(I note that in the alternate universe where Ed Miliband became PM because he didn't eat a bacon sandwich, we could have had this a decade ago. It is embarrassing to be beaten on environmentalist regulatory efficiency by Germany)
British industry and standards bodies think this is an unsafe plan.
Of course they would because it's work being taken away from them but it would be allowing people to plug generators into ring finals with unidirectional breakers. It's not even guaranteed that the circuit is protected by anything newer than fuse wire or an MCB. No guaranteed earth leakage detection. No guaranteed surge protection. Relying on the cheapest inverters to sync frequency accurately. And
I have more faith in German standards and work ethic than our own.
I am not very well versed on this topic but I believe the balcony solar products market one of their safety features as "anti-islanding protection". Personally I wonder what happens if multiple balcony solar systems are connected... can each still tell when the grid is down since the other power source is active?
Unless there's so much generating capacity available that they can power the entire connected grid, no.
Consider 100 homes on a power line network and the breaker trips. They probably draw 50kW on average, more if it's hot or cold and AC is on. Unless there's enough power generation available to power that entire load, voltage will drop and any halfway reasonable hardware should give up.
my understanding is that micro-inverters send an "up and running" signal encoded over the DC wiring to the main inverter, and that this is used to detect micro-inverter failure. that is an entirely different problem than the one in the GP comment, i think.
Again, entirely different to the point being raised.
You have 4 neighbors, all with grid-tied inverters, all of which will do rapid shutdown if the grid goes down.
The grid does go down ... but are there circumstances under which the presence of neighboring inverters will "hide" the grid being down from each inverter, and so they will keep delivering power back to the grid ?
The situation in germany is essentially the same, but that's why net supply by these is limited to 800 W. I don't think anything changes w.r.t. earth leakage, why would the presence of the solar supply change anything from the RCD and fault point of views, respectively?
Not expert but one difference is that in Germany the standard wiring is radial circuits with 16A MCBs while in the UK it's ring wiring with 32A MCBs.
So in the UK we have 2.5mm^2 wires in a ring on a 32A MCBs... Of course a 2.5mm^2 wire is rated ~20A so any issues with the ring (sockets still work since connected from the other branch) can burn the wire before the MCB trips...
The "standard" wiring is 1.5mm² on 16A MCBs which are rated to trip at 1.13-1.45x nominal current (so 18-23 A). So this is already mildly improper because you can pull elevated currents continuously and dramatically shorten the life of the insulation.
We would call it "a serious code violation." It's prohibited in the NEC and always has been, it's objectively less safe.
From what I understand the UK allowed it because of a severe postwar copper shortage and it persists to this day because it's allowed and a bit cheaper.
> From what I understand the UK allowed it because ...
I'd say "severe post-WWII money shortage". After wartime expansion, the global copper industry could physically meet peacetime demands. But the UK was very close to national bankruptcy. And the Luftwaffe had turned an awful lot of their prewar housing into rubble. So - any cost that could be cut, was.
If your generator is plugged into their own circuit, it wouldn't change much.
If you plug it into an overloaded ring final (which is not uncommon in the UK - half our house's sockets are on a single ring), you have to rely on the generator being able to detect faults to protect that circuit.
You could also overload that circuit's wiring. If you have a a 16A Ecoflow, plug it into a 32A ring, you could draw 48A before tripping the grid circuit breaker, potentially causing significant heat in the wires. Dinky 3A generators won't do that but I don't think they're the limit our government are talking about.
Yes they are. Current alternates direction, but power usually only flows in one direction, from the input terminal (from the bus bar) to the output terminal (that the circuit is wired into).
If the circuit will be supplying power too (e.g. battery storage, an EV and EVSE that supports powering the house from the EV, etc) then you need a bidirectional RCBO.
People with no differential fault protection need not worry about any of this, they'll just be killed when it goes badly wrong.
EDIT: To say nothing of people with unidirectional electricity meters; plugging these into those setups will get them prosecuted for electricity theft. All SMETS 2 smart meters are bidirectional; you'd best check your meter if it isn't one of those.
