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I am kind of curious how over-current protection is achieved with these systems.
Don’t get me wrong; I think the concept is good.
But the circuit breaker is sized to protect the wiring between it and the outlets/devices it supplies. If you’re already close to the max current the breaker can supppy, then you add on a second current source (the panels inverter), you could feasibly supply+draw more current through that circuit than it was originally designed to carry.
For example: a regular 15a circuit + 5a worth of panels (600w); you could now draw 20a through wiring that’s only designed/sized for 15a, before the breaker trips. More current creates more heat, this is a potential fire hazard.
On top of that; switching the breaker off/locking it out doesn’t necessarily switch off all power being supplied to that circuit. If you’re not aware of the solar system that’s also supplying that circuit from another point (very unexpected under current norms) This could cause you to work on wiring that you expect to be unpowered when it’s actually live (you should always check with a volt meter anyway, but still, unexpected hazards).
I would imagine much of this has been thought about; but I’m curious about the solutions (or about the reasoning why it’s not considered an issue)
I don’t know how your first concern (over current for breakers) is addressed, but I trust that the Germans, of all people, have figured it out. This technology has been in wide use over there for years. I’ve heard that over there you can buy them from local big box stores and I think even supermarkets. I doubt that Germany would allow something that would be a fire risk to proliferate like that.
Regarding your second concern (power flowing back to the circuit when it’s supposed to be unpowered) I’ve read that balcony solar systems do include circuitry so they automatically stop supplying power if they detect that there is no power being supplied by the outlet.
The back feed is taken care of by the solar inverter already. If it doesn’t detect the proper waveforms from the grid it turns off.
As for the overcurrent, there are sensors (PCS) that can detect current load on a circuit. Alternatively, a dedicated circuit or oversized circuit can be set up to handle it (but would require electrical changes).
They can also test to see if the current on the circuit is grid power or another inverter (so you can’t trick it)
I imagine there are two assumptions:
Such a “balcony” system isn’t going to be 600 watts. I’ve got a pair of 100 watt panels that together would each make a fairly good awning for any of my windows. I also have a 200 watt Anker brand panel (one of those weird ones that feels like it’s made of a quarter inch thick sheet of denim) that’s the size of a beach towel. 6 of those 100 watt panels would come close to the size of queen-size bed. You’re not going to have many apartment dwellers dangling something that big out the window.
Most people most of the time don’t have circuits loaded to the very edge of the envelope. If you plugged it into a circuit that’s drawing 10 amps…it’ll still draw 10 amps. It’s just that ~8.2 of them are coming through the breaker, the other ~1.8 are being provided by the solar panel.
It does still sketch me out a little because it breaks certain fundamental design rules of the power grid. Power should come from female sockets not male plugs, and it should come from before a breaker, not after.
This isn’t how I’m doing my personal solar power.
I picked 600w for nice round amperage numbers in the above math; even just a few hundred watts presents the same issues though. You could fit a decent size set on the balcony, covering the outside of the balcony railing.
I wouldn’t be so sure on the second point. I live in a 3bed apartment with 2 main outlet circuits. 1 supplying the livingroom and half of one bedroom. Another supplying the other two bedrooms + the other half of the 3rd bedroom.
Between the main entertainment/lighting electronics in the livingroom, the portable ac in the adjoining bedroom, the watercooler/heater, and recently a set of ebike battery chargers; that circuits base load sits around 6.5a during a charge cycle, with peaks right around 15a when the ac runs+the water cooler, occasionally peaking right up to 16.5a. I’ve tripped the breaker a few times running the vacuum at the wrong time ontop of those.
The other bedrooom circuit is similarly loaded with a couple computers, device chargers, and another ac (cooling is crap in this place plus our unit faces the sun all day); though not quite as heavily as the other circuit.
The living room circuit is where a solar system would be installed (it’s where the outdoor outlet is connected) and the main appeal of a system like that is not having to modify wiring since we’re not allowed to touch that as tennants (the corporate landlord is rather unlikely to allow modifications even from a licensed electrician either).
Supposedly the solar inverter would shut off during a mains power outage, but is it fast enough to prevent shock if the plug was disconnect and touched?
IDK, interesting systems, just curious about them. I’ll have to look closer when they’re actually available.
Unfortunately this is awful terrible engineering ethics and does not fly in the real world. “Most” implies that there WILL be a nonzero number of edge cases where someone does have circuits loaded to within an inch of their lives, and a plug-in solar system will lead to a house fire.
I would agree. Hence why I said “This isn’t how I’m doing my personal solar power.”
Apparently American units are coming with an outlet you install in place of a standard outlet which does monitor the combined power, so the building will have to be modified slightly. Still…any more than a couple hundred watts, if you can, have a proper system installed.
This doesn’t sound right: measuring at one outlet doesn’t grantee you’re measuring the full circuit load unless you can be absolutely sure it’s the very first outlet in a branch circuit specifically. A ring circuit throws that idea out entirely. To measure reliably, you’d have to measure at the breaker itself as well as the solar inverter.
Maybe a replacement breaker, that measures and comunicates with the imverter?
You run into compatibility issues with the different electrical panel manufacturers though…
Idk, I’ll have to get my hands on one of these kits when available and look closer.
About the second point: it appears they will need the same grid intertie circuitry that inverters need …
“…and include equipment that prevents power from flowing back to the grid during an outage”
I wonder how fast that shut off is. Will it prevent a shock if you unplug and touch the male plug?
I’ve read that balcony solar systems do include circuitry so they automatically stop supplying power if they detect that there is no power being supplied by the outlet.
Yeah, the idea is nice, but it smells an awful lot of wall socket generators and suicide cords
Not sure what’s up with the downvotes, that’s a legitimate concern any time you’ve got a male plug supplying power… It literally IS a solar wallsocket generator with what’s essentially a suicide cord permanently attached.
I’m sure they’ve put some protection in place; but still.
Oh, it’s because I skipped out on the preemptive disavowal.
See, the vast majority of lemmy is functionally illiterate, so if you wanna object to, eg., solar panels, you have to start your comment with something like “Well, I agree that global warming is a huge problem, and solar is a way to fight it, and I support more solar […] but,…” or else the feral hogs on the thread will just see you saying “solar bad” and assume you’re a flat earther.