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.
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.