My original grid tie PV system is Enphase iQ7's. I am using a Schneider XW-Pro for my hybrid battery inverter. When the grid is down, the system works great. The iQ7's are a little finicky while running off grid on the XW-Pro output, but some of it is the old firmware in my XW-Pro, I need to get it updated, but have to shut down my system to do it. As it is, 5 of my 16 iQ7's keep going off and back on, while the other 11 kept running without a problem. Enphase thinks it could just be a very slight different in the crystal frequency that is putting it closer to the edge of what a good grid is. It is all "in spec" and has gotten me through a few power failures now. Once the XW firmware is updated, I will try an off grid test and report how that goes. The "Problem" with the Schneider XW-Pro is when the grid is up and working fine, the charging goes stupid. It literally won't start a charge cycle with only AC coupled solar while on grid. We have had to use an external controller to send it commands to make it work for "Time of Use" daily energy shifting.
That WEN generator looks very good. Sure makes my 25+ year old Coleman look like the dinosaur that it is. The XW-Pro inverter has a second input, AC2, intended for a generator. During one of my longer power outages, of course it happened after I had used up most of the power in the batteries, I connected up my old generator to try and get some charge into the system. My generator is not an inverter type, the RPM of the rotor creates the AC wave. So the frequency varies directly with engine rpm. I got the governor dialed in fairly well on a new carburetor, so it was making 62 Hz with no load, and dropped to 60 Hz at about 700 watts. It is rated to output 5,000 watts with a 10 HP engine. When I connected the generator, the XW showed it was "Qualifying AC2". After about a minute, I heard the transfer relay kick in. The inverter stopped pulling battery current and the generator took on the loads. I heard the engine grunt a little as the revs dropped and caught. The loads only needed about 500 watts, so it was no problem, but then it tried to go into charge mode. I forgot what I had the charge rate set to, but it had to be over 1,500 watts. As the XW ramped up the charge current, the generator surged as the RPM dropped too low, causing the frequency to dip too low, so the X disconnected, taking the load off the generator, so the revs shot up. IT just could not hold steady enough, and kept surging and disconnecting, every time it tried to charge. That should not be a problem with the WEN inverter generator.
My "Fix" at the time was to just pug my refrigerator into the generator, and then I also plugged a 600 watt dumb charger into the generator and had that push some power into my battery bank. So the big 5,000 watt generator was only doing about 900 watts to keep my house alive. The new carb I installed on the generator has the wrong linkage to the governor. I hope to get it working a bit better for the next time I need it. I would hate to just scrap it for a new inverter generator. I have only needed it 3 times for maybe one day each, in 20 years. Hard to justify $900 on a new generator. I would rather put that into a few more solar panels.
Evidently, the Enphase system with iQ8's and an Encharge 10 does offer a generator input now. But yeah, the Enphase battery units are stupid expensive for the capacity and power capability. But what you are paying for is the development and integration. 400bird and I have had to do our own integration to make the XW-Pro inverter play nice with our existing grid tie PV solar.