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this post was submitted on 12 Mar 2026
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The microinverters stop feeding in if grid goes down. So it's safe.
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.
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.
Assuming its not cheap piece of crap that isn't UL listed and that's where the problem is.
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.
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.
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.
Or you buy it in Aliexpress/Temu and it will have whatever it will have, no policeman is going to come check if the panel they see from the street has a stamp or not.
But if your house burns down because of your unlicensed configuration, the insurance won't pay, and if people got hurt there will be a criminal investigation.
You are only allowed to sell inverters approved by VDE
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.
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?
Utilities must approve power export to the grid, even if you do the physical installation 100% off the books. It's called “Permission to Operate”, which requires permits and passed inspections. You can’t just unilaterally add shit to the power grid.
https://www.energysage.com/solar/solar-interconnection-what-you-need-to-know/