I'm trying to get confirmation from Victron that the AC-In connection cannot send power back out to whatever is connected to it i.e. Generator, AC shore power, etc.
asked
Confirm that MultiPlus AC-In is "one way" only and cannot send power out
In it's default factory configuration it does not allow backfeed. If AC is present at the input then this energy will be used to supply loads and / or charge the battery.
A conscious decision needs to be made, in VE.Configure software, to apply a grid code to the unit which would then enable backfeed if an ESS assistant is loaded for example.
No grid code means that the unit cannot run "grid parallel" no backfeed is possible and the unit acts like an appliance.
Section 2.4 (page 3) of the manual states:
Here is a link to the manual:
https://www.victronenergy.com/upload/documents/Manual-MultiPlus-II-12V-24V-48V-3k,-5k,-8k,-10k-230V-EN-NL-FR-DE-FI-SV.pdf
I have a quattro with ac coupled pv. On sunny days when the load is high the quattro will call for the generator to run. If the load suddenly switches off the ac coupled pv will momentarily push power out the ac input to the genset until the frequency shift has time to ramp the pv back. If your gamed to try it you can see it all happen on vrm.
I meat to say the frequency shift can't ramp the pv back. (Gen is running seting frequancy)
I'm not planning on using AC coupled PV but will use an MPPT Charge Controller connected to the Battery and Inverter, so hopefully this mitigates the problem you mentioned Andrew?
Image Caption
Note the negative input power.
That is with AC-Coupled PV right? Then that behaviour would be expected if the generator is running (backfeed relay closed) and the system is suddenly unloaded. That reverse energy would be coming from the PV Inverter and not the MultiPlus. The control loop would respond to this change and then the MultiPlus can load up to charge if the battery is not full.
If you have AC-Coupled PV then you either have permission from the network operator or you are off-grid in which case the network operator is not involved.
The OP is talking about a DC-Coupled system. They have no interest in any AC-Coupling at all.
The original question asked right at the start was "can the multi send power out the ac in" with absolutely no mention of either ac or dc coupling. The very next comment made was "in its default configuration it does not allow back feed" and then the statement "no gridcode means the unit cannot run grid parallel". I just think at this early stage of the discussion your comments were a bit misleading given at this stage we did not know if things were ac or dc coupled.
We're also seeing current apparently being sent to the grid, in our case from a MultiPlus 48V/3000/35A in a narrowboat. We have no ESS and no solar panels. We are connected to a shore line from October to March, with current limit set to 6A on our Multi Control GX Panel due to limited capacity of the shore line. We leave the boat ring main (AC out) on when we are away but nothing plugged in. Returning after 5 months we plugged in the fridge but nothing else. That night we noticed that the MultiPlus fan was running loudly; the mains light was on steady and the inverter light was flashing, indicating that PowerAssist is active; and our main battery bank (400 Ah) was running down unusually fast. If we switch the MultiPlus off and on it returns to normal operation and bulk charging. If we leave it running, it stops PowerAssist after about half an hour, with the battery at about 95%, and resumes bulk charging. While PowerAssist was running, the VRM display from our Venus GX showed current going out to the grid (AC In was set to 'Grid' in set up; we have now changed it to 'Shore' as that seems more appropriate). We left the boat for a further 2 weeks with fridge off and the system operated normally, with no PowerAssist events. We returned and switched the fridge on, and the same things happened as before, 3 nights running. Trying to understand what is happening, I switched on our immersion heater and a hair dryer and sure enough the same things happened. However, this time I was watching the VRM and saw that current continued to flow IN from the grid while the immersion and hair dryer was on: presumably this is the intended behaviour. However, when I switched the hair dryer off, PowerAssist continued to operate although probably no longer needed and less current was being drawn from the shore line. And when I switched the immersion off as well, PowerAssist still continued but now current was flowing OUT to the grid, and continued to do so until I switched the MultiPlus off and on. So it seems that there is a substantial delay in the unit reacting to the reduced AC load, and during this time, the surplus current produced by PowerAssist is going to the grid, or at least that's what the Venus GX and VRM are showing. This seems very similar to what was described in the preceding posts. The fridge does not normally pull much current, so presumably the events it causes are due to short-term spikes in load when the fridge motor starts up. Our questions are: 1) is our MultiPlus really sending current out through AC-In and if so, why, 2) is our MultiPlus or Venus GX faulty and in need of repair? 3) if we go away and leave the boat on shore line and fridge on, might it damage our battery bank or will it always resume charging before too much is lost? Any advice will be very welcome.
Attached are screenshots from the VRM:
1. Immersion on, hair dryer off.
2: Immersion + hair dryer.
3: Immersion only, hair dryer switched off.
4: Immersion off - current going to grid.
5: After switching MultiPlus off and on: charging resumed.
Presumably your Multiplus grid code is set to "None". I have a narrowboat but luckily 16A shorepower so never had power assist working. I do not think that the "Grid" or "Shore" option actually affects anything, but I likewise changed to "Shore"
Thanks for response. Where do I see/set grid code? Cannot find it in VRM portal.
You need a MK3 interface and VE configure software. You also need the correct grid code
So is it possible that the behaviour I'm seeing is due to incorrect grid code? What grid code would be correct? Should it be set to 'none' - and would this stop current going to grid?
Okay can now confirm our grid code is set to 'None'. Does this mean it should not send current to grid? Why does VRM show it doing so?
