AC Couple questions, EG4 18k, with Power Pro battery, Enphase M215, M250

[Johno25]

My DIY 8.4 kw grid tied solar array with Enphase M215 and M250 micro inverters are back feeding my home via a 40 amp breaker in my garage sub panel. I have ordered the EG4 18k inverter and the EG4 Power Pro battery to use for grid down-back up. I'm wiring the system for Whole House backup. My question is what happens if I leave the breaker from the garage in my main panel alone? I understand the EG4 passes thru the AC when the grid is up but, when the grid is down, will it be able to power my home and charge the battery? I understand that the micro inverters will not shutdown since they are not wired to the GEN port. I will shutdown the solar manually if the load is satisfied during an outage. I can also load dump to our two electric vehicles. Second question, can I terminate the garage sub panel feeders to the GEN port without separating the solar AC feed from this circuit? If yes, when the inverter frequency shifts will this harm any equipment in the garage (Wifi router, LED lights, garage door openers mainly)? Thank you for any feed back. I'm new to this forum but have been watching Will's Youtube channel for years.

 

[timselectric]

EG4 18k inverter

18kpv
It's not an 18k inverter.

 

[zanydroid]

My DIY 8.4 kw grid tied solar array with Enphase M215 and M250 micro inverters are back feeding my home via a 40 amp breaker in my garage sub panel. I have ordered the EG4 18k inverter and the EG4 Power Pro battery to use for grid down-back up. I'm wiring the system for Whole House backup.

It's pretty slow to answer your questions without a wiring diagram, better text formatting would also help.

My question is what happens if I leave the breaker from the garage in my main panel alone? I understand the EG4 passes thru the AC when the grid is up but, when the grid is down, will it be able to power my home and charge the battery? I understand that the micro inverters will not shutdown since they are not wired to the GEN port. I will shutdown the solar manually if the load is satisfied during an outage. I can also load dump to our two electric vehicles. Second question, can I terminate the garage sub panel feeders to the GEN port without separating the solar AC feed from this circuit? If yes, when the inverter frequency shifts will this harm any equipment in the garage (Wifi router, LED lights, garage door openers mainly)? Thank you for any feed back. I'm new to this forum but have been watching Will's Youtube channel for years.

Do M215 and M250 actually respond to frequency shift? They are pre 1741SA by years.

The AC coupled solar is supposed to go in via the gen port. It may or may not work otherwise, I suggest tagging your question in the general support thread.

Frequency shift is pretty small, it should not harm equipment. Maybe the garage door opener would have slightly different speed. BTW the utility is allowed to deviate the frequency as much as frequency shift will, so it's not necessarily worse than being on grid.

You should be able to put the subpanel on the gen port and have things work most of the time. However if frequency shift is not enough to curtail output (which if your micros do not support frequency shift, then this is higher probability. Hopefully the frequency shift will push to a point where the micros will shut themselves off) then the 18kpv reserves the right to open the relay on gen port, which would also de-power the garage.

You can consider switching to DC system, depends on the state of your wiring from the ground mounts, how much shading you have, and compatibility with the 18kpv voltage range. If you have a separate string for each ground mount that will probably be simpler when off-grid.

View attachment 167196

 

[BentleyJ]

Do M215 and M250 actually respond to frequency shift? They are pre 1741SA by years.

The M250's do shut down at 60.5Hz. I have 11 of them and can verify this. What they don't have is the newer frequency-watt control where they will gradually reduce power at 0.1Hz intervals.

I suspect the M215's will shut down as well since the original UL1741 specification predates the SA and SB supplements by several years. Did a quick search but couldn't find what year it took effect for grid-tie in CA. Was prior to 2010 for sure.

 

[zanydroid]

The M250's do shut down at 60.5Hz. I have 11 of them and can verify this. What they don't have is the newer frequency-watt control where they will gradually reduce power at 0.1Hz intervals.

I suspect the M215's will shut down as well since the original UL1741 specification predates the SA and SB supplements by several years. Did a quick search but couldn't find what year it took effect for grid-tie in CA. Was prior to 2010 for sure.

Thanks for the clarification

I think SA was mid-2010s in California. Or do you mean UL1741?

UL1741 before 1741SA had no ride-through provisions, so I wouldn't be surprised if these old inverters shutdown on a hairtrigger deviation on frequency or voltage