$912 energy independence without red tape
sunboxlabs.com
sunboxlabs.com
A 3kW inverter powering a fridge through extension cords (fridges/compressors can have serious inrush current). You can't just snake "yolo" cables through a house for anything drawing serious amps (say, more than 5).
I'm willing to bet zero impedance or insulation/continuity tests were done. I hope the inverter has the RCD protection included.
This "works" 99.9% of the time. Now multiply 0.1% by every person who sees this and thinks it's a clever hack.
Update: He's plugging an extension cord directly into the inverter's output terminals? A 3kW inverter at 120V can push 25A continuously (and likely no RCD in the path). That can melt a 10/15A cord. The inverter's own breaker (say, 30/40A) is there to protect the inverter, not the cord. The cord may "become" the fuse long before the breaker trips on an overload (it doesn't trip at 30A instantly, more like at 100-200A if it's equivalent to EU class B/C).
Update2: I'm against overregulation and panicing at every perceived threat, but I must say, I wouldn't mind an inspection taking a look for the sake of neighbors.
Update3: The PDF (https://cdn.shopify.com/s/files/1/0746/0415/1079/files/POW-L...) says that the AC input "maximum bypass overload current" is 40A. If he plugs the inverter into a wall outlet for charging/bypass, it will let his appliances pull 40A through a standard 15A socket. The main apartment panel will eventually trip, hopefully.
Where this is potentially going to cause trouble is people who don't understand how electricity works, or that different wire gauges exist, or how many watts various appliances use. The kind of person who takes a tiny lamp extension cord and plugs a power strip into it, thinking that more sockets will provide unlimited power.
The photos in this article are scary. A 2500W power strip with a bunch of crap plugged in? Exactly the kind of scenario you don't want to see. And talking about running a fricken induction cooktop off that, along with a fridge? The photo and text imply that you have near-unlimited power.
Agreed, a long run adds so much impedance that during a short circuit, the breaker won't trip instantly. It will just sit there and let the fault current cook the wires.
Various jurisdictions require a fault loop impedance test for installations (and discussed one looks "fixed"). This cannot be eyeballed from a wire diameter table, must be measured.
10awg single conductor THHN can handle 50 amps but when it's in NM-b (house wire/romex) it's 30 amps.
Extension cords can get really hot as they often have the conductor insulation, some packaging material for support, and the outer coating. It also greatly matters if it's 10ft vs 100ft due to resistance.
I've seen extension cords that were used for ACs melt carpets
It's enough to make one suspicious of the whole attitude ...
Move fast and break things has only been a VC-backed company thing.
But once you get something going, go back, apply all your learning (because you will have learned a lot), and do a little cleanup. Especially if it’s your own personal DIY project.
Cleanup does take some time so budget it in.
My first solar project initially looked like a mess of wires like OP’s, although confined to my workbench. But after I got it working, I calculated all wire gauges, put fuses and breakers everywhere, and put the right type of wires in the right type of conduits. As it had to transit a living space, I also made it look nice — you didn’t see a single bare wire anywhere — definitely no 2/0 cable running up a wall.
You could also look at it as craftsmanship.
There is this common pattern with a certain kind of HN user of not bothering to learn about something before assuming you are way smarter than any other human who has ever lived and just doing it yourself from base principles, before inevitably finding out what everyone else already knew.
If it was just diy projects it would be one thing, but entire companies are run on this principle.
You can’t even hire a competent person unless you have a bit of expertise yourself. You wouldn’t know the difference.
There is some productive Middle Way here.
If you were writing pieces of self driving code or were building a wooden chair for yourself to sit on, that change up things a bit. The most fundamental distinction isn't in whether it's hardware or software, but whether it's safe or not.
From the manual of this particular model:
https://cdn-files.myshopline.com/file/store/1675916196960/AN...
Setting 11 which default to 30A with no detail in this manual, from my experience there will be something like 2A 10A 20A 30A when you cycle the option 11 values.
Definitely on his fridge, but many newer ones are inverter drive themselves and effectively soft-start. Just 100w or whatever around the clock.
Maybe in 50 years they’ll relax my local electric code and stop requiring them to be on their own circuit. Or at least tie them with lighting so I’ll know at 8PM if the fridge has gone out for the night because the 50w of LEDs on the same branch don’t work.
