18K PV Gen Port with dedicated circuit panel and microinverter?

[Rumast21]

I've recently installed an 18k in a shed. I have some extra panels that I plan on placing on the shed roof using a microinverter into the 18K gen port because the three MPPTs are already being used. I'd like to also add a circuit panel to the shed in order to have some lighting and 120v outlets.

Is it possible to use AC coupling and connect to GEN port on the 18k into a breaker on a circuit panel and then tie in the microinverters to another breaker in the circuit panel?

I realize that the frequency shifting may cause issues with the lighting and/or devices plugged into the outlets, but they will likely not be used very often anyways.

Any help is appreciated. Thanks.

 

[Ampster]

Is it possible to use AC coupling and connect to GEN port on the 18k into a breaker on a circuit panel and then tie in the microinverters to another breaker in the circuit panel?

Yes you could tie those micros to the subpanel at the shed and feed the shed off the circuit panel. With that few micos I don't think it is important to run that through the GEN port. Those micros will just feed the loads in that shed and the other circuit panel. The only time frequency shifting is important is when the grid is down and if the 18k is anything like my SolArk, the GEN port is only used to give the inverter a quick way to shut down the micros if the loads are not sufficient and frequency shift is going to take too long. I don't know how many micros you are talking about compared to the wattage of your DC coupled solar but if the ratio is small there should not be an issue. In my case I have 8 kW of micros and only 3kW of DC coupled solar so I need to use the GEN port because my loads are sometimes only 700 Watts and the SolArk needs that option to shut down that much AC coupled solar if the grid goes down during the middle of the day.

 

[Rumast21]

Yes you could tie those micros to the subpanel at the shed and feed the shed off the circuit panel. With that few micos I don't think it is important to run that through the GEN port. Those micros will just feed the loads in that shed and the other circuit panel. The only time frequency shifting is important is when the grid is down and if the 18k is anything like my SolArk, the GEN port is only used to give the inverter a quick way to shut down the micros if the loads are not sufficient and frequency shift is going to take too long. I don't know how many micros you are talking about compared to the wattage of your DC coupled solar but if the ratio is small there should not be an issue. In my case I have 8 kW of micros and only 3kW of DC coupled solar so I need to use the GEN port because my loads are sometimes only 700 Watts and the SolArk needs that option to shut down that much AC coupled solar if the grid goes down during the middle of the day.

Great, that's what I thought! One question I have, is what do you mean by "With that few micos I don't think it is important to run that through the GEN port."? The GEN port is the only port I have left to use on my 18k with the microinverter.

My setup will likely be 4x 395w panels connected to a single Hoymiles microinverter, so roughly 1.6kw, which means at most 6.5 amps at 240v. My DC solar is roughly 12kw.

To be clear, I'm proposing to use the GEN port as a way to get the grid signal to the microinverter while also providing a way to access some of the grid/inverter power for my shed loads.

 

[Ampster]

One question I have, is what do you mean by "With that few micos I don't think it is important to run that through the GEN port."? The GEN port is the only port I have left to use on my 18k with the microinverter.

I assume the AC out port which feeds you circuit panel is bidirectional so it could handle some backfeed. Nothing wrong with using the GEN port but if it were me I would not want to tie it up for the benefit of just a few micros. I don't know what your overall system looks like and whether you might need the GEN port for something else in the future. Your plan would work fine. I was just going outside the box to speculate on options.

 

[Rumast21]

I assume the AC out port which feeds you circuit panel is bidirectional so it could handle some backfeed. Nothing wrong with using the GEN port but if it were me I would not want to tie it up for the benefit of just a few micros. I don't know what your overall system looks like and whether you might need the GEN port for something else in the future. Your plan would work fine. I was just going outside the box to speculate on options.

The AC out port that I'm intending to feed my circuit panel is the GEN port, which I think is bidirectional, as well as the microinverters when they are operating. I do not have any other use for the GEN port and my system is sufficient to run my house in off grid mode if necessary, so I just want an easy way to have my cake (microinverters) and eat it too (use loads in the shed) by attaching a circuit panel to my GEN port. My other option is to connect a new sub panel to the LOAD port but that messes around with the 4/0 cable, which is a PITA and unnecessary for such small shed loads.

 

[Ampster]

I just want an easy way to have my cake (microinverters) and eat it too (use loads in the shed) by attaching a circuit panel to my GEN port.

Sounds like a good plan. For the benefit of other readers who may have different circumstances a sub panel can be fed off of any other panel and does not have to directly connect to one of the AC out ports of the inverter.

 

[Rumast21]

Sounds like a good plan. For the benefit of other readers who may have different circumstances a sub panel can be fed off of any other panel and does not have to directly connect to one of the AC out ports of the inverter.

Thanks. With Sol-Ark, what happens if your loads exceeds the amps provided by the microinverters on the GEN port while AC coupling? Does the GEN port provide the remaining amperage?

 

[Ampster]

Thanks. With Sol-Ark, what happens if your loads exceeds the amps provided by the microinverters on the GEN port while AC coupling? Does the GEN port provide the remaining amperage?

Yes the GEN port is bidirectional so it provides the power. As I mentioned, my opinion why EG4 and SolArk used the GEN port for AC coupling is to be able to open the relay on that port in the event that power failed on a sunny day with no loads. There is some latency with AC coupling being able to shut down micros using frequency Watts algorithm so the GEN port relay is the fail safe mechanism instead of the micros causing the inverter to shut down in that scenario.

 

[Rumast21]

Yes the GEN port is bidirectional so it provides the power. As I mentioned, my opinion why EG4 and SolArk used the GEN port for AC coupling is to be able to open the relay on that port in the event that power failed on a sunny day with no loads. There is some latency with AC coupling being able to shut down micros using frequency Watts algorithm so the GEN port relay is the fail safe mechanism instead of the micros causing the inverter to shut down in that scenario.

That makes sense because they need to shed the load asap. Glad my idea seems to be viable.

If anyone else disagree, please let me know.

 

[timselectric]

It's a good plan.
I will be doing the same thing, at my shop (when I get to that point).
The only difference with mine, is that my Deye (hybrid AIO),(at the shop) will be back feeding my off grid system (at the house). So, the micro inverters will be connected to the gen port. (In case the SHTF)

 

[Rumast21]

It's a good plan.
I will be doing the same thing, at my shop (when I get to that point).
The only difference with mine, is that my Deye (hybrid AIO),(at the shop) will be back feeding my off grid system (at the house). So, the micro inverters will be connected to the gen port. (In case the SHTF)

Thanks, it really is amazing how flexible these AIO inverters are.

 

[Ampster]

That makes sense because they need to shed the load asap.

To be clear the GEN port is used because it can curtail the generation from the micros if the load is not enough to use the output of the micros. In your situation the inverter would curtail the DC solar first because it can be modulated much quicker and if that was not enough it would then curtail the micros in whatever fashion was determined by firmware. Yes your idea is very viable.