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Author here. It was $20K installed total

I also have 17kw of solar on my roof, and overproduce. I have 1:1 net metering, so a battery will not help financially unless that ends. the only utility a battery provides is backup power

In the middle of summer I will use around 80kwh a day with lots of AC usage (Yes, I could get more insulation, better ducts, switch to minisplits. all in progress)

A lot of that is at night, because it doesn't get any cooler at night really. It still stays hot and humid. Between sun I'm using around 30kwh, so I'd need 3 x Tesla Power Walls JUST TO MAKE THE NIGHT and hope it was sunny the day before to fully charge, and sunny the next day

The cost for that is over $30,000, only makes the night, and still only outputs around the same as the generator. If it's not sunny but it's still warm, I'll be without power in a short time. If I'm spending that amount of money, I want power to stay on no matter what

I'm waiting for Enhpase or Tesla, or someone to come out with an AC Coupled grid tie battery that has full generator support. That is the dream. Then in low solar days it could pre-charge the battery with the generator for night time. I don't want to drop a ton of cash now, when that is surely on the horizon. Either that, or the ability to use a car as a battery. If I could use a Tesla as a battery, I would probably go buy a 100 model Tesla. That would be 100kwh! much better

> Either that, or the ability to use a car as a battery.

Not sure if it fits the bill for you, but the new Ford F-150 lightning can supply 9.6kw of continuous power:

> With the ability to offload 9.6 kilowatts of power, Ford Intelligent Backup Power keeps the lights on during an outage while providing security by powering home appliances, security systems and more

Ref: https://media.ford.com/content/fordmedia/fna/us/en/news/2021...

I think what's driving a lot of the questions is not knowing how much instantaneous power (and startup current) your AC uses when it's on. 80kWh/day is only 3.3kW avg, but assuming most of that is your AC (with 30% duty cycle) and it seems your system is at most oversized by a factor of 2. There is a 22kW model in the same product line, so presumably you had a good reason to go with the next one up.

Given that Texas's electricity problems involved a problem with the natural gas supply, are you not worried about that going out as well? I just got a generator, but aimed for a small one that would be more efficient so that I would need to store less fuel. Although I still need to figure out some solution for intelligent load management so that I can run (fridge,freezer,boiler,etc) sequentially rather than simultaneously.

The 22kw is $500 cheaper than the 27kw, no point going for the 22

> I'm waiting for Enhpase or Tesla, or someone to come out with an AC Coupled grid tie battery that has full generator support.

Enphase either already supports this, or is very close. Their current gateway device (smart transfer switch) for their Encharge 3 / Encharge 10 AC-coupled batteries has connections for a generator and I know the installation manuals on their site describe what kinds of generators are supported and how to wire them up. If they don't officially support that configuration yet it's only a matter of time.

Speaking of HVAC on a generator - have you heard of the Hyper Engineering SureStart devices?

They put less stress on the generator and compressor when starting up. I got them installed on both of my AC units, and they work great on the generator, and the generator doesn't bog down when they start.

https://www.electricgeneratorsdirect.com/Hyper-Engineering-S...

This video is illustrative:

https://www.youtube.com/watch?v=ApscKchMybM

Yes! I have one. It lets me start my 5 Ton AC on my 7kw portable generator without issue

Until now I felt bad by consuming ~ 10kWh per day on average, now it is more clear why the climate warming discussions are a waste of time.

If it helps, I have solar and overproduce so I'm net negative on carbon for electric at least

Humidity is indeed the problem! You can live with dry heat but humidity just makes it hard to breathe and it’s such an oppressive, overwhelming presence. And it’s expensive to dehumidify a room via any of the conventional means.

If this is a Texas install, then the house could be running upwards of 5 tons of HVAC capacity. This is a monster load that is very unusual outside of southern US states.

Getting through a hurricane is a lot easier when you can pull humidity out of your house the whole time. Running this much cooling on 1 powerwall would take you about 4 hours before you are in the same boat as everyone else. In many cases you need to go 72+ hours non stop. Gulf coast does not cool down that much at night after a cat5 blows through. It's practically unsurvivable in some cases.

> The electric power consumption at our place is under 5.5 kWh per day on average, with very few peaks.

That's why your back-of-the-envelope doesn't necessarily add up with the author's.

In the US South (at least where people run AC) it's entirely possible to use 24 to 48 kWh per day. There are big, fancy houses people own that could double, triple or quadruple that.

http://shrinkthatfootprint.com/average-household-electricity...

