I decided to not go with an ATS. I went with a manual switch that can switch on/off the AC power running from the 60A breaker in my main panel, and runs over to the Sol-Ark GRID connection. With fear of an inverter failure, I decided to leave my fridge and freezer breakers in the main panel, which is covered by stand-by generator via ATS. Reliable grid power (thank goodness), had a stand-by generator in place long before I knew I'd go with a solar system, so I decided to leave the generator and its ATS configuration as-is (no changes). I figured grid goes down, ATS fires up generator, which powers the main panel, and in effect the AC for Sol-Ark. I have had a couple designers say I took the wrong approach, but my configuration is identical to one of the diagrams in the Sol-Ark manual. I use the setting checked "Gen connected to Grid", and I use "Limited to Home" where my Sol-Ark covers the critical panel, and assists the main panel as much as possible. The idea is, if/when grid goes down, generator fires, Sol-Ark stops sending power to main panel but it will cover my critical panel. I'm okay with that. If grid down was a bad situation (long term say more than 5-7 days), I would probably turn generator off after a day or two to conserve fuel. And quickly move breakers for fridge and freezer over to critical panel. 30 minutes and some wire, and I can get it done. I was trying to dummy-proof my design with an ATS, but the more I read and learned, the more I thought probably best to do a manual switch.
The new 15K and the new loads panel they have, I imagine that would be wiser, as long as the design or configuration doesn't rely on the inverter to keep power going to things like fridge and freezer. I like the thoughts of least amount of equipment (higher reliability) needed to keep things running. I would like to know the grid or generator is there (automatically) in the event the inverter dies which is not what I now have, but I had to make a decision so I went with a manual switch. I just figured it'd be a real crap feeling to come home from vacation to find your inverters software locked up and your food is thawed/spoiled and running into the floor. I wasn't about to take the stand-by generator out of the loop and place it behind the inverter. Plus, the generator is a 22kw and the Sol-Ark can't pass that much power through so it would have been a waste to move the generator in the design, in my opinion. I guess most people place more trust in their inverter than I do, I don't know.