question

paul-campbell avatar image
paul-campbell asked

Inverter voltage vs. grid voltage (off grid system)

My multiplus defaulted to 230V, which is perfectly reasonable. I left it at that.


However when it comes out of AC-Ignore, it finds the actual grid voltage is 235-248V. Again nothing seems concerned. When AC-Ignore toggles off the loads voltage rises to 240V from 230V. No big deal, right?


So that's the question. How far off is too far off? Is +/- 10% okay for AC-Ignore transfer switching? Any concerns if that voltage gets to say 20V?


Multiplus-IIvoltage
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3 Answers
Alexandra avatar image
Alexandra answered ·

@Paul Campbell

The inverter synchronises to the grid voltage and the 230v is designed to accept 180V to 265v and invert at 230v (you can adjust that if you want to but it is not necessary).

So from that side if things you will be fine.

It should be inverting at 230v however. How are you driving your AC ignore logic? Does it invert at 230v if you physically cut the incoming power with the AC breaker?

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paul-campbell avatar image
paul-campbell answered ·

Yes sorry, it inverts at 230V fine. I have seen it ramping on load spikes from <200V up, which should be fine.


I have hit it with some odd loads too, just to test it. Like a 300W garden strimmer (800VA inverter). An inverters nemesis, a variable constantly changing highly inductive/reactive load. Not a single PC reboot while I strimmer the lawn, and the multiplus, being set to accept AC if the load hits 700W, did so for 5 seconds each and every time I fired it up and switch back to inverting 5 seconds later, as told to. it also coped with the reactive kick back when it powered down repeatedly. Again the micro-grid circuit never got interrupted.

Note... the battery in system obviously felt differently in this situation. Rightly slapped with full solar, then heavy load repeatedly. Its what I bought it for. Its working for it.

The only oddity is the VA on "no load" "AC Accept". It's showing a 0W power, but sometimes -60VA. I have not independently monitored this, but, I flagged it as odd. It has registered negative ACOut and negative ACIn power. However these are in the 0.000001% type stuff. Like 20Wh over 3 months.

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paul-campbell avatar image
paul-campbell answered ·

Sorry.
AC Ignore: Battery voltage above 25.5V undo at 26V. Load above 700W for 1 sec, undro at 650W for 5 secs.

Standard charger settings are charge 25.5V, float at 25.0V. Basically float the DC loads off mains to prevent low voltage. Later when the second half the battery comes online this will rise to provide a more substansial reserve for grid outages.

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