Sol-ark wiring question (external transfer switch?)

animatt

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Hello i believe this is my first post here. I am going to try and keep it understandable, just not sure how to do that concisely.

I have a technical implementation question. I will explain what I want to do. I just can't seem to wrap my head around a solution.

Wanting to install solar but due to tricky shading part of system should be part enphase micro inverters. So partially ac coupled. Probably about 3-4kw

Currently have just a main panel. I will be splitting it up into a sub panel that is desired loads. Almost everything will actually go into critical loads panels. Only a few main energy hogs will stay in main.
Electric stove, resistive heat elements for heat pump backup, maybe electric dryer.


Ideally when operating in grid functioning normally the critical loads panel could over load the breakers of the solark. I am thinking i need to use external ATS(automatic transfer switch) between main panel and sub panel. In normal grid operation main panel would feed critical loads panel. And sol-ark load terminal would also terminate in critical loads.

Also ac coupled solar could terminate in there. All the extra solar power would back feed through main panel to sub panel connection.

Now when grid goes down i would need to discount main panel(automatically) from critical loads panel.

So sol-ark would pull from the batteries and DC coupled section and keep loads running on the critical panel. It would also allow the micro inverters to power the load panel. Providing decent solar exposure it would help running a bit larger loads than just the sol-ark could handle on its own. I would still have to load manage a bit, but would have almost everything backed up.

So i attached a rough partial sketch.
Not sure how to wire up something to make main panel disconnect and reconnect automatically. And not let the smoke out of anything.

Anything thoughts would be greatly appreciated.

Main goals. Power critical panel with more than sol-ark can pass through(in grid up condition).

When grid down have micro inverters feeding critical loads panel to take advantage of that energy. Micros could feed main panel during grid up. But i think easier to just land then in the critical loads panel.


Or maybe i am thinking about it all wrong and you guys have a better solution.

Thanks again for your time.
Matthew wright
 

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animatt

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After a bit more thought I drew in an ATS.Newly attached sketch. It can take main grid power and pass it to critical loads. Would ats detect grid down.? Main panel would still have power provided. coming from the sol-ark to critical loads then to main panel via ats.

Assuming it's did switch or disconnect main panel from critical panel. I would assume i may need to have main be connected to grid input on solar(represented by dotted line) . When main grid comes back online i would assume sol-ark would need to synchronize frequency. And just having the ats reconnect main to critical loads maybe harsh treatment of the sol-ark.

Thanks for your consideration.
Matthew
 

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svetz

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Welcome to the forums!

With the ATS, doesn't that preclude the sol-ark from charging the batteries via the grid?

Assuming I understand the drawing there is a danger because microinverters (or any grid-tied inverter) are not voltage sources (e.g., the grid or a battery are voltage sources as they hold voltage constant while you pull varying amounts of power) like people are used to (more about that in this thread). Instead they up the voltage to push as much current as they can, it's how they pump power uphill to the grid (because the grid acts like a vast sponge, the actual voltage increase is negligible, but when off-grid it isn't).

But, I think I've heard that the Sol-Ark 8k has a configurable connection that can have the microinverters plugged into it. Sol-Ark has great technical support, I'd suggest calling them to get a supported architecture.
 
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animatt

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Thanks for input.

I woke up this morning thinking about it and i am going to update drawing to the way i think should work.
--edit--- you are right about charging from grid with above diagram.
Below change in wiring consider should change that.
-- end edit---

Solark does have a webinar with gridtie connected in the load panel similar to what is drawn.
--EDIT--
starts at 15:34 --END EDIT--

But they may not add their output to the load panel that effectively during grid down. Maybe just useful for charging batteries.

Basically the dotted line which would be generator input to ats would run to load terminal on solarark. Not grid terminal.

So in grid down solark would be connected to critical loads panel.

Grid up the sol-ark would back feed main panel. Via solarks grid connection and during grid down inverter has the smarts to disconnect it.


My getting older brain is definitely not as sharp as it used to be.

Also this inverter will actually be a DEYE inverter install. So i do not want to bother solark staff with my question. That would be a bit abusive. But i did title thread solarks to get more eyes.

I ordered DEYE third party as they do not ship the USA. Inverter is going to be brought to Mexico for an install, but i did not want to deal with importation there. It can be a nightmare, at least in my previous experiences it has been.

Thanks again for reading all that.
Matthew wright
 
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animatt

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Updated drawing.
Dotted line from ats would be active on grid down event.
Grid from solark would shut off also on grid down.

I have not investigated GEN terminals on the inverter. I believe they add a bit programming capabilities that could help make things work as well.
 

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svetz

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Updated drawing.
Dotted line from ats would be active on grid down event.
Grid from solark would shut off also on grid down.

I have not investigated GEN terminals on the inverter. I believe they add a bit programming capabilities that could help make things work as well.
The updated drawing has the same problem as the original. A grid-tied inverter should not be hooked to a panel when the panel is fed by another inverter that has no "control" over the grid-tied inverter (it might look like it's working and there are plenty of youTubers that'll tell you it works great ... but it's not, see the discussion on voltage sources vs current sources in post #3). If the Sol-Arc can't handle it, there are a number of other AC Coupling solutions to work around the issue.

The good news is, from the YT video you linked the Sol-Ark has an AC IN/OUT which may be designed to do what you want to do. Write them, they can tell you for sure. I think you can get rid of the ATS because the 8kW rating is the inverter whereas the relay is rated for something higher (11kW?) ... again ask Sol-Ark, they have amazing support and can give you better answers than me.

Sol-Ark also has a 12kW model which would eliminate the extra ATS.
 

animatt

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The updated drawing was just to allow charging batteries from the grid.

I do understand what you are saying about feeding gridtie inverter to the sub panel. Paralleling with solark's load breaker.

Passthrough is 50amps. That is for both the 8k and 12k versions. If i read the manuals correctly.

I am not sure that would be high enough. I guess i can run install out and if I have an issue add the ATS.

I want most of the loads in the critical loads panel. That includes a 4 ton heat pump unit. Would be nice to run in off-grid if the power to run it is available.
I will have to install a soft start kit on the heat pump though.


Although heat pump maybe something i throw on the smart load breaker. That way I can prevent it from draining batteries too badly if solar input changes.


Battery will only be 280ah 48v lifepo4 pack.
 
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