AC Coupling Questions Solark and IQ8s

[jjhdtv]

Hello. Reaching out to learn more about AC coupling with my existing Solark 12k system.
I have a 10kw solar array being controlled by a Solark 12k (wish the 15k was available 3 years ago). I re-wired my home electrical to have all my 120v loads powered by the Solark 50A critical load breaker. As I'm also on natural gas (Stove, HW, central Heat), the 50A is adequate - in 3 years never tripped. Larger 240 electrical loads (pumps, AC units) rely on the grid. This was my compromise as we rarely loose power and if we do I can live without AC and a clean pool for a few days. Not so much without refrigerators, freezers, lights and electronics.

The system is also grid tied to the main panel. I still am allowed to sell power back at a 1:1 for most of the day. In addition, I have a small 10KW battery that will power my house critical loads for about 5 hours. I also switch to battery power during the expensive hours (4 to 8pm).

As I peak out power production at 8Kw, I have room for about 4Kw of AC coupling (Adding DC is not an option). My plan is to install more panels with Enphase micro-inverters (IQ8s). Most days I use 75Kwh and produce about 50Kwh. The goal is to make up the difference with AC couplling. Also, I do see electric vehicles in my future, so no fear of extra/excess power being generated.

I understand AC coupling on the Solark is done through the Gen input and switched with software. As I want to keep the option to use the generator through this breaker, I plan on using a manual A/B switch - allowing for generator or AC coupling. I realize this will require me to manually move the switch and change the software setting, but I'm ok with that.

Some questions I have: If I'm using AC coupling and the Grid goes down, is the power generated by the IQ8's still available for the Solark to manage?

What issues/problems if I connected the IQ8s generated power directly to the main panel or subpanel fed by the main panel (NOT through the Solark breaker)? Odd questions, but thats how I learn. thanks,

 

[pvgirl]

AC coupled solar connected to the gen port on the sol-ark will work off grid. AC coupled solar on the load output side of the sol-ark is not recommended. AC coupled solar on the grid side of the sol-ark will work like any other grid tied solar, it will feed loads in house or sell to grid depending on the load in the home, and won't work when the grid is out.

 

[a619]

What issues/problems if I connected the IQ8s generated power directly to the main panel or subpanel fed by the main panel (NOT through the Solark breaker)? Odd questions, but thats how I learn. thanks,

As the commenter above mentioned, there is no need to involve Sol-Ark here if you're not looking to have these panels producing power during grid down scenario. You can feed Enphase combiner output directly to your main panel and that leaves your GEN input on Sol-Ark available for generator. All you'll need is an appropriate sized breaker to backfeed power to your main panel.

Some questions I have: If I'm using AC coupling and the Grid goes down, is the power generated by the IQ8's still available for the Solark to manage?

Yes, if you go that route, Sol-Ark can use power produced by IQ8 to power your load/ charge battery. If there's excess power generated that your load + battery cannot consume, it shuts down microinverters using frequency upshifting.

 

[DIYrich]

AC couple on the gen port, and put the generator on a transfer switch on the grid input port. Setup once, and don't need to reprogram. Sol-ark can figure out whether the grid or generator is connected.

 

[DIYrich]

AC couple on the load port creates problems if the Micro inverter does not frequency disconnect. The iq8 will generate power that has nowhere to go and will fry your house. On the gen port, the sol-ark can disconnect the iq8.

 

[newbostonconst]

AC couple on the load port creates problems if the Micro inverter does not frequency disconnect. The iq8 will generate power that has nowhere to go and will fry your house. On the gen port, the sol-ark can disconnect the iq8.

Enphase micros self shutdown when voltage gets to high....not sure this is 100% correct...Micro shuts down at 264vac at the inverter....My power company supplies 255vac all day long now a days....so 127 on one side. 132 isn't that far off.

 

[Quattrohead]

I have seen reports of the iq8 being finicky so you might be better better off sticking with the previous iq7 generation that is better known.

 

[12kw_2021]

I have a 12KW PV (Iq7a inverters on each panel) system up and running ac coupled to a Sol-ark 15k on the gen port.

If/when the grid goes down the system allows the PV to continue to operate, but it is very "flaky" and will turn itself off/on during the day with full sunshine and non full batteries.

If/when your home load goes down to some low value (say 1kw or 2Kw , and the PV system is at full power sending 10Kw to the home/Sol-ark the Sol-ark will completely shut down the inverters, vs gracefully reducing and controlling the PV output to instantly match the home load.

So you end up wasting a lot of available PV, and the Sol-ark is not at all "graceful" when turning down the output of the micro-inverters to just support the home load and whatever battery charge load you have set up.

If others here have better/improved solutions.. I would love to hear them..but this is where I stopped investigating/experimenting, and concluded that only the Enphase grid profiles had the elegant control of the PV output needed to run off grid, the Sol-ark alone does not.

Note: this is for the AC coupled operation of the Sol-ark.. I don't think it is a problem if you have only DC connected PV to the Sol-ark, and as of now I don't have any DC connected PV on my setup.

The Sol-ark constantly disconnects, and reconnects the PV... and cannot "control" the Enphase PV output to match the home loads as they change during the day.

I did experiments, and found that only by changing the Enphase grid profile to a zero-export grid profile resulted in a reasonable operation of the gen connected array. I operated my system in Jan/Feb/March this year (before I was approved by my local electric company) and you can see the result in the attached image.. the home loads/battery charge/discharge was fully supported and the Enphase micro inverters power generation was perfectly controlled and zero power was exported.

