I have two questions for the community. 

1. Assume I have 2 Axpert inverters connected in parallel, how easy would it be to switch one inverter on/off to reduce the total quiescent (idle) power consumption at night?  I would not need to perform some start-up synchronization routine?  Would it be as easy as flicking the switch?

2. Would it be possible to put an Axpert inverter into sleep/standby mode remotely?  Either by means of a dry contact NO/NC wire loop, or supplying a TTL-like control voltage or by issuing a command over the communication bus?

I am asking the latter question to see if it would be possible to design a small interface that would allow an inverter to be taken out of standby mode on demand.  One could design a circuit to check for any loads connected to the 230VAC circuit.  If the impedance is below a certain threshold, this could be read as a "power-is-requested" event and then this interface box would wakeup the inverter by using an opto-coupler, relay, or issuing a command over the communication bus.

I am mainly interested in the Axpert inverters, but you can also comment on other inverters.  Perhaps this sort of function is a standard out-of-the-box function on some makes of inverters.

I know that at least some Victron inverters have a low power mode where they energize the output every few seconds and if the current drawn is over a threshold, will switch to normal operation.

Perhaps the Victron function could be implemented in software only, on a small Arduino or Pi.  However, the Victron method is not ideal, I would prefer to inject a high frequency low voltage signal into the net and measure the impedance with hardware.

Call me crazy, but my ideal future solution would be:

1.  Have all my house lights run from 12VDC
2. Have USB-C power available in every room for PC/TV/Laptop and other common consumers
    The  USB-C-PD standard supports loads up to 48V and 5A - that is up to 240W (!)  A 24 or 48VDC backbone could be used.
3. Use an inverter only for high power loads, standby by default, active only when requested by a load

I am no green tree-hugger.  The WEF directed climate change bullsh!t is going to become the biggest money making racket by the Elites.  But I do have respect for power.  Even a small 3 KVA Axpert wastes 40W.  People that don't think it is much, I recommend climbing onto an exercise bicycle with a generator and see for how long you can generate 40W on a continues level.  I doubt if you can keep it up for more than one or two hours.  At the moment, just about everyone is still on Eskom.  So for the 15 hours or so no/low light conditions, you use Eskom to keep your invert(s) warm and cozy.  If you are 100% off-grid, those 40 to 80W need to be drawn from your batteries.  Do the sums.  Batteries are just too damn expensive to waste on keeping Inverters cozy - me thinketh.
 

1 hour ago, Modina said:

1 hour ago, Modina said:

I would not need to perform some start-up synchronization routine?

1. Assume I have 2 Axpert inverters connected in parallel, how easy would it be to switch one inverter on/off to reduce the total quiescent (idle) power consumption at night?  Would it be as easy as flicking the switch?

It's moderately complex to do it in firmware. Weber and I figured it out for the older Axpert MKS 1 models.

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2. Would it be possible to put an Axpert inverter into sleep/standby mode remotely?  Either by means of a dry contact NO/NC wire loop, or supplying a TTL-like control voltage or by issuing a command over the communication bus?

It's implemented in "fully patched" firmwares, like 73.00e, 74.40e, and 72.20e.

As for hardware, I'd have to check, but possibly wiring a Normally Closed relay contact in series with the power switch might do it. it might even reduce to a lower power level than our firmware command.

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I would not need to perform some start-up synchronization routine? 

The firmware already does a lot of checking before powering down and when it powers up. So I believe that's all covered.

Do Axperts have a low power or "search" mode ?

If they do, maybe that would be easier... I'm not sure how this mode works when in parallel. But if only one can have this mode, you could use a simple AC timer to cut the output from the second inverter, and then it won't sense a load, and go into low power mode.

 

Just a theoretical suggestion, haven't tried it with parallel inverters.