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Comment by ssl-3 | Hacker News Reader

If the question is "is it an 'actual feature' or is it 'necessary behavior'" then the answer is: Yes.

Simple grid-tied microinverters are completely incapable of doing anything without a grid to work with, and this is necessary: A non-synchronized AC generation source can't survive long before becoming an expensive puff of smoke instead.

Anti-islanding is an actual feature that is also inherent in the design of grid-tied inverters: When there is nothing for them to sync to, they output nothing.

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It’s not necessary in that the inverters need to support it (they could just do randomly staged power ons, and the first one could pick the phase).

However, there’s a problem in addition to electrocuting utility workers (the ones around here assume islanding during outages, so that’s less of an issue now).

Say you plug the microinverter into a 16A 120V outlet in the US, and the power goes out while you’re running a 240V 40A clothes dryer. The island is definitely going to collapse at that point, and might do bad stuff on the way down.

Even in that weird non-existent corner case instance, it is a necessary function because a hypothetical microinverter is completely and utterly incapable of kickstarting a grid.

You could totally have half a dozen microinverters scattered around your household, connected to each other but temporarily not to the neighborhood distribution network.

I could have that; many homes in the world do have that. And when the grid dies, the microinverters all die with it.

Possibly you have misunderstood.

Can you elaborate? Which part is it that you think I may have misunderstood?

What problem (or solution) is the concern, here?

A hypothetical microinverter is completely capable of kickstarting the "grid" within a single house. You can try it yourself: get a 2000-watt car inverter, connect it to a car battery, turn off your house's main circuit breaker, and plug a suicide cord (male to male) between the car inverter and one of your house's outlets. The electrical appliances in your house will work fine unless one of them starts trying to draw more than 2000 watts (or, as hedora says, unless you're powering only one phase of a split-phase system). This is dangerous: if someone turns the main circuit breaker back on while in this setup, the car inverter will probably be destroyed and may start a fire. But it's far from a technological impossibility. It's achievable even with redneck duct-tape-and-baling wire engineering.

The grid-tied microinverter cannot do this on its own. It is incapable.

A person can add other things to the scenario and the microinverter may elect to play ball, but it is simply incapable of kickstarting bloody anything on its own.

Are there any other wildly imaginative corner cases you'd like to explore that have nothing at all to do with balcony solar, as it is implemented in Germany?

I was rebutting your incorrect assertion in https://news.ycombinator.com/item?id=45487471 about what hypothetical microinverters were or were not "utterly incapable" of. The comment you have just posted is irrelevant to that.

The design features of currently existing microinverters are irrelevant to hedora's point about what microinverters could be designed to do, except insofar as they constitute an existence proof. (Obviously something is possible if it's already being done, but the inverse is not true.)

Furthermore, unsafely plugging your house wiring into a cheap generator or car inverter isn't a "wildly imaginative corner case", it's a common enough practice that there are YouTube videos warning people against doing it, because it's unsafe and in most places illegal, and also explaining how to do it: https://www.youtube.com/watch?v=9kjpS1vfGio https://www.youtube.com/watch?v=ZiicSQZqGd0 https://www.youtube.com/watch?v=DIhzy6hfvyM as well as safer approaches: https://www.youtube.com/watch?v=ydRveyXkf4M https://www.youtube.com/watch?v=ZmmhOXsIRjw

"A hypothetical microinverter" could contain plastic explosives rigged to blow up your house. Hypotheticals are fine but to be clear you've drifted away from the topic - balcony solar panels with built-in microinverters, purpose built with arc and grid detection mechanisms. But yes do not rig a car inverter to your home outlets.

Thanks, I think that answers my question. It seems like there is a lot of regulation to enforce a behavior that was already necessary for microinverters to work at all. But given the risk (utility worker electrocution during outages), I also understand why utilities are extra-conservative about it.

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