I would never do AC coupled if I was adding a battery and inverter combo unless there was literally no other option. DC coupled is so much cleaner and more effective. We typically remove whatever AC inverter existed and add rapid shut down if necessary and put a Solark 15 (or AIO of choice) and battery combination of choice. Of course there is typically some added electrical work to create a back-up panel or whole Home back up. I now have a shop full of used Sma and Enphase inverters that I will need to sell. 😂 Michael D Nelson MD Electric & Solar, Inc. 707-684-0064 mobile 707-884-1862 office www.mdelectricsolar.com www.facebook.com/mdelectricandsolar On Aug 14, 2025, at 9:22 AM, William Miller via RE-wrenches <re-wrenches@lists.re-wrenches.org> wrote:
 I suppose one could add an E-gauge system with CTs in appropriate locations.
I like data. Not being able to measure AC coupled PV input is far from my ideal in my opinion, but when there is no other practical choice, I guess I would do it. In fact, I have done ita couple of times.
Jason Szumlanski Principal Solar Designer | Florida Solar Design Group
NABCEP Certified Solar Professional (PVIP)
Florida State Certified Solar Contractor CVC56956 Florida Certified Electrical Contractor EC13013208
While the AC coupled PV system can be added to the AC backed up loads panel, this defeats a lot of the functionality of a dedicated AC coupled PV array input on the AIOs and is not recommended by most of them. In theory, yes, it works on most inverters to just add it as a negative AC load -- and I've even AC coupled an old Trace SW, and it works fine on that, despite being designed and built before AC coupling was thought of.
But, if it's just on the AC loads output, the inverter does not have the ability to drop the AC PV array separately from the load if it needs to for high battery charge regulating, does not have the ability to measure the PV array input on monitoring, and may have other issues.
Zeke
> *Subject:* Re: [RE-wrenches] Adding battery to grid tie
>
> Correct me if I'm wrong: I believe AIOs can accept AC coupled power
> through the load 'output' port. That leaves the Grid and Gen inputs free
> for their roles as labelled.
>
> The AC coupled inverters connect via a breaker in the critical loads
> panel.
>
>
> William Miller
> Miller Solar.com
> 805-438-5600
> www.millersolar.com
>
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