I mean, it makes sense to me that consumers can’t be pumping energy into the grid with no way to cut it off, but I’m not a lineman or some sort of civil engineer or whatever.
But if I were a lawmaker, I’d be on the phone with the Germans, who have 1.2M of these connected, and figuring out if and how they’re doing it safely. But lawmakers seem to be somehow incapable of reaching out to people who know fuck all about anything.
What happens when someone makes an unsafe backfeed into a downed grid and then other nearby inverters detect the current and bring themselves back online? Is there a way to detect if the load is being delivered from the utility vs from incorrectly configured solar or generator installations?
Some others are arguing back and forth about this elsewhere in the thread and I see the reasoning: unpermitted systems could accidentally energize isolated portions of the grid during downtime, which might trick properly installed systems to also come back online, and you have a runaway effect where there is enough current present to allow addition safety systems to be fooled.
There isn’t any data transmission over the wires; there either is current, or there isn’t. Arguing over permitting is moot - either safety systems can handle this scenario already, or they can’t.
All paperwork does is slow the relief of dependence on the utility, which hurts their profits.
The same thing that currently happens when somebody does that with a gas generator? Linepersons get zapped… people get sued… etc…
There isn’t any data transmission over the wires…
That’s very wrong. Not only can you extend Ethernet in your own home using your power outlets, the power companies have been reading meters this way for decades.
How do you know? In a typical solar system, you have to have a permit, which requires an inspector to come out and ensure everything is configured correctly and safely. These don’t require any permits, which is great for making them more affordable and accessible, but there’s also no one coming around to make sure that anyone is doing it safely.
Easy check, grab a voltmeter and do it yourself.
Pull the plug, set voltmeter to AC, and read the voltage across the prongs. If you get anything over the usual float voltage you get from just holding the probes ungrounded, then you have a problem.
The PRODUCT is designed to stop feeding OUT the plug if it doesn’t detect CURRENT from the socket. AC is alternating current so it pulses on and off so the solar system is doing the same. It’s turning on and off quickly and seeing if it gets power back and if it detects no power incoming it shuts off the power from the solar. It’s quite simple and ingenious.
“The utility” has never had a way to prevent you from doing something dangerous with your wiring or with the electricity they send you. The best we’ve managed has been to encourage appliance manufacturers to design their products with safety in mind, through the UL program (which is voluntary). This is why the writer talked to the “vice president of engineering at UL Solutions.”
Inverters in the US are all listed to UL1741-SB which dictates that they shall cease to energize their AC outputs if they sense an absence of grid voltage.
Now, one thing people are ignoring is that UL1741-SB allows for islanding protection, and the disablement of it. If an inverter has its settings changed such that islanding protection is OFF, then the inverter will keep sending power to the “grid” because it thinks it’s operating on a microgrid that was previously disconnected from the larger grid via a Microgrid Interconnection Device (MID).
The settings these inverters have are user-settable, which means they need to be checked by a qualified person, either a contractor, engineer, or inspector. These settings must also often be checked by the utility you’re interconnecting to before they allow you to energize, so usually all of these parties have eyes on the inverters’ settings and can stop work before energization until things are corrected.
Ultimately I agree with you. If we don’t want to have to need inspections for every solar installation, especially residential ones and especially where plug-and-play solar modules are used, then inverters need to have their settings pre-configured for the grid code in the factory that then cannot be changed by the user or operator in the field. That would be a way to shoe-in this kind of installation.
Hard setting grid codes into inverters prior to shipping to site might be overly conservative though, especially as utilities change their grid codes over time. You need to have a way to update those settings, which could be using a wireless portal hosted by the inverter OEM with credentials made only available to the OEM. Problem with this is that then you shift the burden of configuration to the manufacturer which already has a ton of other UL standards as well as rules and regulations to follow.
I agree with everything you said except shoe-in, because it’s shoo-in.
But you articulated (better than I was going to) the number one issue. Power companies need insurance and their insurance will be affected if ordinance permits basically unchecked generators being plugged into the grid. And before anyone says it, you are not allowed to just plug your generator into your house. Does it happen? Yeah, people have been dumb since day one.
But there are transfer switches that allow for this operation in a safe manner, and the easiest way to deal with this is to have them installed by default in new construction, and to provide incentive for upgrading your panel to include one.
Inverters in the US are all listed to UL1741-SB which dictates that they shall cease to energize their AC outputs if they sense an absence of grid voltage.
