I am not wanting to integrate another battery source into my existing Enphase system, but rather am wanting an autonomous means (e.g., gas generator and/or solar generator (either a portable DIY battery or perhaps a commercial product such as Bluetti or Ecoflow) to power these 8 circuits. Guess, I should have been more clear about the desire to have back up power source that's isolated/independent of my current Enphase system.
As far as Enphase goes, I think the achilles heal with their product are the certified installers/techs. Through my own experiences I find that these guys are unwilling to work on, maintain, or even add equipment to an existing system that they did not originally install themselves. If your original installer goes belly up (my case) then you are kind of SOL.
Thanks for the input!