Variable Frequency Drives (soft starts) allow smaller generators to get through Locked Rotor like the starting current for an HVAC. However, I know they are expensive and I don't know if companies that provide generators sell the unit as an option.

VFDs generally only work on 3 phase motors. There are soft starters for Air Conditioners which cut the starting current in half.

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My experience with VFD's has been only with three phase circuits. I thought because they are so useful in those applications that some company would make them for 220 volt single phase use.
Even though they might be expensive, they got to pay off. I mean... if you only need 10kw for your connected load but have to have a 15KW generator just to get past the starting current...
Well, that is a lot of fuel being consumed for no reason. I think.

These guys make single phase VFDs.

https://www.ato.com/5hp-vfd-single-phase-input-output

I would love to try to implement one for a house air conditioner. The issue would be setting up a programmable thermostat to work with it. It has RS-485 capability, so the programmable thermostat would have to be able to send RS-485 or a 4-20mA setpoint. It would need an RTD with a 4-20mA output.

Good luck. What you just posted is a little over my head.
I know you could do it. Nothing wrong with investigating.
Heck, use my house for trials.
My 9KW doesn't like starting up my roof top compressor.

Rapewta: Install one of the soft starts and I expect it will work.

I vote for Kohler

At this point I've figured out the transfer switch answers I need. In the mean time I set up a power inlet on the outside of my house going to a duplex receptacle inside. I tested running the refrigerator with the gen. (Honda 2200i) on gasoline. The engine speed goes up and down as the refrigerator compressor is activated. All seemed to work fine.

I ordered the Hutch Mountain kit to make the gen. tri-fuel. I installed the parts needed to run on propane and it fired right up.

There are a few comments I have on the Hutch Mountain conversion:

1 - Tuning - they say turn the screw in approx. 5 turns or until the engine starts cutting out - then turn back 1 full turn. This implies the regulator is shipped to make the engine run rich. I performed the "tuning" and it seems to run very smooth but I haven't loaded it. Any comments on running rich or lean or ?.
2 - I think the kit is okay - the instructions are so so IMO. I took the hose off the air cleaner on the air cleaner side. The other end (per the manual) did not disconnect easily on my unit.
3 - The fitting on the top does not easily allow tightness to the plastic and desired orientation at the same time. Probably could put additional washers on to get the result you want.
4 - The orientation of the gaskets is not fool-proof. I was a fool and didn't figure it out immediately.

Anyway if there are Hutch Mountainers out there that want to comment great.

Of course this now guarantees we won't have an other PSPS covering my area.

Thanks.

In So Cal, looking for natural gas and either propane or gasoline dual fuel. To no avail. Must be some technical reason that I'm not aware of.

My thinking is that despite the many earthquakes we've had in my 50+ years, we've never lost natural gas service. But I also keep a lot of propane on hand for patio heater etc. so that would be a good backup. Anyone know of such a beast?

ps Sorry about the hijack

The Briggs & Stratton home generators are NG/Propane. You do generally have to switch a valve to change the setting.

Great - thank you both!

Please see my note above. Conversion kits are available from multiple companies. For example - Honda does not at this time offer an official conversion for the 2200i series of generators but as mentioned there are a number of kits out there for that model. I converted my new Honda 2200i and it seems to run fine but I haven't tested it with a significant load over a long period of time. I did the conversion to avoid running into stale gasoline gumming up the works when the power is shut off e.g. 2 years from now. Propane stores for a long time in the bottle.

As mentioned above, B&S does sell NG/LPG dual fuel generators. Kinda pricy ($3500 for 12Kw) but I am interested nonetheless.

https://www.homedepot.com/p/Briggs-Stratton-12-000-Watt-Automatic-Air-Cooled-Standby-Generator-with-200-Amp-Whole-House-Transfer-Switch-040626/311721244

There are no whole house generators that are "inverter". They have quite decent frequency regulation.