No, they are absolutely not. I don’t know where people are getting this idea. Many inverters aren’t even UL listed. There is absolutely no requirement for them to be. If that were the case, off-grid inverters wouldn’t even be allowed to exist. I own several that do not have this capability and are not UL listed.
they need to be checked by a qualified person
Not in the case of Utah’s new “balcony solar” laws. That’s the problem.
which could be using a wireless portal hosted by the inverter OEM with credentials made only available to the OEM
Oh goodie, I’ve always wanted DRM for my inverter.
What do y’all think?
I think it should just require a permit, like every other solar installation. Unless we can provide data to show that it’s not a problem in existing areas where this is common, and we research and follow their regulations.
Yes but many inspectors and insurance companies won’t want you to install electrical equipment on “real property” or buildings if it isn’t UL as that falls into the scope of AHJs and insurance providers. If there’s something that has the potential to start a fire, you need to have safety certifications so operating the system not only reduces the risk of fire, but also selling the house in the future to a new owner doesn’t come with excess burden on behalf of the next insurer.
If your solar system is off-grid AND off-building, I see no reason that you need to have a UL listed system.
This is of course dependent on local AHJs and utilities, but UL 1741 covers both standalone (off-grid) and grid-interactive (on-grid) inverters. If you’re choosing an inverter manufacturer that makes non-UL listed off-grid inverters, I would probably be suspect of their products’ quality as it’s easier to gain UL listing regardless of how the inverter is used: off-grid or grid-interactive.
That’s the problem.
That is a problem. Off-grid inverters that aren’t certified to UL 1741-SB aren’t required to have anti-islanding protection that cuts the inverters off if there’s an absence of grid voltage. If a “balcony solar” inverter were to NOT cease to energize upon loss of grid and stay islanded, then voltage is introduced to the building’s/community’s shared local distribution system. If work were to be done on that portion of the distribution system or grid where lineman and wireman expect conductors to be de-energized, then you might have injuries as a result. Now, you may be able to say that lineman and wireman should always test for presence of voltage prior to doing work, and as a solar engineer I would absolutely expect folks to do this, but that’s not always the case. People cut corners. And in the event that certain crews cut corners, don’t check for voltage and investigate where the voltage source is, and start touching wires and introducing paths to ground, people can get seriously injured or die.
You may think that because solar panels are current-limited that this fact protects workers in the event of becoming exposed to live voltage, but any combination of voltage and current can kill.
I’ve always wanted DRM for my inverter.
In the context of safety, this is a good thing. Skirting DRM on movies or TVs won’t mean you injure yourself or others or worse. Skirting inverter settings can cause inverters to operate in ways that are unintended, and could hurt people. These things are not the same, and it’s concerning that you can’t see the difference.
Also, having locks on settings means that other bad actors are deterred from changing those settings maliciously, whether intentional or not.
There is not substitute for a qualified person operating and maintaining an electrical system, regardless of voltage.
I know it because it’s in the spec necessary for licensing. It shuts off in under 20 ms so you can’t even get shocked by the prongs of the plug if pulled out.
It is a commercial product, connected to the grid via a standard schuko plug, sold in Germany. It has to be compliant with the local law to be sold legally.
So you can’t buy raw solar panels or inverters in Germany?
Sure you can. Solar panels will be fried by grid voltage more or less immediately if you connect them directly to a wall socket and become useless.
You cannot buy a PV inverter in Germany (entire EU really) that doesn’t automatically shut off if it doesn’t detect a frequency to sync against from it’s AC side, unless it can run off-grid in which case it has to disble the grid connection within the same 20ms.
You cannot buy a PV inverter in Germany (entire EU really) that doesn’t automatically shut off if it doesn’t detect a frequency to sync against from it’s AC side, unless it can run off-grid in which case it has to disble the grid connection within the same 20ms.
So you can’t buy a grid-connected inverter with off-grid capabilities? Because the inverter has no way to tell the difference between the grid being off, and being off-grid.
Hmmm, I wonder how this would affect things in the future where this is widely used.
I.E. if you had both widespread solar usage and some kind of large blackout, would it be hard to get all your solar back online because it’s all in the “waiting for the grid” state? And the grid can’t come back at capacity because all the solar it’s expecting is out?
I assume people smarter than me have this figured out, but just a random thought if anyone knows more.
Not just solar - most grid-scale generators have this problem. “Black start” is the search term you want to look for, and Practical Engineering has a good video on the subject.
Basically, only a relative few grid generators are actually capable of black starts. The rest need the grid to be already functioning before they can tie in and start producing.
I had a chat about this with a friend who works for the national grid (UK).
