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.

You don’t need to run your 5+ ton HVAC full time. Get an EV and run the AC there (no more than 3kW). Sleep in the EV. A typical 80kWh EV battery will last several days. And this is not just theoretical; plenty of people have done this.

For Christ’s sake a natural disaster just struck and you want to live like nothing happened? The entitlement is unbelievable.

Assuming you have enough solar, how about running your 5+ ton HVAC system only when there is enough production? And properly insulating your home, of course, using it as a thermal battery of sorts.

If there is a grid outage, surely one can shift consumption to solar production hours while using the battery for the always-on systems (fridge, lights, some computing...).

>I think a simple generator on an ATS remains undefeated from an engineering perspective.

Let me just inject a bit of nuance here to avoid what I think is an unintentional sleight if hand...

For the small sliver of the population that lives under threat of a large area week long blackout in a hot humid climate, I think a simple generator on an ATS remains undefeated from an engineering perspective.

For the vast majority of the population, it's incredibly rare to lose power for that long, and need AC 24/7 afterwards. It basically only happens in the gulf.

> am not aware of any economically feasible way to run my 5+ ton HVAC system full-time on batteries after a hurricane just reset all the infrastructure, and you do need to run it full time because of the insane humidity and latent heat that follows a tropical system.

Which region is this?

Are hurricanes that reset all the infrastructure a recent phenomena in this region? How did people manage in the 60s, 70s, 80s, 90s etc before these rather large (5+ ton HVAC) were even an option?

>Doing the math, I'd need something approaching 800kWh of storage to ride through this kind of event (7+ days)

How airtight is your House? You may be better off with a tighter house to reduce the infiltration load from the outdoor air and possibly section out the house so that post hurricane the primary living spaces are the only spaces that are constantly getting fresh air and there fore humidity load and for the non primary spaces, you dehumidify once and hold it there.

>I think a simple generator on an ATS remains undefeated from an engineering perspective. If you have an air cooled unit

Yes, if your outages are under lets say 10 days a year a generator + fuel will be orders of magnitude cheaper wrt TCO, unless your grid is super expensive.

You average 100kWh of use per day?

What’s 5 ton in new money, 5kW power draw max? Are you planning to run that full power for a week?

Yes, that much in batteries would cost a lot but uk prices right now would be ~87.5k for the batteries themselves (so a shade over $100k I guess). £7k for 64kWh

You’re not going to run HVAC, but I’m more than happy to have the freezer running, the light on the TV etc

Batteries are for load shifting between day and night and for short term backups. Yes, 7+ days of outages do require means of replenishing the battery, whether it's from a diesel unit or a solar. That's not a battery cost problem.

Yeah it's hard for batteries alone to compete with generators, unless we put a lot of weight on things like noise, or are just focused on small loads like fridges.

I think the more interesting comparison is generators vs solar, though it depends on the local weather etc.

I have a 100kwh battery (my car, Zeekr 7x, in Australia). That can run quite a few days or even a week with careful usage.

This is exactly what the post is trying to address: during a serious long-term outage, batteries on their own will run empty. What you need is the ability to recharge batteries from solar during an extended outage, while also flexibly drawing from the batteries when solar isn't enough.

I’ve been looking into a smaller scale option to run limited items medium term on part time hours…

Best option so far involves a mix of batteries that are charged from the mains when available and topped up from a mix of solar and a LPG/multi-fuel generator.

But unless you want to go very large on the solar and generator size it’s unlikely to cover everything full time.

You can run a fridge, natural gas furnace and some lights for a few days on 5kWh (I've done it a few times).

EVs have 60kWh+, which should get you through a week (if not two) easily.

You can run your hvac fan and an oversized dehumidifier for a while off batteries. You don't need the whole hvac system.

I have 18kw of solar and 30kwh of batteries with a 5ton ac it will run it will run indefinitely assuming the sun comes out, if it doesn’t I have a chargeverter that can keep the batteries charged off my RV’s diesel generator or gas portable.

My solar system generates excess power daily and has zero maintenance, the generators are pure money sinks for backup power and require regular maintenance.

Options are nice.

Also heat pump water heater and dryer help reduce load along with efficient variable speed hvac and good insulation.

Fuel is a problem during a storm too and a buried large propane tank is a good way to go but very expensive on top of installation.

An electric car with bi directional charging would add to flexibility either charging from home system or being able to go find power and bring it home.

Ideally I would like a gasoline hybrid with power out like a F150 power boost and a fully electric with large battery and V2L any Tesla would do now as they all have 2400w out I believe Cybertruck can do more. My chargeverter can take 120v or 240v

How about reducing energy use? In general, but then especially after a grid-destroying event that keeps you offline for a week? You surely don't need to have everything HVAC running on full blast in the whole house during that time. And your laundry and next oven long cook can probably also wait until the grid power is back.