Conclusion: If you want elegant control of enphase micro-inverters in an off grid situation you MUST change the Enphase grid profile to a zero export grid profile and the enphase gen connected to the Sol-ark will act as "master" and the loads supported by your Sol-ark will be supported via the gen pin connection.. it works.

If you want to rely on the Sol-ark only to control the AC coupled gen connected inverters with a default Enphase grid profile that allows export, it will "sort of" work, but will constantly fully disable, then enable the AC coupled PV and waste a lot of available PV during the day, forcing you to run down your not fully charged battery.

With help of folks here I have also confirmed that the "zero export" grid profile is resident in the memory of the Enphase combiner box mounted near the array, and I can connect to that combiner box and install the zero export grid profile if/when needed.

Hope this helps see image attached, J,F,March Enphase zero export grid profile, then mid April switched grid profile to default export any excess once home loads/battery charge complete..

 

[FlagPole]

Thanks - This is a great thread and exactly what I was looking for in planning a system. I have a 9KW inverter generator with an interlock to my mains panel and was thinking about a small rack of EG4 batteries with the 18KPV to automatically switch to batteries when the utility power goes off, and have my generator charge the batteries when low and add some Enphase solar later. Can the 18KPV automatically start my generator when the batteries get low? My generator does have a connection for automatically starting? I may reconsider the Enphase solar and go with DC solar panels or it seems like a total Enphase setup for more $$.

 

[pvgirl]

Thanks - This is a great thread and exactly what I was looking for in planning a system. I have a 9KW inverter generator with an interlock to my mains panel and was thinking about a small rack of EG4 batteries with the 18KPV to automatically switch to batteries when the utility power goes off, and have my generator charge the batteries when low and add some Enphase solar later. Can the 18KPV automatically start my generator when the batteries get low? My generator does have a connection for automatically starting? I may reconsider the Enphase solar and go with DC solar panels or it seems like a total Enphase setup for more $$.

If your generator has a 2 wire connection for remote start the 18kpv can auto start and stop it, some generators require additional parts for this interface either from the manufacture or from a third party for this interface.

If you are doing a new solar install using the DC solar inputs on the 18kpv is going to be the cheapest and easiest option in most cases.

 

[12kw_2021]

If your generator has a 2 wire connection for remote start the 18kpv can auto start and stop it, some generators require additional parts for this interface either from the manufacture or from a third party for this interface.

If you are doing a new solar install using the DC solar inputs on the 18kpv is going to be the cheapest and easiest option in most cases.

This is exactly correct, I designed my system and ordered my panels and the Enphase inverters BEFORE I decided that I didn't want a huge shiny solar array in my backyard that was useless whenever the grid went down, so I expanded my system plan to include the Sol-ark and 32 EVE 280Ah cells for ~30kWh of storage.

Initial plan was to let the Sol-ark control the PV array AC coupled on the Gen pins. I discovered that this did not work well, and it was impossible to prevent PV power export or keep the PV fully up and operating with just the limited AC coupled array control the Sol-ark has.

So I punted and investigated using zero export grid profiles installed on each Enphase micro inverter. As shared above that works perfectly for a zero export, grid connected situation.

It also works "pretty well" I would say at 80% usable if/when the grid is disconnected, and the enphase zero grid profile allows me to operate my array, supply my house, and charge my batteries when I manually disconnect the grid.

If I had it to do over, I would just connect the PV using DC direct to the Sol-ark, and I considered re-wiring and selling my Enphase inverters to save some money, but in the end decided to just stay with my initial setup, and any/all expansion will be DC PV direct connected to the Sol-ark

Only reason for doing Ac coupled PV to Sol-ark is if/when you have a panel shading issue, and need/want to get as much PV as possible with each panel operating independently.

In my case the PV array is in my backyard with zero shading concerns so I have an "overdesigned" system.

Hope this helps folks.

 

[12kw_2021]

AC coupled solar connected to the gen port on the sol-ark will work off grid. AC coupled solar on the load output side of the sol-ark is not recommended. AC coupled solar on the grid side of the sol-ark will work like any other grid tied solar, it will feed loads in house or sell to grid depending on the load in the home, and won't work when the grid is out.

Just curious what kind of results you achieved with AC coupled solar on the Gen port when off grid.

What grid profile did you use, and what Enphase inverter model?

With my 12kw array and Iq7a micro inverters gen connected, I was unable to get the Sol-ark to not export power , and if/when I did a grid disconnect the system would work, but when it got sunny and the PV power was >>> then the home loads, it would just completely shutdown the array, even if battery was at 30%.

I worked for weeks with Sol-ark tech support trying different Sol-ark settings, and nothing allowed "elegant" control of the micro inverters, and i continued to export power which (at the time) I was not supposed to be doing.

As soon as I switched to the zero export grid profile the enphase system worked perfectly for months, fully charged batteries , supported 100% of the home loads, and exported zero power, all while connnected on the gen port. (While grid connected of course)

 

[Quattrohead]

Great information, thanks to all.
I keep seeing quite a few enphase systems being removed off homes here in Florida when the roofs are replaced and people are not putting them back on, so this could be quite a nice line of equipment for future DIY use with these instructions.

 

[zephyranthes]

This is good news to hear about AC coupled solar. In my plan, I could run this way until I get around to adding some DC coupled solar to add to the reliability. Great posts here.