Apparently the problem is keeping the grid balanced and stable. Basically, the grid struggles to react fast, so they plan ahead. Things like large scale solar can provide predictions on output. Home solar can’t.
When clouds pass over an area it can cause slumps and surges in the local grid. The more home solar, the worse it gets. The current grid is designed to work top down, with predictable changes in demand. It needs upgrading to deal with large scale bidirectional flows.
The plug in units are (potentially) even more ropey. If used properly, they are no worse than normal home solar. Unfortunately, being cheaper, there are worries over the microinverters not shutting down. Either due to the manufacturer cheaping out, or turning on an “off grid” mode.
There are also worries about overloading household circuits. Back feeding bypasses the household circuit breakers and RCDs. They could overload wall wiring and cause fires, or stop an RCD tripping, allowing for a person to be shocked.
I don’t know how much this would apply to the American Grid, but I would imagine it would be worse. Your grid is older and larger. You also use 120VAC which makes the current overload issue a lot worse.
You also use 120VAC which makes the current overload issue a lot worse.
Voltage inside of residences is 120v AC, but its 240v thats delivered to each house. I think a bigger difference is that in the USA that 240v AC is single phase where I believe (Germany included) many nations in the EU are 3 phase.
The USA does have 3 phase power for most commercial applications though.
It’s worth noting that this is talking about plug in solar, so would be at standard mains voltage.
1kw would be around 4A in Europe, but 8A in the USA. Also, since resistive losses scale with I^2 that’s 4x the heat dumped in the walls.
At least in the UK, they tend to run 3 phase to a road, but only a single phase goes into a given house. You need to get a special hook up to get 3 phase to a domestic premise, and they don’t like doing it.
It’s worth noting that this is talking about plug in solar, so would be at standard mains voltage.
Thats fair.
At least in the UK, they tend to run 3 phase to a road, but only a single phase goes into a given house. You need to get a special hook up to get 3 phase to a domestic premise, and they don’t like doing it.
TIL about the UK electrical system. Thanks!
I’m at the edge of my knowledge but that sounds like it matches the USA system (for the number of phases).
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.
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.
I mean, it makes sense to me that consumers can’t be pumping energy into the grid with no way to cut it off, but I’m not a lineman or some sort of civil engineer or whatever.
But if I were a lawmaker, I’d be on the phone with the Germans, who have 1.2M of these connected, and figuring out if and how they’re doing it safely. But lawmakers seem to be somehow incapable of reaching out to people who know fuck all about anything.
The microinverters stop feeding in if grid goes down. So it’s safe.
What happens when someone makes an unsafe backfeed into a downed grid and then other nearby inverters detect the current and bring themselves back online? Is there a way to detect if the load is being delivered from the utility vs from incorrectly configured solar or generator installations?
Some others are arguing back and forth about this elsewhere in the thread and I see the reasoning: unpermitted systems could accidentally energize isolated portions of the grid during downtime, which might trick properly installed systems to also come back online, and you have a runaway effect where there is enough current present to allow addition safety systems to be fooled.
There isn’t any data transmission over the wires; there either is current, or there isn’t. Arguing over permitting is moot - either safety systems can handle this scenario already, or they can’t.
All paperwork does is slow the relief of dependence on the utility, which hurts their profits.
The same thing that currently happens when somebody does that with a gas generator? Linepersons get zapped… people get sued… etc…
That’s very wrong. Not only can you extend Ethernet in your own home using your power outlets, the power companies have been reading meters this way for decades.
Kinda seems like something you might want to avoid…
Obviously. I was just pointing out that it isn’t an issue unique to solar.
It is unique to “balcony solar”. Typical solar systems require permits and inspections before connecting.
No it isn’t. The same thing happens with the kind of gas generators you can get from your local hardware store all the time.
As I mentioned several times elsewhere, gas generators also typically require permitting.
How do you know? In a typical solar system, you have to have a permit, which requires an inspector to come out and ensure everything is configured correctly and safely. These don’t require any permits, which is great for making them more affordable and accessible, but there’s also no one coming around to make sure that anyone is doing it safely.
Easy check, grab a voltmeter and do it yourself.
Pull the plug, set voltmeter to AC, and read the voltage across the prongs. If you get anything over the usual float voltage you get from just holding the probes ungrounded, then you have a problem.
By “you” I did not mean your personal solar system. I mean how does the utility know that other users that have systems connected are doing so safely?
The PRODUCT is designed to stop feeding OUT the plug if it doesn’t detect CURRENT from the socket. AC is alternating current so it pulses on and off so the solar system is doing the same. It’s turning on and off quickly and seeing if it gets power back and if it detects no power incoming it shuts off the power from the solar. It’s quite simple and ingenious.