>the Tesla Powerwall does 13.5 kWh

One liter of diesel, costing a few of your local currency, stores 10kwh.

>Add enough solar

At enormous cost

>my back-of-the-envelope calculations just don't end up with this kind of tech.

That's because you have erroneously conflated several different variables. A diesel generator is by far the cheapest way to generate that much power.

I was with you up until here:

> A diesel generator is by far the cheapest way to generate that much power.

Natural Gas generators (like the OP’s) are much cheaper.

> The electric power consumption at our place is under 5.5 kWh per day on average, with very few peaks. Slightly less than average for Belgium,

That's an average of about 230 watts. How do you get that low?

An idling iMac with Intel processor is around 70 watts, according to Apple. My refrigerator is suppose to average about 50 watts. That's halfway to your usage right there. In the summer, when I don't need heat, I usually have a box fan in a window to circulate air, which is another 50 watts. Add another 10 watts for my cable modem and router. There's probably another 20 watts total for various other things like TV in standby, a couple of smart speakers for voice control and music, and network switches.

So that's got me to 87% of your usage just from things that are happening all the time when I'm not even doing anything! (Oh, and there is an outdoor security light that comes on at night. I have no idea what its power use is (or even what technology it uses [1])).

Then there are the things whose power depends on what I'm doing. Microwave and toaster oven once a day to make breakfast, and sometimes to make other meals. About 40 minutes walking on my treadmill. Electric pump at my well to supply my water. Electric lights. Electric water heater for my hot water. I also actually use my computer and my TV at times, so they are often using quite a bit more than idle or standby power.

That's got me way over your usage on an ordinary day when I'm just doing my daily things. Looking at my records, the lowest I've gotten down to is about 12 kWh in a day, which I can hit in summer, although average in summer is a little higher due to things like an electric washer and dryer that I typically use a little more than once a week, and an electric dishwasher used a little less than once a week.

The internet tells me that about half the households in Belgium have natural gas. Are you doing with gas some of the things I do with electricity, like water heating and cooking?

[1] Seriously, I have no idea what the heck it is, except that it is not LED. It has been there as long as I've owned the house, running every night. It has accumulated at least 50000 on hours since I've been here, which is quite a bit longer than the expected lifetime of every kind of bulb I've found that otherwise looks like it might be the same technology.

> That's an average of about 230 watts. How do you get that low?

That's not considered low here. That's slightly below average.

> An idling iMac with Intel processor is around 70 watts, according to Apple.

We don't have desktops idling. We do have an old thinkpad with the screen switched off running as a home server. We use laptops plus two large screens.

> My refrigerator is suppose to average about 50 watts.

No idea of our consumption. I just chose one of the less energy consuming freezer/fridge combinations.

> In the summer, when I don't need heat, I usually have a box fan in a window to circulate air, which is another 50 watts.

We have heat recovery ventilation.

> Add another 10 watts for my cable modem and router.

Fritzbox dsl modem with builtin basic routing.

> There's probably another 20 watts total for various other things like TV in standby, a couple of smart speakers for voice control and music, and network switches.

No TV. One additional network switch, and a printer in deep sleep.

> Microwave and toaster oven once a day to make breakfast, and sometimes to make other meals.

Microwave, toaster, cooking hobs, oven, water cooker. All relatively simple appliances here. The cooking hobs are inductive. That saves a bit of energy.

> Electric pump at my well to supply my water.

We get our water from the city. No well pump.

> Electric lights.

All LED.

> Electric water heater for my hot water.

This is really the big one. One 24 kW flow-through natural gas heater.

> an electric washer and dryer that I typically use a little more than once a week, and an electric dishwasher used a little less than once a week.

We use an electric dishwasher very often, at least every other day. It's a fairly energy efficient one. Clothes we usually dry on a rack, though we sometimes use a dryer. Fairly energy efficient one, heat pump based.

I also run around 6kWh/day. Natural gas for heating, hot water, stove (but electric microwave and oven). I run a mini-itx Intel i5 server 24/7, a PS4 constantly I standby, a bunch of ESP8266 smart plugs and sensors, a projector in place of a TV (I think it uses 500W when it's on). No dryer, no particular effort to reduce electricity usage beyond what I was taught as a child. Three people (one of which working from home) and a bunch of pets in a 110m2 house.