Wow...
I wouldn't use a stepped transfer switch. The reason being...if you have a 8000w generator...are you going to want to install an 8000w Inverter too? And like 2000w of solar? and 16 deep cycle batteries?
It is best to divide and conquer. Our 50A Precision Circuits panel is designed to have high amp items like rooftop air, induction cooktop, engine block heater, electric water heater elements on the Main AC distribution rail. It can also distribute AC power to the Magnum MS3012 Inverter/Charger. The Inverter then passes that along, or if not running on AC supplied from the transfer switch (ie...Shore of Generator)...it will inverter battery power and power the Invert Sub Rail. The sub rail runs a subset of AC components like satellite dish, entertainment system, tvs, outlets, microwave. And the DC system is like it always was. By using an advanced remote for the inverter with ME-BMK and ME-AGS-N...we can tell the generator to run based on voltage, doc, time of day...etc. That was you can manage the generator. The solar just does what it does based on sunlight. No further switching or intervention. It is primarily a DC power provider. SO, there is no need to cascade transfer switches.
You may also look into Hybrid Inverter/Chargers. They can accept more than one AC power source and you can program them to join the inputs to make a larger output.
Not trying to disuade you. I just think you might consider other ways to design the system you want to give you more flexibility and less reliance on users input. It's nice to automate as much as you can, so you can enjoy without constant monitoring and adjustments.
