It is more than just the concern around back-feeding the grid. These simple balcony setups connect to your home grid via a single outlet. Most US outlets/circuits are 15 AMP or roughly 1500 watts max capacity. These single circuits can only carry that much current total at any one time so if you have it loaded up with incoming power AND use anything else on the circuit at the same time … no bueno. To make this setup work best/safely you would ideally want a dedicated circuit for it which is basically non-existent today.
The safety issues really do need to be addressed because the folks most likely to use these systems are apartment dwellers and I don’t think anyone wants to increase fire risk in these scenarios.
His point was that if you’ve got 1200w incoming from the panel then you only have 300w of overhead on that circuit before the circuit breaker blows.
Sure, it’s within the limit on its own, but without a dedicated circuit for it you’ll be blowing a fuse pretty frequently when trying to use nearby plugs and lights.
Idk man. It’s probably over my head but I still don’t think the wires themselves could take it. In my thought process you’ve got more electricity flowing around on the circuit and even if it gets used before getting to the breaker things are going to be heating up pretty quick.
To me it sounds like trying to hook up a power plant to a data center via an indoor extension cord. It’s gonna melt.
I think the warning you might be thinking of is that a breaker can fail to pop if an inverter/generator is on the same circuit as a high wattage device. Since some energy would go directly from generation to device, the breaker will only see the “net” energy consumption. So if the generator puts out 1500W and the device decides to draw 3000W, a 15A breaker only sees 1500, and won’t trip even though the device is pulling way too much. If the breaker was sized for the wiring, then the wiring to that outlet could catch fire due to the breaker not tripping. That’s the main reason I know of why a generator or inverter should be on a dedicated circuit, to force the energy out one breaker and in another, so that the breaker can see an accurate measure of energy and trip when necessary.
even if it gets used before getting to the breaker
It would be both added and consumed after the breaker. Like if you had a 10A solar system connected to a dual outlet, and a 10A space heater on the other outlet, there would only be 10A flowing through the outlet, and nowhere else in the system
Yes, I was conceding that point. I was then worried about the actual romex in the walls entirely contained after the breaker. Are you able to pump as much power as you want at 15A on a 15A rated wire? There’s got to be some limit, right?
Ok, cool. So if the romex is rated at 15A then I’m going to assume that’s the rated safety limit before things start to get sketchy.
This panel is going to provide 1200w at (I’m assuming) 120v which is 10A.
At that point I plug in something that pulls 1500w (120v for 12.5A total) like a hairdryer.
You’re saying the load on the circuit breaker will be 1500w-1200w for a total of 300w (2.5A), correct? The load on the romex in the walls after the breaker will still be 1500w (12.5A), correct?
What happens if I then plug in a space heater on that same circuit which consumes 1500w (12.5A). The breaker load should then be 15A (the net 2.5A + 12.5A) as it’s rated for and shouldn’t trip, but the load on the romex after the breaker would be 25A (12.5A + 12.5A), 167% its rated capacity.
Am I misunderstanding something? I’m honestly not trying to argue. I’m trying to understand.
I think the risk is more that someone has a 15A-rated outlet on a 15A circuit breaker, plugs a solar panel into one socket and then a power strip with 30A of space heaters into the other socket. Breaker doesn’t trip because the main panel is only providing 15A, but the outlet lights on fire.
Not sure why that isn’t a problem in places these are more common.
This is not it. Not only is there a microinverter and a breaker there to address that issue, but my understanding as a layman is the load in the circuit is down to how much you’re drawing (i.e. if you’re generating 1200 behind the microinverter and pulling 1500 you’re pulling 1500 through the circuit, not 2700).
The bigger fire hazard here is the battery many of these come with for storage, honestly.
That’s not to say there isn’t a bit of a risk. You need to be careful if you need to do something in the installation that you disable both the grid breaker and the microinverter. Otherwise it’s entirely possible for the grid safety to blow and the inverter to keep pumping power into your house. But as the previous poster says, there’s a reason these are legal to install in apartments all over Europe, and it’s not just European grids being set for higher amps. FWIW, most of these kits come with 800W max out. My understanding is they’re perfectly fine to use as a cost mitigation and they’ll keep your fridge going in a blackout but no, they won’t be constantly tripping your fuse.
There are a lot of circuits in the US that power multiple duplex outlets around a room. You could plug in a solar panel into one outlet and a load into another and they would be connected by a length of Romex in the walls.
Generally that’s fine and I agree, but one edge case that people overlook that I think is worth mentioning (and maybe what gp heard about and is trying to articulate) is that having an inverter or generator on the same circuit as a big energy consumer means that the breaker wouldn’t see the total energy being used by the consumer, and so it might not trip even if the consumer pulls too much wattage. That’s the main reason I know of why power sources should be on their own breaker - so it doesn’t hide power from the breaker but forces it to go out the generator circuit breaker and back in the consumer breaker so it can be protected properly.
It is more than just the concern around back-feeding the grid. These simple balcony setups connect to your home grid via a single outlet. Most US outlets/circuits are 15 AMP or roughly 1500 watts max capacity. These single circuits can only carry that much current total at any one time so if you have it loaded up with incoming power AND use anything else on the circuit at the same time … no bueno. To make this setup work best/safely you would ideally want a dedicated circuit for it which is basically non-existent today.
