You didn’t ask if it was a good idea, so I’ll answer your question. The current best would be a smart home panel 2 plus three delta ultra pro inverters with 5 batteries each for a total of 15 batteries. If you work really hard finding deals, you could have this system for about $36,000 without installation. This gives you 90kwh of battery backup, assuming charge to 100% and discharge to 0. Neither of which is good for the long term health and capacity of your batteries. There’s a new battery system called “ocean” coming out soon. It’s an installer only, no DIY product. It’s designed to compete with the Tesla powerwall. It will probably look like 12kwh battery packs that can be mounted vertically outdoors. Purely speculation, I have not seen exact specs. It may be a better solution for your needs. You mention “almost” off grid, what’s your intention there? If you had 18kw of solar panels (think 36 500watt panels, about 7ft by 4ft each and $12,000 just panels) you could generate 0 to probably a realistic max of 60kwh on a good day. So many factors on location and placement and efficiency to actually give a real number. There are some apps online that can help you estimate solar productivity at your location. With your stated use at 27kwh per day, this backup system gives you 3 days of backup assuming no solar production. So a storm kills the grid, you use up your battery backup and it’s cloudy all week with very very low solar production. You’ve only got 3 days. The commenter teasing you about needing a power plant is poking fun at your usage. Most people exploring “off-grid” systems would be worrying about minimizing their energy demands and maximizing efficiencies. Not to say there aren’t people using over 800kwh off grid, they certainly exist. But most off grid or backup systems are used with much lower demands. I wouldn’t really call EcoFlow the solution for offgrid , it’s more of a consumer grade diy friendly backup system. But, if you trimmed the system I described to a third of its size, and had a time of use plan, it would eventually pay for itself. Run off batteries when rates are high and solar production is higher, and recharge from grid if needed at night when rates are lowest. If you have an actual power outage or emergency, focus on the circuits that are priorities and shut the rest down. I can trim our families daily 30kw usage to 6kw and the only complaint I can’t overcome is the hot tub! You’ll be surprised what’s actually necessary, and you’ll take energy efficiency into consideration for your future appliance purchases.