I have a similar "all in one" inverter for camping, and since you seem to know what you are saying: In my setup I wired a 20A GFCI outlet to my output, and use that as my main output protection. What do you think about that?
PS: op took down their page. archive link is here: https://web.archive.org/web/20251005022124/https://sunboxlab...
It specifically protects against ground-path overcurrent (not ground line overcurrent - it is guarding against an undesigned path to ground, which is probably a person).
The 20A is not being "enforced" in any way and your outlet can receive, and pass on, any arbitrary current ... until something melts, that is.
You could achieve your goal by wiring in a fuse, or circuit breaker in that circuit and could probably nicely (and safely) package it up in a plastic junction box, etc.
Buy a customer-oriented device instead, if you can. I vaguely remember there are plenty of them on the market with built-in batteries. They should have RCD/GFCI and overcurrent protection (and thermal, and BMS included) per outlet (or per bus).
If you want to stick with your current inverter, here are some thoughts from first principles:
- ground it while using, but this might be hard at a remote camping site (maybe use a grounding rod?). If it's a similar model to the one in the article, it must be grounded.
- a GFCI/RCD rated for 30mA or less with 15-20A circuit breaker (I'd suggest type-A if in EU) that matches your wiring and outlets.
There should be ready-to-go boxes that provide RCD+OC, and maybe you're already using one.
What's the point of grounding it? So you can get shocked by touching one wire instead of two?
Longer: A Class I inverter/appliance relies on PE. A single insulation fault (live -> chassis) will put the chassis at line potential if PE isn’t connected.
If you run other Class-I loads (eg. fridges) downstream of a GFCI but don’t carry PE, a hot-to-chassis fault on the load won’t reliably trip anything until there’s a return path (often a person).
As long as the other wire is not connected to ground, chassis being connected to one doesn't pose much risk.
Grounding either wire makes whole thing worse. If you ground the chassis and it's not connected to either wire it makes no difference. Once insulation on any of the wires fails and the wire connects with the chassis it becomes the neutral and ground at the same time and the other wire will shock you through ground even if you don't touch the chassis at that time.
I'm curious if GFCI would trip if you didn't have the whole thing grounded and just touched one of the wires...
I know that in normal setup GFCI detects if too little electricity goes back through neutral relative to how much goes through hot wire. Assuming nothing is grounded, would short, small leakage current when you touch one of the wires be enough to trip GFCI?
Does GFCI work both ways? If there was more current "comming back in" on the neutral than goes out on the hot would GFCI trip as well? Are the usual solutions worthless when you have just two free floating wires with potential difference between them but with no reference to ground?
Is there a code for high voltage mobile installations? It seems that EV and mobile home makers go mostly with their own solutions derived from first principles...
The same applies to the rest of the construction industry in the US. If they're building houses out of cardboard and sticks, they should be paid enough to buy a cardboard steak. And house prices should be low, not like they are now.
This is a DIY power bank. You can buy professionally-made ones from Bluetti, Jackery, EcoFlow, and many other companies. Including with solar panels. They've been around in some form or another for decades. Modern ones use LiFePO4 batteries, which have a solid safety profile compared to older-generation lithium batteries.
Or you can buy components and build your own, hopefully more safely than the article shows.
Go hang out on r/SolarDIY or check out Will Prowse on YouTube.
Everyone speaks with such confidence that it seems like they know what they're talking about. Then they starting talking the same way about something you're more familiar with and the illusion is quickly shattered.
* Fire insurance or well, potential no-payout if your installation creates a fire.
* What about grounding? Does it also feed back over the invertor to your breaker panel
* How about power fusing... I doubt that he has individual fusing to his different rooms. So yea, electricity compliance is a mess. See fire insurance.
* Hanging cables with plugs hanging on them.. yep, very code compliant...
* A yes, 2500w rated distribution box with then multiple heavy loads on them.
This is one of those, interesting but big risk of burning down your own home, and neighbors in the process. It needs a ton of improvements for safety, what drives up the costs. Imagine everybody doing this, ...
This is pretty much a myth. Insurance pays out even if you cause a hazard, as long as it's not intentional (i.e., not insurance fraud). Talk to any insurance adjuster: undisclosed DIY is not enough to deny a claim.
