I have Enphase iQ7 microinverters, and they do work great, but for off grid, I don't think they are the best choice. My system is a hybrid with a Schneider XW-Pro battery inverter. When it goes off grid during a power failure, I have the Enphase micros AC coupled to it, but it is not completely stable. For the few times our grid is down, it works, but I would hate to depend on that for full time off grid.
The sun is down more than half the time, so I would have at least half of the solar array DC coupled to charge the battery bank. I added 2,000 watts of solar panels with a DC charge controller and I am very happy with the results. That DC power is basically what runs my house all night now. The Enphase microinverters provide my AC power during the day while the sun is up and the DC panels charge the battery for use at night. But like I said, off grid, the micros are not the most stable. I have 16 of them, and 5 of them basically refuse to stay producing while off grid. And several more tend to cycle off and on and the battery does not stay charging. I ended up running at a slight loss the whole time. So for a fully off grid system, I would probably use all DC coupled.
If you have a known shading pattern, you could plan the array around that. Series panels that will be shaded at the same time, and parallel with panels that shade at different times. And you can do panel optimizers as well. When I added my DC system, I thought about the Tigo add on optimizers. I may still get them, but my shading is not a big problem and the array is producing well without them. Another good option is using 3 or 4 separate MPPT charge controllers. That way each group is independently optimized, and if something does go wrong and fail, you still have the others to keep making power.
48 to 12 volt step down DC to DC converters work well, but they are likely only 95% efficient, so you will lose a little power. For things like room lighting, see if you can get 48 volt LED lights, or, if you use 12 volt, put the light switch on the 48 volt side before the DC to DC converter so that you are not wasting power running the converter when the lights are off.
For the 120/240 split phase AC power, there are a lot of inverters out there. I would definitely go with a large low frequency type for several reasons. The large transformer really helps keep the power clean and stable under difficult loads. As much as I like to complain about Schneider tech support and software, the hardware in the XW-Pro inverter is an absolute beast. It will drive any load you can throw at it. The 6,800 watt rating is all day, 24/7 without ever a complaint. And you can pull over 5,000 watts on just one leg without issues. It does 8,500 watts for 30 minutes and surge to 12,000 watts for over 30 seconds. And even with the giant transformer, the idle current is quite low. Easily half the wasted power compared to a Sigineer or Ames of the same power capability. My second choice for an off grid inverter would probably be Victron.
While it is nice to use the matching Schneider charge controllers for the data, it's not required. I am using a cheap BougeRV DC charge controller for my 2,000 watt DC array, and it works just fine. But if I was depending on the DC system for all my power, I would probably move up to something like Midnight Solar, Victron, or Outback.
The EG4 batteries look good. Don't cut it close. However much battery you think you need, add 50% to 100% more and don't cycle them as deep. Yes, it will cost more up front, but if you only cycle 40% instead of 80%, they will last more than twice as long, so it does end up cheaper in the long run. I started with 18 KWHs of battery. It was "Enough" to just cover the high rate evening time, but on my first real power failure, I had to run it down to just 20% remaining. I doubled my battery bank to 36 KWHs and now it is normally staying over 55% and after a few days of clouds and storms, it only goes down to 40% running the house all night. And also only charging up to 85 to 90% is easier on the cells as well, and the C rate is also reduced for the same charge power. Since this is a new build, it may be difficult to get a good estimate of how much power you are really going to need. 6,500 watts of solar panels could easily make over 30 KWHs in a good sunny day. It would be nice to be able to store it all instead of having the charge controllers throw it away. If the car will be home during the day, you may be able to have the EV charging to use up the power without having to store it in the house battery first.
I am sure you will have more questions and others on here should be tossing in their ideas as well. I am not trying to tell you what to do, just giving my thoughts.
