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Batteries alone are not suitable for long duration outages, but solar+batteries, designed correctly, can not only supply enough power during long outages, it can get you to be off-grid entirely in the first place at a dramatically more cost effective number than your $500k quoted - perhaps 1/5 or less for a system suitable for your needs of 115kWh per day. So while the system might be more expensive than a generator alone, it can still beat on value because it provides power all year round.

You also do an unfair comparison here - you are OK with portable batteries providing only fridge & WiFi for a couple hours, but expect whole-hole batteries to last a week. Many people use whole-home batteries to bridge typical outages that last <24 hours, and do so without ever having to notice any change of use of their home - powering their full heating/cooling etc.

Batteries and generators are also not mutually exclusive. You can install a solar+battery system because it makes economic sense and pays for itself while providing zero-downtime backup for most outages, while also backing that up with a generator for longer term edge case outages eg long extended outages during the winter or where there is an unusually long “solar drought” - it really depends on how much resilience you are designing for.

We have frequent power cuts and follow this same philosophy.

Our first line of defence is the solar system's battery. When power goes out, that will keep things running for some time with the big optional loads switched off - e.g. hot tub, hot water cylinder and pool.

If the sun's shining we can run like this for a long time.

In a solar drought, when the solar battery runs low, the next step is to plug the EV in via V2L and use it as a generator to charge the solar battery. EVs have comparatively huge batteries, so at the cost of losing mobility, which may be important in an emergency, this will keep things going for even longer.

One great feature of using an EV is you can drive to a fast charger, charge up in an hour, and transport all that energy back home.

The final fallback is to plug the 2KW petrol generator in to charge the solar battery. This is enough to keep things going forever assuming a petrol supply. A petrol generator is nicely portable and can be loaned to less prepared neighbours who likely have their own petrol.

The key to it all is the solar battery. That gives you uninterrupted power while mucking around with the alternate sources. It doesn't even have to be all that large if you have an EV.

In the scenario mentioned in the GP post where a giant tropical storm hit resetting the grid for 7+ days, how big is the chance that your solar panels installation has survived? Also, if the grid is gone, won’t the fast chargers also be out of service?

Don’t get me wrong, I think you’re right for most cases but I also think for some more end of the world type of scenarios there is little that beats a generator and stored fuel.

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> You also do an unfair comparison here

The comparison is unfair for many reasons, actually. A real install would have solar inputs charging the batteries and offsetting loads during the day.

It also wouldn’t run a 5-ton HVAC system 24/7 for 7 straight days, which is how the post got to the extremely high number.

It’s about as bad faith as the argument can get.

Add wind and I think you are onto something. Where I live it can rain for weeks on end so having another source of renewable is great.
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> You can install a solar+battery system because it makes economic sense and pays for itself

Would take longer than 20yr at current power rates in many US locales.

Highly dependent on where you are, what your electricity costs, and what your backfeeding compensation scheme is (eg net metering). In California solar alone is no longer economically viable with NEM 3.0 but solar+batteries to maximize self consumption is still in that sticky ~7 year layback range - and those calculations tend to assume today’s power prices, that are in reality going up quite quickly.
If you have free night charging plan you can recoup quite faster. My system paid off for itself in 3 years - although I designed and set it up myself, so it was about 3x cheaper than through contractors (and yes I'm in US and I pulled permits to do this).
It's nice to do this for more than just the direct economic costs. The generator doesn't have to run 24/7 since the batteries absorb the excess power produced by the generator. This means less fuel wasted as well as less noise produced. I used to have two small generators that I could run (and team, if needed) but adding a battery component meant being able to sleep at night without a combustion engine burning fuel all night long.
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Will you not own your home for more than 20yr?
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And in some, like ours, it takes 5.