What happens instead is that if you make a claim and the damage is due to stuff you didn't tell the insurer about, they will drop you right after they pay. Another possibility is that if they do any proactive inspections (e.g., drone fly-bys), they can decline to insure you or drop your policy.
A more substantial problem is that this page sort of oversells what they're pitching. 1.2 kW of solar power is a fraction of typical household usage. 2.4 kWh battery storage also isn't a whole lot. And yeah, it's cheaper than paying someone, but if your roof starts leaking, it's gonna cost you and you have no one to sue.
This is also a pretty bad outcome.
I think this could be considered intentional, because in most countries, connecting this inverter to anything (source, sink) would require certification (+tests), as it doesn't have standard electrical outlets (it varies from country to country, but in the countries I've seen, either certification is required or connecting wall/ceiling lamps is exempted from this, but verification must be done afterward).
I read about this often whenever I'm looking at guidance for one of my hobbies, and often people are dealing with it in their garage. Some jurisdictions are more okay with DIYing than others, but it's all too common that someone is taking 240V, 30A and going to an enclosure that they built to get 3+ HP/2+ kW at 240 or 480V, three phase.
The common refrain is that your insurance will deny your claim.
The response that people get when they call their insurance is "you pay us to cover you even when you do the wrong thing". Just like how your auto insurance covers you when you rear-end someone while drunk as hell, when you drape way too many lights on your crispy dead Christmas tree, or when you fall asleep and light your drapes on fire with a cigarette.
Intent is when you set out to cause an accident.
(You should probably read your actual insurance policies before considering my not-a-lawyer American-centric comments.)
I think nobody mentioned about insurance fraud. There is a difference between a accidental mistake, not knowing what your doing, and knowing that your bypassing regulation willingly.
This type of installation needs to be reported to the insurance company. Remember, coverage applies to the state of your vehicle/home/property. If you DIY your own power source, the insurance company when informed about it, may drop your coverage.
If they know about the installation, its much harder for them to deny a claim. But a hidden installation like that, is a factor in claim denying.
And we are kind of ignoring the whole "your not just putting yourself at risk but also all the other people" issue".
Yes and no; it really depends on what kind of house you have, how many people live there, and (culturally?) where you live.
I have an 1800 sqft condo in San Francisco, and a 3.6-4.0kW solar system would be what I'd end up installing if I were to do it the "normal" route with an installer and all the "red tape". Yes, that's obviously 3+ times the 1.2kW demonstrated here, but even a system like that would be useful for me to reduce my electricity costs (especially given where I live).
I know people with more modest electricity needs than I have. I also know people who have 16kW of solar on their roof and that still isn't enough to avoid pulling power from the grid sometimes. So: yes and no; it depends.
I never planned & priced out battery storage, but, sure, 2.4kWh would be pretty low for my needs, but it would still be useful.
It's just weird that the article title includes the phrase "energy independence", when the author admits that they still pull more than half their usage from the grid.
If you alter your car its electrical harnas wiring and this creates a short somewhere, resulting in your car burning down ... that is a whole difference situation then missing a mandatory inspection. One is deliberate alteration of a vehicle and one is a inspection of condition.
Most insurances have a lot of protective language (for the insurance company), that often comes down to "everything needs to be code compliant/manufacture original/...".
The bigger the damage, the bigger the chance that insurance companies will fight you. If the above mentioned installation creates a small kitchen fire that cost a few 1000 bucks, they probably are not going to fight it.
But what happens if the above mentioned installation burns down the building, kills 5 people... Do not forget that the other neighbors / building owner's insurance companies, will go after your insurance if you are identified as the cause.
The issue is that if you go to court, and a fire comes from your apartment is from a accident, or a state like this, courts are willing to side with the victim party. But if a fire is the result of your own "tampering" with devices, electrical, etc, there is a very, VERY high chance that the court will side with the insurance provider. Insurances are not blank "do whatever you want, you get coverage" type of deals.
All the commercial solar setups out there spend a lot of effort pushing power back to the grid, when all I really want is this configuration to all my outlets.
