I'm using the split phase option with 2 of these. They were hard to install as the internal cable connections are very cramped and not aligned with the holes on the bottom in a baffling design flaw. The programming of the options are not clear and not sure how they interact as they change with battery type and god knows what other criteria.The devices can't work without batteries and if like me, one of your batteries dies (internally short circuits to -30v) you are screwed. It would be great to be able to switch to utility/grid even if the batteries are not present.The devices use 50W of power at all times, so when for some reason, they did not switch to grid, they depleted the batteries and ended up with non functioning devices you can't restart to charge your battery with the utility power. This should be the simplest feature to add. Or add an automatic recharge if battery goes to low cutoff.The redeeming quality is that they offer split phase that most other off-grid devices do not.It was SOOOO hard to install and wire that I can't fathom returning them for another brand :-DI'll start by saying this inverter actually does work as advertised. I was able to run an air compressor and other high usage appliances without issue.Now, for why I am strongly advising NOT to buy this (unless you want a full weekend project which I outline at bottom or you do not care about monitoring your power consumption)1. The wifi monitoring DOES NOT work. Being in IT for 15 years, I assumed this was user error from all the customer reviews. I was terribly mistaken. Another reviewer here was spot on with changing server domain to server-us.growatt.com. However, that still did not resolve the issue. You will get the infamous green blinking light meaning connected to internet but can't reach Growatt server. Guess what did fix it? Finding the firmware update from watts247 for this model, connecting my laptop via USB Type B and flashing with new firmware. You would think growatt would have the firmware download, but no, see point 2 below. In summary, they shipped an inverter and wifi dongle in the same box with an incompatible firmware version which required downloading from a 3rd party site and then blamed my network (claiming port was blocked despite me proving I could telnet port 5279 from network to growatt web server). Even though I got the dongle working, I am likely going to try and get the price knocked off and return it because I built my own solution by the time I finally got it work.2. Tech support is horrific. There is no centralization and contacting anyone to get documentation on this product is impossible. From what I've gathered, they want you to go through resellers who all have their own sites and documentation, all of which are in various version states.3. I spent longer researching, learning about, then coding a monitoring solution for this inverter than I did to frame, sheath and rough-in electrical/plumbing at the tiny house this inverter is meant to power.Info below is if you are ambitious, still want the inverter, and think writing your own monitoring solution would be fun. Skip if you've read enough or aren't interested in the tech details. Hopefully, this will save someone a lot of time in the future.-Solution uses Raspberry Pi 3, influxdb, Grafana-look for solarmon on Git to see base python scripts you can use to read inverter modbus. Good luck finding the modbus RTU protocol documentation for the SPF3k. I had to use 5K which wasnt exactly right-Stream inverter data to influxdb, then visualize with grafanaWhy do all this? -you own the data and control where it goes -you control refresh rate (not the 5 minutes the growatt dongle sends) -total customization of dashboard (see image attached) -fun project if you like this type of stuff.So far working good... kinda impressed with this all in one solution, just wish i had the batteries for the 48v version.For the inverter 5 stars works really good right out of the box so far. Been testing it out and running it hard to make sure its going to work right before i give it a perment home and to my surprize its holding upNow the wifi that has to be 2 stars and my biggest complaint. The wifi dongle is a beast to setup! It was kinda the reason i got this inverter to start with because you dont have to stand over it to keep an eye on it... but at last the instructions are kinda vage at best. But i finally got it to connect and its working great! What you need to do is1) press the key button to make the dongle into a hot spot and connect to the dongle itself "192.168.10.100"2) configure the dongle to connect to your wifi (still easy peasy stuff)3) the part thats not in the manuel and the whole secret sauce go back to the dongle and you have to tell it to connect to a different server i think default is server.growatt.com or something like that you need to change it to server-us.growatt.com and magicly it will start working hopefully this helps somebody and keeps them from wasteing a day trying to figure out where you messed up.I installed this unit for an off grid expedition vehicle. Very high end system with newer 6 new solar panel array and 6 lifepo battery bank. The inverter just completely stopped working and when I contacted Spring Mirror, they put me through a battery of tests to ensure there was nothing wrong with my solar system. I complied with every step, documented as requested. After the final test, Spring Mirror asked me to repeat all of the steps AGAIN and video tape the entire process, including irrelevant things like time of day and condition of the sun, both irrelevant when I have already measure the VOC and ISC, both of which were perfectly fine. I then realized this seller and manufacturer does this to wear down the customer so they give up. BTW each test they asked me to conduct was spaced out one or two days at a time so I had to reinstall the unit each time they asked me to provide test results. I don't know about the rest of the population, but life is too short. BTW can you imagine being without electricity in the middle of nowhere without any electricity ? You can only carry so much gas to power up the back up generator.Can’t connect to wifi and it won’t fully charge SOK batteries