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this post was submitted on 25 May 2024
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What the actual fuck?
Disqualified.
What's wrong with that? That's how basically any balcony solar system works.
The cables in your walls are designed for a certain maximum current before they start to heat up. This current is limited by your breaker.
Now if you introduce a plug in solar setup your current is limited by your maximum breaker capacity + whatever your solar setup can generate.
So if I'd use the specs from the article and apply it to a normal dutch home situation: 16A breaker, + 800W at 230V, which means ~3.5A = 19.5A max. which is probably still fine for short durations.
But now some genius doesn't read the fine print and hooks up 2 or 3 on the same circuit. There is no electrician that tells him that's dangerous because it's all self installed and he doesn't know any better. And all of a sudden you are up to 26.5A and you got glowing, smoking wires in your walls...
Ok sure, that makes sense. This might actually be an issue.
Your breaker will pop. Just like if you were to run a hair dryer on each outlet.
The breaker only sees the current flowing through the breaker though. Not the additional current provided by the solar panels since those don't flow through the breaker. So it will pop later then that the cables are rated for, therefore introducing an overheat and fire hazard.
Maybe for a same-circuit device that’s consuming more than the breaker can provide? I don’t know enough about this tech but would expect this can be accounted for in some way.
There are ways to somewhat fix it for circuits with a single use.
Fixing the same example: A 16A breaker for the solar feed in, a single 16A breaker for all the consuming appliances on that circuit. And another 16A breaker on the feed in for that circuit is an example that is sometimes used in the Netherlands to add a feed in to an existing circuit with a single outlet connected to it. Meant for washingmachines for instance.
This ensures that the circuit on all circumstances has a maximum current of 16A flowing over any wire by also measuring the outgoing current of both feed in circuits. But if you have multiple outlets you'd still need to stiol measure at a single place or use low enough breakers per outlet that the total stays below the 16A. Which the UK might have if I recall correctly.
Then again this is not a normal setup and requires change in the electric circuit of the home. Which most consumers won't even realize. Like I said, if everyone keeps to the fine print this thing probably has and limits the extra plug-in solar panels to 1 per circuit, it's unlikely to actually cause issues because of overdimensioning of the wires. And the safety margin built in which is likely how they have gotten approval. But ignoring or not reading that text and plugging multiple in on the same circuit can and will cause a fire hazard with heavy consumers on the same circuit.
Also, emergency service hazard. The PV won't turn off if firefighters take out the mains, which makes a house potentially inaccessible during an emergency.
Surprisingly, no. Most inverters in the EU must come with island protection. Meaning that if there is no AC from the grid it immediatly switches off the inverter or the battery, there is no stand alone operation.
There are some systems that allow it but they are rare here and require the mains side to be fed trough the inverter itsself ensuring it's never back feeding into the grid when there is no power with the same island protection, or less commonly there is a transfer switch of some kind also eliminating the issue. And either should obviously have a main kill switch on the breaker board for emergencies that also switches off the in home power with 1 action.
But most importantly, either of those options is not plug and play and will require an electrician that hopefully does know what he's doing.
Does the island protection with if you have two inverters running independently? (legally or not)
Yep, I'm not exactly sure on the technical details but it works with multiple inverters. Otherwise having a street full with solar panels on every roof would still be a hazard if the power went out at a distribution junction for said street and repairs would have to be made.
If there is no powerplant feeding some energy, all inverters should shut off. Fixed installs and plug and play variants alike. I'm actually amazed that there are parts in the world where this isn't common.
Yes, because the frequency of the grid is also a trigger for shutting off the inverter. Inverters generate a frequency which indicates a "non healthy grid" that trigger the shutoff of connected inverters.
I looked into these before and believe the inverters shut off if the mains shuts off. The DC side of the circuit would still be potentially dangerous though.
The inverters need there to be power in the mains circuit because they convert DC to AC and match the phase of the AC power they are generating to the mains supply.
First part is classic stuff right?
Should not be via a standard wall jack. As far as I know.
Depends on electrical code which depends on, most of all, your standard plugs. In Germany Schuko is deemed non-optimal, but acceptable, for up to 800W.
...no issues regarding exposed prongs, if the inverter doesn't see AC to sync to it doesn't output anything. It's not a dumb spinny magnet generator we're talking about here.
Most people don't have an outlet on their balcony, though, and weather-proofing the thing is an issue in any case so while you're at it you can just as well put in a proper Wieland outlet. 20 bucks or so, the expensive part will be the electrician not the outlet.
In the UK our everyday plug is rated for 13A - nearly 3KW. The plug on my phone charger is the same as the one on my tumble dryer and I don't know if that's a good thing or a bag thing.
Schuko is rated for 16A continuous for one hour, 3680W, I think the UK plug would actually take quite a bit more you're just being conservative. Or something odd about ring circuits I don't want to think about.
In any case practically nothing in a household actually uses 3kW. A stove, yes, but that's connected to three phases and without a plug (usually 3x20A over here -- CEE plugs can do that but they're chonkers and how often do you move your stove). Newer dryers should stay under 1kW, the standard high load appliances are kettles and hair dryers.
If it has anti islanding at least it's unlikely to be a shock hazard.
That said are there any other concerns I'm missing?
You don’t want to be sending current up into the grid while workers are repairing it during a power outage. If you just plug some shit into your bedroom outlet, that will happen. You need to disconnect your house from the mains. Whole house generators are old news, but no, your bedroom wall plug isn’t rated to power your whole house, and no, you aren’t just electrifying your own wiring if you try to do so. Whole house generators aren’t hard but they aren’t this easy. And you should be suspicious at how magically simple it sounds to just plug a dynamo into your wall to power everything. It’s the kind of thing we would love to be true because it’s so elegant but there’s a little more to it.
That's what anti islanding is.
Prevents power from going into the grid when it's down.
Way I read it is it puts surplus into the grid to keep you elec bills down.
800 watts isn't exactly going to set an outlet on fire.
I’m also against proprietary systems but is there an open alternative?