I am not asking how the technology works. I am asking how the utility verifies that people are using compliant products.
“The utility” has never had a way to prevent you from doing something dangerous with your wiring or with the electricity they send you. The best we’ve managed has been to encourage appliance manufacturers to design their products with safety in mind, through the UL program (which is voluntary). This is why the writer talked to the “vice president of engineering at UL Solutions.”
Yes they have. It’s called permitting.
Inverters in the US are all listed to UL1741-SB which dictates that they shall cease to energize their AC outputs if they sense an absence of grid voltage.
Now, one thing people are ignoring is that UL1741-SB allows for islanding protection, and the disablement of it. If an inverter has its settings changed such that islanding protection is OFF, then the inverter will keep sending power to the “grid” because it thinks it’s operating on a microgrid that was previously disconnected from the larger grid via a Microgrid Interconnection Device (MID).
The settings these inverters have are user-settable, which means they need to be checked by a qualified person, either a contractor, engineer, or inspector. These settings must also often be checked by the utility you’re interconnecting to before they allow you to energize, so usually all of these parties have eyes on the inverters’ settings and can stop work before energization until things are corrected.
Ultimately I agree with you. If we don’t want to have to need inspections for every solar installation, especially residential ones and especially where plug-and-play solar modules are used, then inverters need to have their settings pre-configured for the grid code in the factory that then cannot be changed by the user or operator in the field. That would be a way to shoe-in this kind of installation.
Hard setting grid codes into inverters prior to shipping to site might be overly conservative though, especially as utilities change their grid codes over time. You need to have a way to update those settings, which could be using a wireless portal hosted by the inverter OEM with credentials made only available to the OEM. Problem with this is that then you shift the burden of configuration to the manufacturer which already has a ton of other UL standards as well as rules and regulations to follow.
What do y’all think?
I agree with everything you said except shoe-in, because it’s shoo-in.
But you articulated (better than I was going to) the number one issue. Power companies need insurance and their insurance will be affected if ordinance permits basically unchecked generators being plugged into the grid. And before anyone says it, you are not allowed to just plug your generator into your house. Does it happen? Yeah, people have been dumb since day one.
But there are transfer switches that allow for this operation in a safe manner, and the easiest way to deal with this is to have them installed by default in new construction, and to provide incentive for upgrading your panel to include one.
No, they are absolutely not. I don’t know where people are getting this idea. Many inverters aren’t even UL listed. There is absolutely no requirement for them to be. If that were the case, off-grid inverters wouldn’t even be allowed to exist. I own several that do not have this capability and are not UL listed.
Not in the case of Utah’s new “balcony solar” laws. That’s the problem.
Oh goodie, I’ve always wanted DRM for my inverter.
I think it should just require a permit, like every other solar installation. Unless we can provide data to show that it’s not a problem in existing areas where this is common, and we research and follow their regulations.
Yes but many inspectors and insurance companies won’t want you to install electrical equipment on “real property” or buildings if it isn’t UL as that falls into the scope of AHJs and insurance providers. If there’s something that has the potential to start a fire, you need to have safety certifications so operating the system not only reduces the risk of fire, but also selling the house in the future to a new owner doesn’t come with excess burden on behalf of the next insurer.
If your solar system is off-grid AND off-building, I see no reason that you need to have a UL listed system.
This is of course dependent on local AHJs and utilities, but UL 1741 covers both standalone (off-grid) and grid-interactive (on-grid) inverters. If you’re choosing an inverter manufacturer that makes non-UL listed off-grid inverters, I would probably be suspect of their products’ quality as it’s easier to gain UL listing regardless of how the inverter is used: off-grid or grid-interactive.
That is a problem. Off-grid inverters that aren’t certified to UL 1741-SB aren’t required to have anti-islanding protection that cuts the inverters off if there’s an absence of grid voltage. If a “balcony solar” inverter were to NOT cease to energize upon loss of grid and stay islanded, then voltage is introduced to the building’s/community’s shared local distribution system. If work were to be done on that portion of the distribution system or grid where lineman and wireman expect conductors to be de-energized, then you might have injuries as a result. Now, you may be able to say that lineman and wireman should always test for presence of voltage prior to doing work, and as a solar engineer I would absolutely expect folks to do this, but that’s not always the case. People cut corners. And in the event that certain crews cut corners, don’t check for voltage and investigate where the voltage source is, and start touching wires and introducing paths to ground, people can get seriously injured or die.