Does anyone know of a setup like this? Basically a power bank that charges primarily from solar, secondarily from the grid, and provides my normal panel with power through an inverter (or panels/inverters, I actually expect). Feeding back to the grid seems more trouble than its worth...
Like, yeah, there's some sketchy stuff with connecting those loads to this over extension cords snaked all around the house, but this setup is basically what you're asking for.
Finally, from the settings you can stop the unit(s) from sending power back on the grid so that you don't have to deal with that hurdle of changing the meter, permits, ... .
I linked an example wiring here [2]. I don't work for Victron, but I am just an happy customer :)
[1] https://www.victronenergy.com/inverter-charger-mppt/multi-rs... [2] https://www.victronenergy.com/media/pg/Multi_RS_Solar/en/app...
https://www.geninterlock.com/product/generator-interlock-kit...
No certification required. Code compliant. Idiot-proof.
You can DIY a system like that in the article, using better and/or cheaper components as needed for your use case.
If you do this, I'd highly recommend that you put a transfer switch in place that lets you connect the grid back to the breaker panel with the flip of a lever, and cut the inverter out of the loop. That way, if the inverter ever goes down for whatever reason, you can cut it out and do maintenance on it without any "why is the power still not on".
Or to put your outlets on a subpanel with the inverter controlling the feed to that subpanel. Maybe with a 2nd lockout connection to the main panel so you can do maintenance on the inverter without having no power.
The EG4 gear is really popular for this. Don't go quite as cheap on the inverter or batteries as the OP did - you want something reliable, and for doing whole-house you want rackable batteries that you can easily parallelize and that have controllers you can talk to.
You need to look for off-grid inverters. They are now really popular in Ukraine because of constant power outages.
They are also getting incredibly cheap you can buy one for less than $1k: https://signaturesolar.com/eg4-6000xp-off-grid-inverter-spli...
The state-of-the-art are inverters that can seamlessly blend off-grid and grid-tied functionality, so you can both export your energy to the grid (if you have a surplus) and smoothly fall back to the battery power if the grid is lost. And they can even control standby generators in case the battery is gets low and there's no grid power.
What blows my mind, is that you can even parallel them together to get more power if needed. They even handle the grid synchronization without any voltage spikes.
I'm familiar with this model: https://www.santansolar.com/product/eg4-18kpv-hybrid-all-in-...
I think the generic term is "islanding" (could be wrong)
The downside of my system is that it takes a non-trivial amount of time to switch to island mode, which means lots of computer things reset during the process.
So you don't get 100% uptime, but you are able to carry on when there is an outage.
The main thing I would be nervous about is the panels are claimed to be "rated for 120km/h winds". Presumably thats if they are bolted down? Just laying them down loose on the roof seems like a bad idea.
"Warning: Potential Security Risk Ahead
Firefox detected a potential security threat and did not continue to sunboxlabs.com. If you visit this site, attackers could try to steal information like your passwords, emails, or credit card details."
https://web.archive.org/web/20251005022124/https://sunboxlab...
With that said... a few hundred more dollars, and this could be a proper setup with a proper load centre, breakers, and so on. Simply replace a lot of your home's existing wiring.
Seeing as the entire project is by and mostly for renters, that's not feasible.
Otherwise said renter will quickly find themselves in violation of most lease agreements for creation of hazards on the property.
(Except when the landlord also lives there.)
Also... I lived in rented apartments for more than 15 years, and the only time a landlord entered my unit was one time when I explicitly asked her to (there was a water leak, and I was about to leave town and wouldn't be around to let the workers in to fix it). Is this a normal thing? Are landlords constantly visiting their tenants?
It mostly boils down to how nosey your landlord is. If they are constantly stopping by to inspect things or change filters more than a couple times a year it’s probably an excuse to see what you’re up to.
Really depends who manages your building. We had the most issue with the landlord who also manages the building. Like tons of inviting themselves over, very nosy and intrusive.
When we moved out and the final inspection date. We cleaned everywhere that is logical ... ground, windows, bathroom, sinks, tubs, glass, kitchen, drawers, .. you name it.
They then demanded on the move out date, that we clean above the doors, i mean, the flat part above the internal doors, outside some small toilet window that had not been cleaned in 10+ years. We even told them, why is this on us when clearly you did not do so with the previous tenant (we only lived there 1 year). No no, it became that dirty in that one year. Yeaaa, bull... May have something to do that we are "foreigners".
