Monitoring 27kw Generac Generator with Raspberry Pi and Multimode Fiber
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I have a 7kw portable generator that will run on Gasoline or NG, but I wanted the entire house to have power no matter what
I monitor and automate the whole shebang using a venusgx, mqtt, rpi with openhab. Touch wood, two years without anything exploding.
Other nice element is that the inputs are agnostic, so hydro can run in parallel - and I can do nanogrid coupling with frequency shifting for the more remote wind inputs.
Obviously a different use case to you, but the idea of having a single and expensive point of failure doesn’t sit well with me.
It works great, and I hope will be low/no maintenance for years.
But I'm under no illusion that anyone else will be able to do anything with it should I shuffle off this mortal coil.
Using one big genny in a straightforward way is a sensible call for a vital infrastructural component IMO.
As they say, Keep things simple because fools are very ingenious.
The air cooled ones are not as nice
Why though? Do you live somewhere with unreliable electricity?
Says you. But who are you to tell someone that can afford the lifestyle to which one has become accustomed to be sustained under any circumstances?
(*) Externalities not included
4000 sqft house with high humidity 90 deg summer days (so anywhere in the SE US) will need at least 8-tons of AC, so 2 units, and that's ~24kw right there if you need to cool the whole house.
But the more common practice is to run just one of your two units and then have plenty of room to run all the small wattage things in the house without needing to actively budget power.
Having lived through more than a few week+ outages in Jul/Aug/Sept heat (including 3, 6, and 8 week outages), I certainly see the value if you can afford it.
Comfortable, but not necessarily extravagant.
ETA: We also learned our lesson relying on NG and converted to dual fuel with a 2-week supply of propane.
Even deducting $25k from that for the cost of the generator and another $10k in required electrical modifications, that would more than double electricity costs (vs the grid) based on 20-yr lifespan and payback, before interest.
A big generator won't stall if your AC kicks in at the same time you have the oven on, or something similar.
So if you have regular outages, I can certainly see the appeal of a 27kw generator.
FWIW, pulling can be easier. Put a cotton ball on the end of a light string and grab a vacuum cleaner onto the other end of the conduit. Very fast.
Also, the next size up of conduit doesn’t cost much more. Unless you are some sort of professional conduit sizing engineer optimizing for material cost, always get the next size up conduit from what you think you will need. Pulling is easier and you might change your requirements later.
As for outages, wouldn't a UPS be sufficient?
Being Dutch, this does sound a bit like overkill.
Most times I see an electric generator like this in the Netherlands is at festivals, or on the national news where a remote 100% renewable museum couldn't get hooked up to the nation power grid due to lack of capacity, and had be powered by diesel generators.
In the last ~12 months, I've thrice lost power for more than four hours. Once you start losing a fridge's worth of groceries every 4 months, amongst the other challenges with power outages, the at-home generators start to look attractive.
On the other hand, 27kW is a LOT of generating capacity for one home. I consider that the average home (at least in my area) only has 200A service, and I don't think I've ever heard anyone complain that it's not enough (outside my dad who wanted a 16-person hot tub for two people).
Uh, a 27kW generator is 225A at 120v, it’s the model you use if you want whole-house backup generator for a 200A service…
https://www.generac.com/generaccorporate/media/library/conte...
During active loadshedding we can expect multiple 2-4 hour outages during the day. UPSes dont work because the batteries are destroyed after a couple of sessions. Proper battery based backup solutions are prohibitively expensive for most.
Most upper middle class households have backup generators installed, usually 4-7kW. If you can afford it, you install a full solar power system, allowing you to disconnect completely from the grid.
We don't have gas, oil furnaces or other sources of power (other than solar for the wealthy as explained above), and for most our hot water is made with electricity.
The unreliable grid has become a fact of life for all south africans, and we have adapted according to our means, all the way from a fully independent off grid solar soltion for the rich, down to candles for the poorest of poor. I keep candles in my cupboard in case my backup system fails.
