kpv as documented in the manual. If you are trying to get creative and use it in an undocumented manner, that is generally unwise.

From the manual:

 

[1201]

So as I RTFM . . . If you AC-couple you get up to 90A of cruft from the micro-inverters + another 50A from the PV. The only limitation is PV->grid which is 50A (12KW). Thus assuming you have a beast set of micro-inverters, and direct PV coming out your behind, with a single 18kpv you can push 30+KW back towards the grid lugs/panel. Assuming you've properly configured your export settings and installed the CT's properly you should be golden.

I'm not sure where the problem is, perhaps there is a mis-communication as the thread gets deep. Put the Enphase stuff on the gen lugs, turn on AC coupling. You have access to all the power, sans any direct PV over 12K, which can go to the batteries I think. Do you actually have > 12KW of direct panel output on a single unit?

At some point you have to buy more hardware and/or re-engineer, and frankly I would never run my stuff constantly at the edge of it's capability. YMMV. My 32 panel array of 4x8x455w has hit over 12, theoretically it's a little under 15, but I have it split between two. I mean if you want to mix 20 different types of solar equipment more power to you but you seemed to indicate you have ~18K of micro-inverter stuff, which should work in cahoots with the 18kpv as documented in the manual. If you are trying to get creative and use it in an undocumented manner, that is generally unwise.

From the manual:

View attachment 205165

I think the op thinks that if you have ac coupling on the gen port then that power is not available to the loads port.

That's wrong of course but op says that's what ss is telling them

 

[Vince Mex]

SS told me that...and i still can not figure out why because it does not make any sense...at all and would kill a lot of interest for the 18k...

I asked basic questions for my knowledge and understanding as i am buying a product to them :
- if AC coupled to 10 kwh array through the GEN port on the 18 k can i power loads greater than 12 kw ( thanks to the AC coupled power and the grid assist in case of need). Technically the total power available in that case would be 12kwh from the 18k + 10 kw from the ac coupled array + the 200 amp of grid pass through which is enormous... If grid goes down does in that case i guess total power is limited to 12 kw from the 18 k added to what the AC coupled array is able to give at that particular moment.
Limiting grid export is also important because it can not rise a certain power (10 kwh in my case) and they told me that power export can be limited.

Still waiting for their feedback......

 

[Zwy]

I think the op things that if you have ac coupling on the gen port they that power is not available to the loads port.

That's wrong of course but op says that's what ss is telling them

Not what the issue is.

Power is limited to 12Kw when AC coupled to the gen port.

The reason? A relay is present on the gen port to cut power from the AC coupled GT array as frequency shift isn't fast enough. The relay is limited to 12Kw.

That is how I see it. And Hedges explained it here.

 

[1201]

Not what the issue is.

Power is limited to 12Kw when AC coupled to the gen port.

The reason? A relay is present on the gen port to cut power from the AC coupled GT array as frequency shift isn't fast enough. The relay is limited to 12Kw.

That is how I see it. And Hedges explained it here.

Power can't be limited to 12kw if ac coupled.

If ac coupled power is passed through to the loads from the gen port then that power as available for loads in addition to the 12kw of the inverter