Plenty more crazy stuff... locations where you do not even think about like ducting. Imagine when you read this, look around, and imagine the spots where you never think about cleaning because its kind of crazy. They really looked for every excuse to deny our deposit (did not work). We had plenty of pictures from our move in date, and used them against the landlord.
Where as the building we are in now, beyond the move in date, not a single inspection or anything like that. Sure, a few times that they came to do work, like replacing the smoke detectors, or painting, but those are all 3th parties.
Learned the lesson to never rent from somebody who is the landlord and manages the property at the same time. Too much trouble.
[0] https://www.backupbatterypower.com/products/516-kwh-industri...
[1] https://www.ankersolix.com/products/535?variant=497024349310...
Show HN: My $1k self-install, off-grid solar backup build for renters - https://news.ycombinator.com/item?id=40025195 - April 2024 (229 comments)
That's thrifty; changing a panel/building a subpanel probably needs a permit, but shouldn't need utility approval. A transfer switch is an option too, but not so thrifty, and if you an automatic transfer switch, they usually work the other way (use grid if available, fail to local generation), but you could probably make it work.
[1] https://www.geninterlock.com/product/generator-interlock-kit...
Victron multiplus ii cx could be a good option.
Ideally we all could push power back to the grid & that ought not be hard, but in point of fact that can be a huge barrier.
It's not capable of generating as much power, but I love what Zoltux and many others are doing: attaching current sensors to the main breaker box, and using that as feedback to make sure the solar is never generating so much power that it pushes to the grid. Pretty mild 800w power on the Zoltux. https://zoltux.com/
The existing DJI Power 2000 added this capability with a recent software update, if you have a compatible energy meter! Can accept up to 1800 watts of solar power. I'm not sure if there's any difference between this kind of setup and a european balcony solar install? https://www.renewableenergymagazine.com/pv_solar/dji-power-2...
Also, this submission showed up two years ago. 236 points, 230 comments. https://news.ycombinator.com/item?id=40025195
Actually, the whole page appears to be 404'ing now?
When the battery is depleted, you, I suppose, just pull the plug from a battery-fed power strip, and push it into a regular socket.
I would put 3x the battery capacity, which would add about $500-600 to the cost.
Btw for the second part, you _can_ charge electric cars over just normal 15amp circuits you already have. It's just slow, so you'd only want to do it for nightly charging and it may depend on your commuting range if it'll work out or not.
The Delta Pro series is capable of running a 3 ton AC condensing unit, so if your tools are less demanding than this it should work out.
At least this particular setup uses a somewhat dignified 24-ish volt setup instead of the usual awful “12V” that is often seen in this genre of battery.
There's also nothing wrong with 12V setups (see all the RVs that are out there).
It’s “not required” in the sense that it works. Poorly. Have you contemplated how balancing between paralleled “12V” LFP packs works? LFP has a voltage vs SoC curve that is very unpleasantly flat for purposes of cell balancing without intelligence, and almost no intelligence is available in these arrangements.
> Theres nothing wrong with 12V setups (see all the RVs that are out there).
There is so much wrong with them that it’s hard to even know where to start.
Let’s suppose you have an RV-like setup that is designed to power one single 15A 120V receptacle. That’s 1800W, which is pretty small by the standards of modern inverters. It’s also 150A at 12V. Want decent efficiency? That means you want to lose less than, say, 2V on the wires, so you need to carry those 150A over a round trip resistance below 13.3mOhm. If you use the ABYC ampacity table, that’s 2AWG or larger wire. Fortunately 2AWG will carry 150A a respectable distance without excessive voltage drop.
Now, 150A is a lot of current. 150A will make massive sparks, light things on fire, and weld sizable pieces of metal even if 12V is unlikely to electrocute you. And you’re feeding that wire or bus in multiple places (because you may have multiple batteries and a beefy charger), so you remember to put giant 150A fuses or breakers at all the feed locations, right?