If you then add some solar into the mix, it doesn't sound as dramatic anymore.

There is something in between flashlights and a grid scale battery that van power your full electric home.

I just have a plugin battery that I can run the lights, fridges, phone chargers off of for 24 hrs. That is good enough for me, and I think most people. Anything shorter, and it's not necessary to run the rest, much longer, there also isn't because apparently shit hit the fan and we're not necessarily assuming the power comes back on in the next weeks or ever.

> and you do need to run it full time

Or what? Are you made of salt or sugar?

That's a valid concern for you where you are.

For me where I am, things are different. We don't get hurricanes here.

Our longest power outages tend to follow ice storms. We need heat because these things happen in the winter time when it's cold outside, and that's dangerous for various human and infrastructure reasons (pipes freezing and breaking).

But I use natural gas for heat and I don't recall ever having a weather-related natural gas outage. So that's helpful. And ice storms tend to happen when it's cold, but not damn cold -- that helps, too.

My furnace uses about 600W of electricity while running. It does not run all the time. According to my charts on a random day/night cycle last February with a high of -8C and a low of -16C, it was running with an average duty cycle of about 30% over that period.

600 Watts × 30% × 24 hours = around 4.3kWh for that 24-hour period, just for heat.

I'll also need to keep the fridge cold, and some lights running, and will surely be getting some use out of a laptop and some network stuff.

A common-enough home battery size is 48v, 100Ah, or 4.8kWh. They cost around $1,000 right now (some more, some less) in DIY-friendly shapes.

As a spitball effort: If I live more-conservatively and dial back the thermostat (it is a power outage, after all), I can probably get enough power to live a productive, comfortable-enough life on one such 4.8kWh battery, per day. Ish. If I'm careful.

So for batteries, alone, I'm at $1,000 per day. I'll need an inverter as well. That can be either minimal or extensively integrated, grid-tied or not, solar-accepting or not, and etc. Let's just pin that at $3000, with the wiring and accoutrements, and assume I'm doing the labor for free.

I'm now at ~$10k to survive a week of power outage at home in the winter on batteries alone. That's expensive[1], yes, but a whole lot less than half a million bucks. A whole lot less than a very nice, installed, low-RPM generator, too. :)

...except, realistically: It's more like $13k for a week, because future-me will surely not be as careful with energy use as present-me suggests that I should be and 3 more batteries adds some safety capacity. :)

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And that can be supplemented. Solar input can obviously be used (if available), but may be limited by winter sunlight conditions and storm accumulation.

Gas-fired generators can also be used. An inexpensive-ish portable inverter generator does the trick well when combined with, say, an EG4-6000XP do-all inverter.

That particular inverter wants to see at least 2 of these batteries connected, so let's play with that minimum: 2 batteries, 1 inverter, 1 generator. ~1.4 batteries worth of load every 24 hours, as with the safe $13k figure above.

The generator can be run pretty hard (it has a continuous max rating for a reason), and it can be run intermittently. The EG4 allows programming of generator input power.

So let's pick a generator: Champion 201509. It can do 7kW continuous, and we'll load it to 75% of that, or 5,250 W. From this 5,250W, it provides for the house's present consumption while it runs, and it restores the charge of the two batteries to 100% SoC[2].

If it is run once per day, it can do this job in about 2 hours and then be switched off until tomorrow.

If it runs like this once per day for a week, I guesstimate that it uses about 11 gallons of gas over this week. That's a very manageable quantity of fuel.

So we're at $2k for batteries, $3k for inverter+stuff, and $2k for an appropriate generator. That's $7k to run ~indefinitely, or as long as I can keep bringing in fuel, with enough power to survive a blackout (with heat, lights, refrigeration, some entertainment) long-enough on batteries alone for the roads to become passable and then decide if I'm making a run to fill up the gas cans with fresh fuel.

Not so bad for a relatively quiet time of living in a temporary blackout, and the house gains a gains a big UPS for some stuff (which is nice). (The installed gear also offers an easy entry into solar power.)

But I'm not in hurricane country. And while I do love me some aircon, our summers are pretty survivable, usually. My needs are not the same as your needs are. :)

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[1]: Except, for the price of this kind of self-sufficiency: Draining/blowing out the plumbing and staying at a hotel or with friends/family for a few days in an unaffected area might be a better option. The cheap portable air compressor I have doesn't leak down at all, so it's always got a full tank of air while just sitting there unplugged. I'll figure something out: Power outages are very quiet, creative times.

[2]: 100% SoC? Yep. It's a temporary blackout where the batteries are operating as a UPS, not a long-term operation where the typical 20%-80% SoC goals are important for longevity. They won't stay at 100% for very long, anyway.

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Oil generators have an “artificially” low price because there’s a lot of demand for oil for other things. If the other sources of demand go away, the price may become unfavorable even if gas generators make a lot more sense from a redundancy perspective.