Between the phasing out of analog meters (the latter half of the last century) and the introduction of smart meters (2010), a lot of electronic prepayment meters produced for the UK market would set a tamper flag if they detected power flowing backwards through them, as a proxy indication of an attempt at electricity theft. These meters will refuse top-ups in this condition, requiring you to contact your energy supplier to sort it out, leaving you without power until you do and then exposing you to scrutiny when they arrive.
Pre-smart non-prepayment electronic meters (for those with old meters, still submitting manual readings, and paying by direct debit) will be fine. Most of these meters, and all smart meters, are inherently bidirectional, because they maintain 4 counts (energy imported and energy exported, in kWh and kVARh) and your energy provider will do all the necessary math to figure out what to actually bill you for (residential customers are not billed for kVARh usage).
The UK government in 2011 announced plans to have 50 million smart meters installed by the end of 2020. In typical overpromise underdeliver government fashion, they didn't even achieve half of that; by then, only 23.6 million had been installed, and of those, 4.5 million had stopped working because they were initially (and stupidly) designed to be tied to a specific energy provider and the customer had changed provider. This even affected me.
Nevertheless they'd still accurately track energy consumption and export even if they'd lost their reporting capability, so you have nothing to fear here. This situation has been rectified at the redesign stage with provider-independent SMETS 2 meters, and all SMETS 1 meters still in service have been hotpatched to bring them into line (restoring their smart functionality regardless of provider).
Even today (well, as of last September), this number is only 40 million, with only 36.7 million of them actually working as designed (reporting readings automatically).
This leaves up to 16 million properties with a meter that may stop working and expose you to a theft investigation when you obtain generation capacity that even momentarily exceeds your usage (for example if you have a dual RCD board and one of the RCDs trips, taking out half of the circuits in your home, but not the one the inverter is plugged into).
Realistically the true figure is probably around a quarter of that; prepayment meters were very popular among the renting population of the time, and those who wanted to track their energy usage carefully and only pay for it with cash as and when needed, and sometimes people had these meters forced upon them by suppliers after the customer had demonstrated poor payment history, but they were far from the norm.
Average home owner buying plug-in solar at a supermarket isn't going to know or care about any of this. They'll just plug it in, and it will work, until one day maybe it doesn't and their supplier opens a theft investigation.
I feel like the meter suddenly "breaking" is the substantially larger inconvenience. Presumably the supplier will raise an eyebrow at the flag, glance over the place, see the solar setup and get on with life. At least one would hope. They must have seen this a time or two by now after all.
The kind of meters we used to install 50 years ago would turn backwards if electricity flowed backwards.
So if you spent a week with the meter connected normally, then you swapped the input and output cables around for a week, the meter would be back at zero. Free electricity!
They used anti-tamper seals to make it more detectable, but there are ways around that sort of thing.
That’s an RCD, not a breaker. Guess the English still insist on using nonstandard terminology, like “lift”, “bonnet”, “torch”, and, apparently, “breaker”. Oh well.
This is not an RCD, it's an RCBO. It combines the functions of an MCB (Miniature Circuit Breaker) and an RCD (Residual Current Device) in one device, as specified by BS EN 61009 (Residual Current Operated Circuit Breakers with Integral Overcurrent Protection).
It would be really interesting to know what's so special about these UK units that they can be "damaged" by being fed from the "wrong" side (as per some other article), considering that the only place where these behave like that is an island north of France.
These are not just circuit breakers/MCBs, they are RCBOs which combine an MCB + RCD in a single unit. RCDs traditionally only measure - and protect - current flow is one direction, so if you are using them for solar you need a bi-directional unit for full protection. The device will not be damaged, it just won't protect you.
However in the case of a UK home, where you may have a single ring circuit connecting all the sockets on the whole floor, what's in the breaker panel isn't going to protect you with plug-in solar anyway. Better hope what you are plugging in meets UK standards and isn't just some Chinese rubbish that claims it does.
Outside the UK, neither RCDs nor RCBOs (type A/AC) are generally distinguished by bidirectionality (all search results about this being .co.uk), since the RCD part of these devices is just a current transformer driving a trip solenoid; there is nothing in it that's powered by the line, nor something which could sense net power flow direction. The situation is different for AFDDs or type B RCDs, since those have active, powered electronics in them which need to be fed from the line side.
