Pre-Order Discussions

That's what I already discussed earlier, where the throttle regulation can be configured to offset any amount of power.  Or none at all.

You're still missing the crux of the backfeed issue, though.

A somewhat defective example would be driving your car: you're zipping along pretty hard, and without any warning, someone pops the transmission in neutral ("big load turned off").  The engine RPM will hit the rev limiter pretty quickly (i.e. energy is getting directed elsewhere than the "load" of the vehicle)--and I can guarantee you that you won't be able to react fast enough to prevent that from happening.  (This of course assuming that you have no idea when or if the transmission will be thrown into Neutral, like the inverter which has no idea when or if a load will disappear.)

Obviously, hitting the rev limiter is not ideal (and neither is backfeeding for an inverter).  And obviously, the inverter can react a whole lot faster than a person.  But you should get the point 😉

okay I understand now, thanks for your time and patience

How well can the 12k handle oven loads? Our electric oven cycles the oven on/off to maintain proper temperature so it hits the inverter with 4000+ watts when it does that. It makes the lights dim a bit, makes me wonder what the sine wave/voltage look like when it does it...Currently using smaller inverters 4*4400 watts. Wondering if one large transformer would help the situation. 

4x inverters to run a big load...yeah, I can see that resulting in a dimming under load, as a result of sync and wiring resistivity differences.  I'm just curious, care to mention make/model?  And if you can confirm AC output voltage drop with a multimeter when the oven element's on?

The GS 12kw will maintain output voltage up to full load and beyond, attempting to maintain +/-0.5vAC.  So you would definitely see a "flicker" when the element turns on and off--but not a sustained "dimming."  It is worth noting that the battery sag under load will comprise most of any "dip" that an inverter needs to deal with.  In other words, the more the batteries sag, the more the inverter has to work to react.

Magnum ms4448pae, 100kwh lfp battery. The magnums have a IE transformer vs. the newer toroidal transformers. Not sure if that makes a difference. 

Magnum ms4448pae, 100kwh lfp battery

Why so much battery  and how many solar panels   to keep them charged   ??  

WOW !!!    Able to  Parallel  4  inverters  in split-phase  mode  and 3 years warranty ???   

about 20kw panels. All electric off grid. 4 parallel is the max. I think magnum is going out of business or something. Seems hard to get product right now, and they seem less than responsive judging by the forums. Maybe they just had a hard time with supply...Idk. Genetry 12kw sounds like a good option, but waiting for the 2nd run. 

Looks like the voltage drops to 220v from 240 when it comes on, and goes from 240v to 250v when it turns back on. measuring with a digital multimeter.

So a 30v swing...that's quite inexcusable!  Could likely have something to do with their paralleling setup--and especially if they did the "simple chintzy" way of paralleling, could actually have a lot to do with differing lengths of both battery cables and AC output cables.  If their manual has any sort of warning about these things, then I  know exactly how they implemented parallel functionality!

I can tell you this, a Genetry inverter with a Rev. C control board (which most of them are!) will not do that!  It should be able to hold within +/-2v; I could easily make it tighter, but at the risk of regulator oscillations.  Obviously, loads turning on and off will have a brief "glitch" as it corrects.

I might have said it wrong, it's not oscillating, when the load comes on it drops by 20v then stabilizes. When the load goes off it goes to 250 then stabilizes at 240v. Seems like a lot to me. Glad to hear that 12k should do a better job. I set it up with 2 separate circuit boxes so should be good if I want to use 2 separate 12k systems hooked to the same battery down the road. Also went over every wire connection so everything is tight/torqued. 

Magnum uses cat5e cable to a router, and what look like telephone cables. They do say not to go more than about 15ft on the battery cables to the inverter. They also talk a lot about the inverters needing to be on the same battery bank.  

Hmm...how much is the voltage at the inverter battery terminals sagging when the load pops on?  You can fairly easily calculate how much sag will result on the output, seeing as the transformers are a fixed ratio (although the SPWM "throttle" does determine the actual input voltage to the transformer--it's actually fascinating how mathematically precise the whole process can be!)

for example, if you're at 240v output, assuming 53v input on the battery, you can very crudely estimate 240 / 53 = multiplier of ~4.53, so if we take the "low" of 220v / 4.53 = 48.56v....

...oh, that's a bit bigger of a battery voltage drop than I expected!  Unless your batteries are dropping 4.44v under load (and then popping back up again afterwards), I could consider inverter design/regulation to be a possible culprit here.

Now, if your battery voltage (at the inverter DC terminals) is dropping 4.44v when the oven element turns on...then a GS12 will not be able to do any better with how far the AC output voltage briefly dips/surges under load.  As far as regulation response...there's always the hope that I'll be able to find some magic algorithm that avoids oscillations, but can correct for any load change within 1-2 cycles.  Right now it's a bit slower than that.

Looks like 0.34v of sag on the DC side, then the dc voltage is staying at 50.71v while the load is running. 

So started at 51.05v dropped to 50.71 volts and stayed there. 

So your batteries, breakers and wiring are doing very well...those aren't the issue.

This makes the 20v output sag quite unexplainable from the Magnum inverters...unless their transformers have a very large internal resistance, causing the large sag.  But that'd result in a heap of heat generation under load...do they run very hot when loaded?

How long do the inverters take to restore desired output voltage when the oven element pops on and off?

(I mean, I don't want to just blanket say, "GS inverter would do better" without thoroughly investigating the environment--because any inverter will have to deal with the same realities.  It's just how said realities are dealt with that can affect the outcome.)

It takes about a second to get back to the 240v. I don't think they are running too hot under load. I did beef up the neutral, but since it's a 240v load I don't think that would affect anything. Could be that my expectations are too high 🙂 The transformer shows a max of 136f for today and the FETs show 107f for today. 

Yeah, that's pretty slow.  I'd expect around 1/4 second to be "median", with "best possible case" being 1-4 AC cycles.

Not sure why.  You did mention you have 4 Magnum units running in parallel; I'd suspect that has a lot to do with it.