Though 27kw is a lot. They’re on natural gas too, so I guess they’re not worried about running out of diesel (though nat gas can be another point of failure)
27kw is decent size depending on size of house.
Re: the article - does the setup give more functionality to the smart transfer switch capabilities?
https://www.generac.com/generaccorporate/media/library/conte...
Being dutch you won't have CH4 shortages this winter (unlike what the EU might face). You'll supply your own industry, power stations and homes first and then your gas clients. You also only have one real natural disaster to optimize for, flooding. Europe has incredibly mild weather compared to the rest of the world.
Add to that that your infrastructure is newer than N. Americas - it all got rebuilt after WW2. The supply cables into my old house were 100 years old.
Finally, there is heating. Most homes need some form of an electrical motor for their heat (either as a blower for the furnace or a pump for their radiators). Consider how lucky Europe is climatically: the Netherlands is 52N. By comparison, Toronto is at the same latitude as Nice - this is due to the Gulf currents. Pipes in the Netherlands will not freeze if you spend a few days without heat. The pipes in the homes in the upper half of continental US will burst after a few days without heat.
Finally, generators are not particularly bad for CO2 emissions or other pollution compared to the grid. Not when you consider their low usage. We can afford them, they address real problems, they're fairly benign, so why not?
EDIT: clarity
-Canadian expat.
My friend lives nearby and has a whole house generator. Uses it 2-5 times per year. It's funny at night when he's the only guy in the neighborhood with his lights on.
Runs on natural gas.
I wonder if the author could shed some light on the reasons for this technical choice though, because my back-of-the-envelope calculations just don't end up with this kind of tech.
The Generac is about $13000 excluding install. A Tesla Powerwall+ $11500 installed without subsidies.
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, but not by a lot. I realise residential power consumption may be higher in the US, but probably not by an order of magnitude.
A popular home battery, the Tesla Powerwall does 13.5 kWh. That's 2.5 days already without any solar. Add enough solar and you've got basicly unlimited backup. In a single family home with a garage, one can also easily add vehicle to grid for extra emergency storage.
Friendlier to the environment, lower maintenance, cheaper. Unless one consumes over 7 kW continuous or 10 kW peak in an emergency situation.
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
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...
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.
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.
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:
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.
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...
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.
> A diesel generator is by far the cheapest way to generate that much power.
Natural Gas generators (like the OP’s) are much cheaper.
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 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 went with the 26kw air-cooled model, and getting that installed along with a 1,000gal propane tank (and 800 gal of propane) was done for $18k.
Our biggest load is HVAC, to run two AC units (5 ton and 3 ton). During an extended outage, we'd shut down half the house.
Must not read the news much, but there are all sorts of things that cause people to be without power especially weather related. However, since you're claiming that the Dutch never loose power for more than minutes at a time, perhaps we all should consider relocating.
I hope the authors system makes some cool and useful charts :)
Dang, we are still geeks.
they do have a "cloud" option but that requires additional device purchase and a subscription service. shit.
i would love to integrate it with a home-assistant network at home but till now nothing. good thing this generator had a linux app otherwise it would've been like my case
In my house I had a tesla powerwall installed (yes I know, rich prick alert) the gatway has some shitty wifi that cant be disabled, and kneecaps the range of my house wifi, because it insists on using the same channel.
The back of the house can pick up the AP in the garden, the top front not so much. So a bunch of things are sporadic now.
tldr:
Wifi is fine until its not. Hardwiring for critical path stuff reduces a hard to diagnose mode of failure.
You could also tape some antistatic bags together around the power wall box to act as a faraday cage, and throw in a Pi acting as a wifi-to-Ethernet bridge into the box or inside the f cage to get a wired signal out, if the interference is really that bad.
