Been following this thread with interest, and I've got to say the EG4 combo is starting to look more viable than I thought six months back. The Flexboss21 seems to have sorted out the firmware gremlins that plagued earlier iterations, and coupling it with Gridboss for grid interaction is clever thinking.
My concern's always been the indoor battery placement — AC Coupling with Solaredge means you're relying on that inverter to handle phase balancing, and if something goes sideways at 2am, you're not exactly popping down to the local supplier for a replacement board. I've been burned before with proprietary setups that turn into paperweights when support goes quiet.
That said, the cost per kWh is getting interesting now, especially if you're retrofitting to an existing AC solar array. The Solaredge integration is less clunky than bolting on a separate battery system with its own separate monitoring app — which is where I went wrong on the boat with a mishmash of Victron and Renogy kit years back.
Has anyone actually run the numbers on what happens when you're pulling heavy loads and the grid fails simultaneously? The Gridboss should theoretically handle the switchover, but I'd want to see real-world logs before committing twenty grand to it.
Also curious whether anyone's hit the thermal limits on the indoor battery. Summer heat in a cupboard under the stairs is different from a proper battery room. Worth discussing?
Would genuinely like to hear from anyone who's got six months' proper runtime data on this setup.