The safety issues really do need to be addressed because the folks most likely to use these systems are apartment dwellers and I don’t think anyone wants to increase fire risk in these scenarios.
That’s why they’re limited to 1200 watts.
His point was that if you’ve got 1200w incoming from the panel then you only have 300w of overhead on that circuit before the circuit breaker blows.
Sure, it’s within the limit on its own, but without a dedicated circuit for it you’ll be blowing a fuse pretty frequently when trying to use nearby plugs and lights.
As I said, that’s not how that works. You can have 10A incoming and 10A outgoing and the circuit load is still 10A.
Idk man. It’s probably over my head but I still don’t think the wires themselves could take it. In my thought process you’ve got more electricity flowing around on the circuit and even if it gets used before getting to the breaker things are going to be heating up pretty quick.
To me it sounds like trying to hook up a power plant to a data center via an indoor extension cord. It’s gonna melt.
I think the warning you might be thinking of is that a breaker can fail to pop if an inverter/generator is on the same circuit as a high wattage device. Since some energy would go directly from generation to device, the breaker will only see the “net” energy consumption. So if the generator puts out 1500W and the device decides to draw 3000W, a 15A breaker only sees 1500, and won’t trip even though the device is pulling way too much. If the breaker was sized for the wiring, then the wiring to that outlet could catch fire due to the breaker not tripping. That’s the main reason I know of why a generator or inverter should be on a dedicated circuit, to force the energy out one breaker and in another, so that the breaker can see an accurate measure of energy and trip when necessary.
I do know, man.
It would be both added and consumed after the breaker. Like if you had a 10A solar system connected to a dual outlet, and a 10A space heater on the other outlet, there would only be 10A flowing through the outlet, and nowhere else in the system
Yes, I was conceding that point. I was then worried about the actual romex in the walls entirely contained after the breaker. Are you able to pump as much power as you want at 15A on a 15A rated wire? There’s got to be some limit, right?
No. You can only pump 15A. But you’ll never have more than that.
Ok, cool. So if the romex is rated at 15A then I’m going to assume that’s the rated safety limit before things start to get sketchy.
This panel is going to provide 1200w at (I’m assuming) 120v which is 10A.
At that point I plug in something that pulls 1500w (120v for 12.5A total) like a hairdryer.
You’re saying the load on the circuit breaker will be 1500w-1200w for a total of 300w (2.5A), correct? The load on the romex in the walls after the breaker will still be 1500w (12.5A), correct?
What happens if I then plug in a space heater on that same circuit which consumes 1500w (12.5A). The breaker load should then be 15A (the net 2.5A + 12.5A) as it’s rated for and shouldn’t trip, but the load on the romex after the breaker would be 25A (12.5A + 12.5A), 167% its rated capacity.
Am I misunderstanding something? I’m honestly not trying to argue. I’m trying to understand.
1200 incoming + 1 hairdryer at the same time equals overloaded circuit though.
That’s now how that works. You got 1200 coming in and 1200 going out, so the solar would just power the dryer directly.
I think the risk is more that someone has a 15A-rated outlet on a 15A circuit breaker, plugs a solar panel into one socket and then a power strip with 30A of space heaters into the other socket. Breaker doesn’t trip because the main panel is only providing 15A, but the outlet lights on fire.
Not sure why that isn’t a problem in places these are more common.
(this is the same reason that big solar systems require an oversized busbar on your main panel)
Ah, that is a good point. I wonder how they’re mitigating that.
breaker masking
This is not it. Not only is there a microinverter and a breaker there to address that issue, but my understanding as a layman is the load in the circuit is down to how much you’re drawing (i.e. if you’re generating 1200 behind the microinverter and pulling 1500 you’re pulling 1500 through the circuit, not 2700).
The bigger fire hazard here is the battery many of these come with for storage, honestly.
That’s not to say there isn’t a bit of a risk. You need to be careful if you need to do something in the installation that you disable both the grid breaker and the microinverter. Otherwise it’s entirely possible for the grid safety to blow and the inverter to keep pumping power into your house. But as the previous poster says, there’s a reason these are legal to install in apartments all over Europe, and it’s not just European grids being set for higher amps. FWIW, most of these kits come with 800W max out. My understanding is they’re perfectly fine to use as a cost mitigation and they’ll keep your fridge going in a blackout but no, they won’t be constantly tripping your fuse.
If you use anything else on the circuit the power from the solar will just go directly into that device and bypass the wall wiring entirely.
There are a lot of circuits in the US that power multiple duplex outlets around a room. You could plug in a solar panel into one outlet and a load into another and they would be connected by a length of Romex in the walls.
Generally that’s fine and I agree, but one edge case that people overlook that I think is worth mentioning (and maybe what gp heard about and is trying to articulate) is that having an inverter or generator on the same circuit as a big energy consumer means that the breaker wouldn’t see the total energy being used by the consumer, and so it might not trip even if the consumer pulls too much wattage. That’s the main reason I know of why power sources should be on their own breaker - so it doesn’t hide power from the breaker but forces it to go out the generator circuit breaker and back in the consumer breaker so it can be protected properly.
This is why balkonkraftwerk is limited to 800 W feed-in.