After some research the main reason seems to be two-fold:
Answer #1: Many UK RCDs/RCBOs are actually single-pole devices and don't disconnect the neutral. In the simplest case, this means pressing the test button might burn out the test resistor when backfed. I don't imagine this to be a problem in practice, since grid-tie inverters shut down very quickly if the grid disappears under them, especially plug-in inverters. RCDs/RCBOs elsewhere are virtually always disconnecting the neutral, so don't care about this.
Answer #2: It looks like some/many one-module wide UK RCBOs _do have_ electronics in them, even if type A, because they're actively driving the trip solenoid of the MCB part, and if you sketch this out and do it in a very cheap way it's easy to see how you could burn that out if backfed (i.e. powering the trip solenoid during a fault is assumed to disconnect in a very short amount of time, but if backfed for longer than the disconnect time that might be enough to toast the solenoid or the driver).
Notably neither of these has anything to do with the direction of power flow.
> Answer #1: Many UK RCDs/RCBOs are actually single-pole devices and don't disconnect the neutral.
This is not correct; all type AC and type A RCDs used in British consumer units disconnect the neutral as well. Some RCBOs do not disconnect the neutral and this is a problem in some circumstances. The datasheet I linked for Wylex NHXS1 RCBOs explains that these ones do disconnect the neutral.
> Answer #2: It looks like some/many one-module wide UK RCBOs _do have_ electronics in them [...] but if backfed for longer than the disconnect time that might be enough to toast the solenoid or the driver
This is correct. For an example of this construction in an RCBO, see [1]. This illustrates that if the supply is connected to the "To Load" part of the schematic (toward the end of the video), as it would be if the supply is a solar PV inverter with battery storage, then it can continue powering the electronics and be shunted out by the thyristor after it has supposed to have tripped, very quickly burning itself out.
Bidirectional RCBOs are not designed in this manner. They have more complicated circuitry that makes them more expensive to manufacture, but are absolutely required in situations like this if you don't want your protective devices to burn and/or explode when they operate.
> Notably neither of these has anything to do with the direction of power flow.
Yes it does, because if the power is flowing backwards to how they designed it, that is backfeeding it, keeping its circuitry powered after it should have been disconnected.
NEC doesn't specify GFCI breakers, it merely requires receptacles in certain areas have GFCI protection, and accepts GFCI breakers as one way to provide that.
The conventional practice in the US is still to use GFCI receptacles rather than breakers.
Because NEC 210.12 requires all devices to be protected. Which means if you have a switch or splice before a plug the only way to protect those is with an AFCI breaker. The only exception is a continuous run from the breaker to an outlet in metal conduit or MC cable. Given how much is romex this effectively forces AFCI branch breakers.
I find that receptacles tend to break prematurely if they are wet locations, even if 'protected' with a weatherproof box etc. You also need to know where the receptacle is and make sure it is accessible instead of behind a piece of furniture etc. Then some electricians misunderstand and put receptacles throughout the run (much more expensive than one breaker which is about 2x a receptacle), and in edge cases you need to know the order in which to reset them to get things working again. I much prefer to just have everything in the panel.
Always important to note that "code" does not mean "must meet this standard". Many existing installations will not meet current code and there are varying levels of code (at least in the UK) that mean anything from an electrician can ignore minor faults through to network-notifiable issues.
But that's rather the point here that consumers are the ones who are going to be plugging in these devices, with no appreciation for their circuits and safety devices. The only code that matters is the last version of it adhered to when their home was last wired. In extremes, that can be 40 years or more.
sure, but everything new must meet current code. nobody upgrads when code changes anywhere. Codes from 40 years ago were not bad, though things are always improving.
I find it interesting because often the best way to achieve a safe building code is to learn by allowing with basic guard rails and iterating as things happen. This isn’t ideal for the rare individual impacted by the “things happening,” but collectively we refine and iterate. Our current standards weren’t arrived at by navel gazing - we got the codes we have by experience. It’s hard to realize that from the present that you can’t reasonably learn without doing and by constraining without learning prevents growth and learning.
"Things happen" is a interesting way to say "houses burn down and kill everyone inside". And I don't believe that electrical standards were developed with the idea that houses could both consume and generate electricity.
