Nov 2023 Performed a test with a 12 IQ8+ sub-array and grid profile "IEEE 1547 2018" late Wednesday with only 80W of solar. AC coupling started, but I noticed the often reported flicker - small variations in XW voltage - where the XW-Pro oscillates between charging and idle. There wasn't enough PV power and not enough time remaining to do any meaningful testing. Did not see any flicker when Hoymiles inverters were AC-coupled, but will perform a more structured test where production is close to load. Will be using an Ahoy DTU where inverter power can be dynamically changed. Next on my list is a test with 2 IQ8's on battery to see if the flicker can be reproduced with 600W of IQ8 constant production and variable 600W consumption. Have one regional non-AI profile I'm going to test next week. Now we have 12"+ of new snow and live PV testing needs to wait. Enphase disclosed on the support website that IQ8 inverters perform group 1 impedance testing, but that does not mean that they use identical algorithms and parameters in all available profiles and firmware versions. They have also published the UL AI testing reports - for the IQ8 models and applicable firmware at the time of testing. ------------------ Jan 2024 Finally, I got a response to an Enphase ticket after a few rounds of communications and Enphase has a new IQ8+ firmware version r06-v02.61.01 supporting AC coupling with IQ8 inverters. They upgraded 38 IQ8's last night and I tested AC coupling this morning. IQ8+ AC coupling with a single XW-Pro 6848 is working, more tests pending. 12 IQ8+ with limited solar input producing 1.6 kW max. The other panels were all snow covered so I tested only 12 IQ8's that were producing. The most challenging test I could do was PV production at max 1.6 kW with SOC max set to 97% and no load other than a 60W idle consumption by the XW-Pro plus a 5W LED light. The XW-Pro switches the IQ8's off with FW at 61 Hz, takes 1-2 sec. The XW-Pro idle consumption at 60W is too low to achieve a steady-state FW where IQ8's would produce right around 60W. There is oscillation around 60-61 Hz ramping IQ8's up for 2-3 sec and switching them off for 30-60 sec. There is no flicker on a 5W LED test light nor any significant change in AC voltage during the oscillations. Will do more testing over the next weeks as I get more PV production. If you want to try IQ8 AC coupling ask Enphase for a firmware upgrade to r06-v02.61.01. The new firmware should work with any grid profile. Source: https://diysolarforum.com/threads/how-to-ac-couple-enphase-iq8-w-battery-storage-to-schneider-xw-pro-6848-w-rack-batteries-off-grid.50433/post-974750 ------------------- Could be same or newer firmware, Enphase said anything below ...2.61 would not AC couple and changing grid profiles would not make a difference. Enphase needs to increase micro inverter sales and fend off competition by Hoymiles and AP Systems. While successful IQ8 AC coupling may cut into sales of Enphase battery backup systems, it will increase IQ8 sales into non-Enphase backup systems, like EG4 18kpv and others. ----------------- Here is the doc. A bit light on details. You can maybe tag one of the EG4 folks to try to get more info. https://eg4electronics.com/backend/wp-content/uploads/2023/04/EG4-18kPV-AC-Couple-with-Enphase-IQ8.pdf