Advice requested for adding 4KW to existing grid-tied system

[Lat65Sol]

I purchased a home with an existing 3 KW grid-tied solar array. It has 10 x 295 watt panels with 5 x AP Systems YC500A inverters. These are wired up on a 20amp circuit connected to an AP Systems ECU-3 comms unit to monitor the output. I have full net metering so this has been a great value so far.

I want to add another 4 KW to this existing array with another 20 amp circuit. I have 10x 395w Hyundai bifacial panels and I ordered 10x IQ7A inverters. I’m not worried about directly monitoring the output of these Enphase inverters, as I can view my system’s total output via my utility smart meter.

Only after ordering this kit did I realize the Enphase requires an envoy/ communication gateway in order to active their micros (or at least this is my understanding), so I can’t just wire an Enphase string and connect it to the same service cabinet that my AP systems string is on. I’d have to wire up a separate parallel Enphase system (and pay for a $700 envoy unit), then somehow connect it to my existing solar service cabinet.

If you were in my shoes, would you:
1) Order 5x AP Systems DS-3 inverters and have both strings be AP Systems. I would the just re-sell the Enphase micros.
2) Purchase the Enphase communication system and hook up the Enphase micros so that I can view the individual output of each micro on the new string.
3) Some magical third option that allows me to utilize a string of Enphase micros via the AP systems kit.
4) Some brilliant 4th option that is eluding my tiny non-technical brain!

Thanks in advance for your help and insights. I’m happy to provide more details.

 

[chrisski]

If upgrading will get rid of a good customer friendly NEM1 agreement and land you with a POCO friendly NEM3 agreement, I’d do nothing and keep as is. Locally, adding a battery pack makes add an additional meter and would update to the current NEM agreement, so any upgrade loses money.

I would either go with option 1 which expands your current system, or option 2 that scraps the current system and goes with Enphase.

Since I don’t know either system well, I am DC coupled and What is important to me is

1) Ability to add battery capacity
2) using batteries to offset peak hours
3) in case of extended outages, the ability to charge batteries after the batteries die without AC input. (not all AC coupled systems do this.

I believe the latest enphase allows this.

I don’t like mixing equipment and getting something only you understand that takes a lot of tweaking to keep going.

 

[Lat65Sol]

Thanks for your response. Here in Alaska we don't have anything like NEM 3.0 (yet), so adding more won't change my net metering setup. This is one reason I want to install more capacity sooner rather than later.

I am planning on adding a DC -coupled system and batteries in the future, so I totally agree with your thinking there.

And I agree that its easier to have just 1 system (ie, AP Systems) rather than trying to jerry rig multiple systems. I can always use the Enphase micros for something else or resell them.

 

[MikeInKingman]

If you go Enphase, you'll want/need the Envoy for ongoing monitoring/updating and any warranty claims for the Micro Inverters, not just the commissioning of the system.
The also act as Rapid Shut Down Units, if they are required in your situation.

As far as adding more capacity, and your agreement with your Utility...You probably are obligated to inform them, if for no other reason than they can yay or nay that expansion is not going to be an issue with the capacity of the interconnect you have with them (200 or 400 amp service, or whatever it is). And most Utilities have a clause buried somewhere that if you do things tied to their grid without permission, they reserve the right to just yank your meter and tell you to go pound sand.
Stay safe, and I hope you get things worked out the way you want.

 

[Siamac]

I wanted to do the same thing. I considered enphase, but unfortunately it's not very easy at all to do that with enphase. It's cheaper and easier to do it with an all in one inverter, as long as you don't have any shade issues