Not to mention that most houses aren't up to current electrical standards, much less fire codes.
Are there lessons on safety that need to be learned here? We already know what the happy path looks like, and we've plenty of lessons on what the unhappy path will look like.
It isn't as if electric charge coming from balcony solar panels is some new magical-seeming type of electricity.
Safety is statistical and depends on human behavior. Unexpected behaviors might appear. For example some places require a power outlet on kitchen islands because with out, people will use cords to the wall which creates tripping hazards.
Also, why do wires have to be fixed to joists every 300 mm? It's not about the electrons.
In the US, Utah has allowed balcony solar since May 2025 and Virginia is expected to allow it starting in January 2027 (awaiting the governor's signature).
He also removed the effective ban on onshore wind construction that was introduced a month after he lost the election, restarting after a decade of lost opportunity.
This Trump-level idiocy that is just never mentioned, even as people blame the gas burned in england on windy days as a cost of wind curtailment, when the curtailment is more a like a third of the cost. Burning gas to power people who chose not to build turbines is the other 2/3rds.
In the alternate world that is tens of billions of gas costs avoided to date and tens of billions more in future.
I always blew my mind that people don't mention this more. The UK is blessed with some of the most plentiful and reliable wind resources on earth, and mediocre solar resources at best.
Banning onshore wind turbines was just insanity. Despite the insanity, the UK has made great steps with offshore wind, but offshore wind is expensive and has all sorts of accompanying headaches. Onshore is super cheap and quick to build per unit power by comparison.
Onshore wind turbines are going to be much more important to the future of UK energy independence than balcony solar.
That seems rather dumb. I wonder why they blocked the Ming Yang thing in Scotland? The UK seems to make quite a lot of dumb energy decisions like blocking UK North Sea gas and then buying North Sea gas from Norway.
There's just not much gas left in the UK North Sea.
> Industry body Offshore Energy UK (OEUK) claims that more oil and gas could be extracted by 2050. However, the ‘High Case’ scenario for future production in a report for OEUK would still mean that 92% of production has already occurred.
...
> Compared to the maximum oil production that occurred in 1999, UK output in 2025 was 77% (over three-quarters) lower.
China bad. In case of supply chain attack perhaps. It doesn't matter anyway because the Chinese have basically won by moving forward while others were bikeshedding, focusing on diesel emissions cheat devices, closing down nuclear power stations, burning Russian gas on a windy day, not having a proper grid capacity to move electrons South, delivering brexit and so on.
Yes it is rather 'dumb'. Apparently the policy is to reset relations with the EU so perhaps selling out to Siemens is deemed preferable, or perhaps they got the usual friendly phone call from Washington D.C, it is difficult to follow. And that's the point: Where is the plan? Where is strategic thinking?
> I note that in the alternate universe where Ed Miliband became PM because he didn't eat a bacon sandwich, we could have had this a decade ago
I read what is happening in exactly the opposite way. To me it shows that Milliand and the government at large do very little with no strategic thinking and no plan (same as the guys before in fairness but this government was supposed to be soo different...) and, in this case, is only reacting in a panic after almost 2 years in office to the pressure of "doing something" because of the Iran war, while also being told (slight mitigating circumstances for Milliband) that it mustn't cost anything. I always picture scenes from The Thick of It/ In the Loop when I imagine how they come up with 'ideas'.
I find it fascinating how this comment comes up with a whole theory of what happened, along with implications about how the government, and Ed Miliband in particular, think and act, and it’s based entirely on just dreaming up what the facts are, when in reality the facts can be looked up trivially, including the fact that this was in the manifesto, or other facts that are known by anyone who has any knowledge about how govt (especially the UK govt that is designed to be conservative and slow moving) works.
Like you just invented a story and made massive implications based on the invented story, with absolutely no hesitation. And you’re probably in at least the 50th percentile of intelligence.
Government press release with a long list of pull quotes: https://www.gov.uk/government/news/government-to-make-plug-i...
(I note that in the alternate universe where Ed Miliband became PM because he didn't eat a bacon sandwich, we could have had this a decade ago. It is embarrassing to be beaten on environmentalist regulatory efficiency by Germany)