Downsides of "Seamless Switch" on EG4 18kpv?

I assume to support a faster transfer time in the event of a grid failure that there's some downsides to enabling this setting. Does anyone know what they are? Limited ability to ac couple? Reduced capacity on the load terminals? Reduced efficiency?

Why wouldn't it just be enabled by default if not?

I would assume efficiency losses. Because it must remain in sync with the input.
But, I'm just guessing.

But you inverter always has to remain in sync to have hope to grid assist. Otherwise some magic smoke will happen, OR you can't self-consume.

"In the event of a grid failure" implies it's set to grid assist grid tie when grid is up.

zanydroid said:

But you inverter always has to remain in sync to have hope to grid assist. Otherwise some magic smoke will happen, OR you can't self-consume.

"In the event of a grid failure" implies it's set to grid assist grid tie when grid is up.

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Yeah, i'm guessing it's more about having the inverter online and already feeding the load output? But if that's the case, I'm assuming it means it can't charge from ac at the same time? And there's an efficiency loss? And how does that work with ac coupling? etc etc etc.

I feel like some clarification on the trade-offs would be nice, because if they suck, then maybe it's better that I just buy a small little UPS for my internet router

nuke said:

Yeah, i'm guessing it's more about having the inverter online and already feeding the load output? But if that's the case, I'm assuming it means it can't charge from ac at the same time? And there's an efficiency loss? And how does that work with ac coupling? etc etc etc.

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If you're on-grid you're not frequency shifting. I doubt it will affect AC coupling.

nuke said:

But if that's the case, I'm assuming it means it can't charge from ac at the same time?

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The inverter can probably maintain grid lock in charging mode. There is no fundamental physical reason it can't. You'll have to ask LuxPro/EG4. The physical situation where you can't charge and invert, is if it's ACTUALLY inverting with legit amounts of power. Pretty sure these things can grid form and still charge, otherwise AC coupling off grid would never work. Probably has some tiny helper transistor H bridge for this purpose so that the honking big transistors can be retained for charging.

nuke said:

And there's an efficiency loss?

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It will probably be fixed overhead based (if any) and not % based.

nuke said:

maybe it's better that I just buy a small little UPS for my internet router

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This will probably transfer faster. Inverters in my mind aren't optimized or measured as UPSes. It's a bonus feature if it doesn't glitch your stuff.

@Markus_EG4 or @EG4_Jarrett - do either of you know?
@Luxpower_Gilbert

nuke said:

I assume to support a faster transfer time in the event of a grid failure that there's some downsides to enabling this setting. Does anyone know what they are? Limited ability to ac couple? Reduced capacity on the load terminals? Reduced efficiency?

Why wouldn't it just be enabled by default if not?

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Seamless EPS switching, I feel, should come enabled by default. I select is on every inverter I commission and use.

As far as downsides to enabling the setting, I don't see there being one. Enabling the setting gives us the 10ms switching time.

I also highly recommend the use of a UPS for your routers and PCs. I still need to buy a reliable UPS myself lol

There does appear to be a limitation with that setting and AC coupling unfortunately. Took a few days to figure it out but SS tech was able to remote in and fixed my issue by turning off that setting. Hopefully will get fixed with a firmware update in the future...

My issue:
Even though I enabled the "Charge last" setting to prioritize grid export instead of battery charging (since I have 1:1 net metering agreement, eliminates the inefficiency of multiple DC to AC conversions), the 18k kept prioritizing battery charging anyway. The tech explained that it had something to do with the rapid voltage changes or something (don't quote me on that).
Huge bummer though that I have to turn off that setting. Haven't tried cutting off power since then to see how it impacts my setup but that was the main reason I got the 18k and powerpro bundle was as a seamless battery backup for grid outage tied to my existing microinverter solar system.

I'm not sure I follow - you're saying that with AC coupling, you can't use charge last with "seamless switch" because what? voltage changes?

nuke said:

I'm not sure I follow - you're saying that with AC coupling, you can't use charge last with "seamless switch" because what? voltage changes?

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Not entirely sure if it's truly voltage changes causing the issue, I think that's what the tech said.
But my actual issue is just not being able to use the charge last feature (prioritizing loads > grid > batteries) if seamless switch is enabled because it will still prioritize batteries over grid export if seamless switch is turned on.

I think "seamless switch" means it always keeps the inverter energized (active standby). Let's say you are running off grid power, and there is no need for the inverter to be doing anything. Then, it may turn off the inverter to save a few watts of power. In the event the grid goes down, and the inverter has to start supplying power, then the inverter has to energize (capacitors charge up, etc.). That takes time, and the 4ms transfer turns into 20ms (or whatever the timing is).