I think much of the difference is the above ground electricity cabling, forested areas, and just the economics of providing service to a large geographic area.
if you live in the suburbs of a city like seattle which I wouldnt call having super bad weather its pretty common to lose power for a few days every year due to power cuts - it gets annoying and if you can afford it, why not install a genny.
Do these generators auto-start when the power goes out? Do they auto-stop when it comes back on? Do they do automatic weekly self-tests/diagnostics? How clean ('true sin') is the AC output? For the portable ones, are they multi-fuel?
Oh, and don't pay 'list', go for a 2nd hand one otherwise you'll end up negating all your gains, in the industrial world nobody pays list except suckers.
Why oh why the multimode though? Single mode all the way.
Any length of wire between two electrical ground points might, if there's a lightning strike in the vicinity, be subjected to huge "ground surge" currents. I buried 25 pair copper in a conduit and saw it vaporized; both ends of the conduit run belched flame and smoke and molten bits from a lightning strike that wasn't that close (half mile or less), and certainly not direct.
My experience says that a free length of wire grounded at a midpoint (like when you disconnect the far end) will still be a potential resonator for enough volts to cross a respectable gap; so unplug it and insulate the unplugged end. Been there, seen the sparks.
I maintained various configurations of wire and fiber across a 1/4 mile run through heavy woods on a ridge that gets direct lightning strikes a dozen times a year. nothing involving a conductor that length is simple in that circumstance: see the things the power companies have to do.
> I maintained various configurations of wire and fiber
Separately or at the same time? What was the wire for in your case if you had it parallel to the fiber, and what did you do to protect it against the lightning strikes? We have it between two directly adjacent buildings that are maybe only 150ft apart (mostly underneath an asphalt access road) but there are no lighting strike rods/redirector on either structure.
Upgraded that to coax Ethernet as soon as I could, 3c509 cards in cheap linux routers at either end of the link, with "modem failover" until the incident that blew away the 25pair. Those cards would lose one or both with every other storm it seemed; but were ~$2/ea off ebay at that point so not so bad. I've got at least one of those motherboards still, somewhere, with multiple bodge wires where i repaired traces blown off by lightning strikes.
When we got the fiber we buried the first run, with coax beside it, in conduit again. That lasted a few years before a "landscaping accident" tore out enough that there was no fix. Then we went to suspended coax, and then another fiber tied to that, for a few years, before the business folded.
I tried various grounding strategies over the years. The power companies and "best practice" suggest regular connections throughout the span of the line, and at both ends. I found that seemed to invite strikes by being a very good RF ground in the air.
Grounding at both ends is bad because of ground surge, pick one or the other end and have the best ground point there you can get, but let the other float, and hope. Also, any actual power system imbalances between two ends of a grounded line will seek to use that nice conductor rather than the cold earth.
150ft isn't that far. Also you haven't got trees to complicate things, they draw lighting and ground it deep. Hickory trees were my bane; they got deep roots that found our high iron sandstone layer and combed the sky for electrons. I'd say consider the switches at either end of that link to be sacrificial buffer parts, and not really worry about it. If its worth considering running fiber under a street, it might be worth considering a free space laser link or something.
I do understand why you would want to leave an end floating but I'm not sure to what extent that is possible since ground surge voltage is probably enough to jump from the cable shielding to the inner twisted pairs, and so you're always going to have some grounding on both sides (via the switch fabric through to the mains), but I guess all you can do is make the alternative grounding path lucrative enough; if it's a short run and you have a nice, fat ground on one end, hopefully that should direct the surge away from the skimpy 20awg cables grounding it on the other end.
That said, surely it would also whack everything through the mains connections or gen feed if that was the case? shrug
Lightning is like 300,000,000 volts. No surge protector is strong enough for that.
Back in the dialup days we used to lose a few modems a year to lightning, our computer didn't explode into a ball of fiery doom. (and the ancient phone would ring for a fraction of a second and you'd think "shit, I forgot to unplug the modem, there goes another one".