I 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. Doing the math, I'd need something approaching 800kWh of storage to ride through this kind of event (7+ days). This is approaching half a million dollars in batteries. I can install an extremely nice 1800 RPM generator for ~15% of this cost, which would also include a year's worth of propane buried on the property.
I think a simple generator on an ATS remains undefeated from an engineering perspective. If you have an air cooled unit, the maintenance is not much more complicated than with a lawnmower. You just have one extra spark plug to deal with, and sometimes the oil pressure sensor needs replacing. I can get my stubborn Honda generator to start with all kinds of weird tricks. If my Ecoflow battery starts to act weird, I have very little recourse by comparison.
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.
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.
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.
Would take longer than 20yr at current power rates in many US locales.
For Christ’s sake a natural disaster just struck and you want to live like nothing happened? The entitlement is unbelievable.
I’d still have to deal with wheeling it out, and doing periodic oil changes. Not sure how/where I’d want to deal with a 200lb unit… A natural gas unit would be more practical - I don't have gasoline yard tools.
I could get a transfer switch installed and use my house’s main AC unit. The cost of the larger generator isn’t that much more and I wouldn’t need a window unit and lots of cords.
Of course, then I could skip the portable unit and get a whole house generator with automatic transfer switch.
It’s hard to put a finger on it. The “cheap” solution doesn’t seem worthwhile while the others start making me wonder “how often does the power really go out”? It all seems silly for 3 days outage once every 5-10 years.
The desire to operate a massive AC just after a natural disaster is just unhinged. Similarly, this idea that your life should be able to continue as before, your neighbours be damned, is also psychotic.
People like me push for the better solution (against great opposition) - neighbourhood-level improvements so the rich don't hoard all the resources while the rest are left to die.
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...).
If there are clouds lowering solar output the ac isnt running as much either or at night.
If I wanted to run as though the grid was up would probably need double the size solar and battery.
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.
In the spirit of nuance, the vast majority of the population of Florida is at risk. Something like 10% of the US population in total could be impacted directly. You don't actually have to live on the coast to get rocked by a hurricane. Ike took out power for millions in Ohio.
https://www.facebook.com/100044470387919/posts/ohio-remember...
I have an EV which supports V2L (20A/120V). Even if it supported V2H, I'd want to save the battery for driving.
Our backup power is a 9kW gasoline generator, with a manual transfer switch.
I've lost power for weeks from snow, wind, storms, and ice, living in the central midwest and mid south. We lose power almost every time it rains in the spring and summer for many hours.
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?
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
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.
I think the more interesting comparison is generators vs solar, though it depends on the local weather etc.
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.
EVs have 60kWh+, which should get you through a week (if not two) easily.
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
If you then add some solar into the mix, it doesn't sound as dramatic anymore.
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.
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.
It's just a bit of temporary[1] redundant local infrastructure that is hopefully never used at all, and when it is used it won't be used for very long. The fuel will remain available for as long as any of us reading this are alive.
The price of the fuel may go up (it probably will go up), but it doesn't really matter much at this scale whether it costs $25 per day to run or $100 instead -- the power grid will come back online soon enough.
[1]: It's a backup generator, not an heirloom. In 50 years, people will look at that old thing and laugh at how interesting its archaic nature is. They might tinker with it. They might give up and have Jeb haul it off as scrap. And that's all fine, too.