But wait, 12V needs below 0.08 ohms to produce 150A. Want to comfortably blow a 150A fuse? You need well below 0.08 ohms total resistance in the entire circuit, including the fault. If you have a high resistance fault (and “high” could be 70 mOhms!), you will never blow the fuse and you can produce literally kilowatts of heat. Crispy! (Your house likely has circuits bigger than 150A, but it’s at a voltage that can much more easily trip the breaker, and in civilized countries there will be some sort of RCD as well.)
Oh, and that 2AWG cable is expensive, hard to bend, and requires actual skill to terminate well. And modern systems often target powers well above 1800W.
At least in a car, the high current portion of the 12V system is made and tested in a factory. And it still makes amazing showers of sparks if anyone messes up a jumper cable. There’s a reason that car makers want to move away from it.
So I stand by my claim: 12V sucks.
Power distribution centers are not power strips and there's a reason for that
Yes, we are on the cusp of self-pluggable home solar solutions.
No, this is not the way.
Generally speaking, you're just not supposed to do permanent electrical wiring with extension cords and power strips, especially not for stuff that goes into or through walls. This has nothing to do with plastic - you have plenty of plastic in electrical boxes, outlets, PVC conduit, etc. Cable insulation is plastic too.
The electrical code doesn't want you to put extension cords in the wall mostly to make sure that the connections can't come apart, that the comparatively softer and more delicate wires aren't easily crushed or abraded, and so on.
This project definitely isn't done the way you should do it if you had a real budget dedicated to it. Is it a death trap? Meh, I've seen far worse extension-cord contraptions in US homes.
It’s more the grounding issues and lack of a properly sized circuit breaker to protect the extension cords etc.
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If this is your site, please visit Netlify’s Billing docs page or log into your Netlify account to upgrade your plan.Do they not teach "the boy who cried wolf"? It doesn't get worse than claiming this stuff will burn someone's house down around with everyone around them.
All major plumbing and appliances and power are in the trailer, the extra “rooms” have nothing much but lighting.
Not sure how it’d work in practice.
e.g. https://electrek.co/2025/09/28/yes-an-ev-really-can-power-yo...
To go off grid, you'd need a source of power to the car that wasn't your house.
I run a few of these on an off grid property and they're totally fine. I would be wary of a cheap no-name brands. I'm also be wary of running extension cords all over the place.
If you have the space (a mechanical closet?). I'd suggest getting a separate inverter and charge controller. These all-in-one units have fairly high idle inverter draw.
> small solar panels that can be easily installed on balconies and plugged directly into a standard wall outlet, allowing users to generate their own electricity.
I believe this is common in Europe. They’ve figured out some way to make it safe for the grid and line workers.
Payback period for me would be 7+ years with my electricity rates.
The idea here is totally reasonable, it just needs some of the parts more right sized etc
Not saying this is the most unsafe thing I've ever seen or heard of, but we have electrical codes for a reason... because buildings have burned down and people have died.
There a many problems with this article, but the fact that it includes a battery charger is not one of them.
But there are devices out there that do feed power over the exposed prongs of a male plug. They're called "suicide cords" for good reason.
I've wanted to build something like Roald Dahl's writing shed: https://youtu.be/AsxTR09_iWE?t=294 for a while.
I live in a climate with cold winters though, so I hate to invest in something like this and not be able to use it for a significant part of the year. I guess I could put a small pellet or wood stove in it..
Like others said not sure about that wiring though
The author doesn’t explicitly dissuade people from plugging in another multipoint/powerstrip/plugstrip into the end of the extension cable you’ve run into the other room. So I will. Don’t do that. There are plenty of low gauge, cheap extension cables out there which will degrade fast in this setup, and may cause a fire.
Also, if your landlord is okay with seeing this setup they probably don’t have insurance they’re worrying about, and are simply making sure you’re not actively destroying the property (rather than potentially destroying it with the fire hazard).
First of all, let's assume less than ideal conditions so base our calculations on 115V. 2,500 watts is going to be 21.7 amps; assuming a continuous load (which is pretty reasonable for a whole house) is going to need a breaker and wiring that's rated for 125% of that, or 27.2A.
That means the supply needs to be #10 wiring and should be fitted with a 30A breaker at the disconnect. A temporary power tap is not a suitable disconnect. And I highly doubt it's got 10 gauge wiring.
But I used the highest gauge I could find! I looked hard, but I couldn't find any with more than 16 ;p