Backup power - Generator vs Battery

It's been my experience that most folks know next to nothing about POCO policies and NEM details and make even less of an effort to find out what they get themselves into.
Add to that the POCOs seems determined to intentionally make no reasonably easy way to make the labyrinth of policies (which policies they blame on government regulation) even remotely understandable without a lot of time and effort.

Our local energy company pays 0.197 per kW. We have banked $400 since mid-May when our array came online.

My problem is that we made a lot of infrastructure upgrades just as the solar went in, and I don't have a baseline on how those impact the electric utilization while we were 100% on grid. One upgrade was swapping a failing oil-burning HW tank for an electric heat-pump tank. That went in just before the solar came online, and we did not see any increase in grid usage from that time frame over prior year. Shortly after, we upgraded out oil furnace to an electric heat-pump as well. On energy usage, I have calculated that the house is using less electric, but it's still a frickin' energy hog. When you turn on the electric oven or electric clothes dryer, and watch the home consumption icon on the app spike up...let's just say I am learning to be far more conservative and less cavalier with how I cook and do laundry.

Natural gas is not an option in our neighborhood, and I will NOT have propane run into the house.

Recently the operators of a historical property decided the electric bill
was too high, so they did a knee jerk reaction of changing all the bulbs
to LEDs. Since most were off most of the time, this had little effect.
Later I was able to show, the consumption was centered around 2 ancient
air conditioning units. And suggested the 2 rooms mostly used be serviced
by a mini split HVAC, the main AC unit only be engaged for certain events.

So to deal effectively with these problems, it is necessary to identify specific
loads and put numbers on their use. That took a couple years of spare time
here in 3 buildings. The annual heating, cooling, and electric use amount to
around 26,000KWh, which is covered by solar generation.

Measurements showed that the half century old electric range, used by 2
people, used less than 1/2% of my energy. Sure the peaks were high, but it
was turned off the vast majority of the time, energy = power X time. I even
found, the microwave clock used more energy per year then the cooking
cycles. That got fixed later.

So get numbers, then make an effective plan. This place is far from state of
the art. But the biggest energy offenders were addressed, and the rest were
dealt with by enough solar panels. Backup is for the fridge and freezer, and
occasional use of the well and furnace. The 4.5KW gen set was bought in
the previous century, has not been actually used in decades. Bruce Roe

Our states POCOs went from true net metering with no limits on KWhrs stored and 1 to 1 sales and purchases to a new program that was far less attractive. The utility has a summer rate and winter rate and the winter rate is much higher. The new net metering rate converts KWh sales to dollars by paying effectively a discounted rate (set by the state PUC). Rather than building up a KWhr surplus during the summer, the surplus is converted to dollars. Then in the winter when the surplus is drawn down, the higher winter rate is used to subtract surplus dollars from the surplus account. Due to this change the residential solar market has flatlined with national firms pulling out of the state and smaller speciality firms closing. Most of the activities have shifted to solar farms for schools and institutions or community solar that have different economics.

Luckily my current systems are grandfathered but my new house will be under the new system and I have to think hard how to work my solar. Ideally I find a battery that I can charge up int he summer and discharge in the winter but to date there is nothing in a residential scale to do this. I suppose I need to use and electric winch to move a boulder up a hill and then generate power in the winter letting is come back down

Redux Flow Batteries can be used for long term storage but require a lot of space. Google up the technology. I think Germany recently came out with a modular system about a 20ft container size that stores 50 kWh. google VoltStorage.

My POV.. I would put in both battery and a 3p genset. Battery acts as an online buffer for short runs while the genset with an easily refillable large gas tank acts as a backup for long periods where we cannot recharge the battery.

I'd consider propane for a generator.
The economics/fuel cost are often similar for propane vs. gasoline with probably fewer fuel storage considerations for propane.

Propane, diesel, gasoline.. whatever works that can be easily transported from source to home. I would consider how easy it would be to get in times of crisis. I have a gasoline genset because if worst case scenario, I can always siphon out of the cars for emergency. Propane or diesel may not be readily available in emergencies.

As for easy transport to an end use, call the propane co. for delivery. If they're closed, gas stations will probably be closed too.
In times of crisis, power may be out all over. Gas pumps need electricity to run.
If an emergency lasts longer than a residential gen set can burn through 200 gal of propane, I expect there'll be bigger problems than power to worry about.
Besides, who says gasoline supplies will be more readily available ?
Also, there are often, and for good and sane reasons, municipal/building code restrictions on large gasoline storage tanks. Residential propane storage is a well-developed and accepted reality for all-weather long-term storage that gasoline storage doesn't enjoy.
I'd be careful about siphoning gasoline out of a vehicle I didn't own. Besides, if you're doing it, it's probably under some emergency duress. If so, what makes you think you'd be the only one doing it ?
I'd take my chances w/propane and if you're paranoid about storage capacity, get a 500 gal. tank and keep it topped at close to the 80% volume limit.

The firm I was working for got approval and big subsidies to install to zinc based flow batteries for hospitals in Mass. The subsidies popped up "overnight" and it was a goldrush to secure slots so I spent a lot of time working up projects to fit these units into old electrical systems tied into CHP systems. Lots of promises out there by the vendors but at the time it was obvious they were mostly early stage Ventre Capital companies trying to sell product that really was not ready for primetime. By the time it was ready to get final approval for the two projects, the flow battery vendor had gone bankrupt. When we checked with the other firms with similar tech they were all gone also.

Here is the zombie website from the company, looks and sounds great until you notice the dates, last updates were 2016.VIZN Energy Systems | About Us

Google Redflow from Australia.

I have 12KW gas/propane dual fuel generator in case we loose power for a few days after a hurricane. I purchased it a few years ago and luckily I have never had to use it. Even though I have not used it but I still feel it costs less then any battery system that can produce the same kWh it can in eight hours.

Let's hope we all never had to use. Ive had to use my genset only once for 8 hours ish when i was having rewiring done but thankfully never had to use for any crisis. One of the drawbacks of ICE gensets however is the need to run them once a month to keep the internals lubricated and top up the battery.

True. But using propane does not have the same gunking issues that gas has on the carburetor. So even though I do run it a few minutes (under load) once a month it always starts up immediately.