You may think that because solar panels are current-limited that this fact protects workers in the event of becoming exposed to live voltage, but any combination of voltage and current can kill.
In the context of safety, this is a good thing. Skirting DRM on movies or TVs won’t mean you injure yourself or others or worse. Skirting inverter settings can cause inverters to operate in ways that are unintended, and could hurt people. These things are not the same, and it’s concerning that you can’t see the difference.
Also, having locks on settings means that other bad actors are deterred from changing those settings maliciously, whether intentional or not.
There is not substitute for a qualified person operating and maintaining an electrical system, regardless of voltage.
Agreed
…why would anyone care what those people want?
No you don’t.
You’re missing the point. Nothing is stopping anyone from installing off-grid inverters (or any inverter at all) in an on-grid system.
Have you ever looked at “top sellers” on Amazon? Most people do not care about quality, they just buy the cheapest shit possible.
I see the difference, I just don’t care. It’s concerning that you can’t see the potential for exploitation, both from corporations and governments.
I know it because it’s in the spec necessary for licensing. It shuts off in under 20 ms so you can’t even get shocked by the prongs of the plug if pulled out.
What license? Who is coming to verify your license?
It is a commercial product, connected to the grid via a standard schuko plug, sold in Germany. It has to be compliant with the local law to be sold legally.
It all shouldn’t be so difficult to understand.
So you can’t buy raw solar panels or inverters in Germany?
It’s not, which is why I’m not sure why you’re struggling.
Sure you can. Solar panels will be fried by grid voltage more or less immediately if you connect them directly to a wall socket and become useless.
You cannot buy a PV inverter in Germany (entire EU really) that doesn’t automatically shut off if it doesn’t detect a frequency to sync against from it’s AC side, unless it can run off-grid in which case it has to disble the grid connection within the same 20ms.
So you can’t buy a grid-connected inverter with off-grid capabilities? Because the inverter has no way to tell the difference between the grid being off, and being off-grid.
Hmmm, I wonder how this would affect things in the future where this is widely used.
I.E. if you had both widespread solar usage and some kind of large blackout, would it be hard to get all your solar back online because it’s all in the “waiting for the grid” state? And the grid can’t come back at capacity because all the solar it’s expecting is out?
I assume people smarter than me have this figured out, but just a random thought if anyone knows more.
Not just solar - most grid-scale generators have this problem. “Black start” is the search term you want to look for, and Practical Engineering has a good video on the subject.
Basically, only a relative few grid generators are actually capable of black starts. The rest need the grid to be already functioning before they can tie in and start producing.
You turn on parts of the grid at a time.
https://en.wikipedia.org/wiki/Black_start
Yes, starting up a downed grid is a difficult problem. Recovering from a large scale failure could take weeks. Longer, with blown transformers.
I had a chat about this with a friend who works for the national grid (UK).
Apparently the problem is keeping the grid balanced and stable. Basically, the grid struggles to react fast, so they plan ahead. Things like large scale solar can provide predictions on output. Home solar can’t.
When clouds pass over an area it can cause slumps and surges in the local grid. The more home solar, the worse it gets. The current grid is designed to work top down, with predictable changes in demand. It needs upgrading to deal with large scale bidirectional flows.
The plug in units are (potentially) even more ropey. If used properly, they are no worse than normal home solar. Unfortunately, being cheaper, there are worries over the microinverters not shutting down. Either due to the manufacturer cheaping out, or turning on an “off grid” mode.
There are also worries about overloading household circuits. Back feeding bypasses the household circuit breakers and RCDs. They could overload wall wiring and cause fires, or stop an RCD tripping, allowing for a person to be shocked.
I don’t know how much this would apply to the American Grid, but I would imagine it would be worse. Your grid is older and larger. You also use 120VAC which makes the current overload issue a lot worse.
Voltage inside of residences is 120v AC, but its 240v thats delivered to each house. I think a bigger difference is that in the USA that 240v AC is single phase where I believe (Germany included) many nations in the EU are 3 phase.
The USA does have 3 phase power for most commercial applications though.
It’s worth noting that this is talking about plug in solar, so would be at standard mains voltage.
1kw would be around 4A in Europe, but 8A in the USA. Also, since resistive losses scale with I^2 that’s 4x the heat dumped in the walls.
At least in the UK, they tend to run 3 phase to a road, but only a single phase goes into a given house. You need to get a special hook up to get 3 phase to a domestic premise, and they don’t like doing it.
Thats fair.
TIL about the UK electrical system. Thanks!
I’m at the edge of my knowledge but that sounds like it matches the USA system (for the number of phases).
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.
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.