DC Power shows incorrect consumption on unloaded phoenix inverter

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runar-borge asked May 5, '21

DC Power shows incorrect consumption on unloaded phoenix inverter

After some time wondering why my "DC Power Consumption" some times report incorrect values in the dashboard i started trying to figure out why.

System components:
* Phoenix Inverter 12V 800VA 230V
* Smartshunt 500A
* EPEver PC charge controller (reporting to venus)
* Pi3 with Venus os
* 100Ah 12v Lifepo4 battery

While running on battery and no or a small load on the inverter, the "DC Power" reports a power consumption of approx. 23w or 46w more than that the actual power used displayed on the battery shunt on the Venus and in VRM.

Display when inverter is loaded with approx 12w(bulb) + 6w of inverter idle consumption:

(The shunt reports correct all the time, checked with a clamp meter)

I've seen the difference between shunt and dc power to been up to 46w when the inverter is completely idle(ON but nothing connected on AC side)

After some peeking into `dbus-spy` i think i've found the issue, and it seams to be that the inverter reports between 0 and -0.2A load on `AC/Out/L1/I` when idling, reporting -0,1A on 230v will report to -23w of usage and shown as 42w( -1*(-19+-23) ) extra ont the "DC Power" block in the UI. This is also the reason why the issue disappears when the inverter is loaded, as this negative reading then will be gone.

As for now it looks like the current reading on my inverter could be out of sync inside the device, or that it just displays incorrect values when idling... Is there a way to get this reading "in-sync" again (a form of calibration?) or something else that could be done to make my reading more exact? eg. ignore current readings bellow zero from the inverter ? as the inverter have no way of generating back power there should never be a negative value reported on the AC side.

Anyone have an advice for this issue?

Venus OS Phoenix Inverter dc system

screenshot-2021-05-05-at-195853.png (33.5 KiB)

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runar-borge commented · May 06, 2021 at 08:02 AM

i dont know if it is the most correct solution, but i modified my dbus-systemcalc.py to ignore inverter currents lower than 0.0A and it seams to do the trick for me at least. My Inverter can never deliver power back from the AC side so for me this is a working solution: patch follows:

root@raspberrypi2:/opt/victronenergy/dbus-systemcalc-py# diff dbus_systemcalc_orig.py dbus_systemcalc.py
--- dbus_systemcalc_orig.py
+++ dbus_systemcalc.py
@@ -636,7 +636,7 @@
 # DC estimate. This is done using the AC value since these
 # inverters don't provide DC power values.
 inverter_power = 0
-if vedirect_inverter is not None:
+if vedirect_inverter is not None and self._dbusmonitor.get_value(vedirect_inverter, '/Ac/Out/L1/I', 0) > 0:
 inverter_power = self._dbusmonitor.get_value(
 vedirect_inverter, '/Ac/Out/L1/V', 0) * self._dbusmonitor.get_value(
 vedirect_inverter, '/Ac/Out/L1/I', 0)

0 ·

Modifications Space

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Answer 1 · 2021-05-11T10:54:08Z

crownroyal answered · May 11, 2021 at 10:54 AM

I can confirm, that I'm having the same issue. Thank you for that fix. Will try it asap

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Answer 2 · 2022-11-23T13:19:03Z

rpetrovski-forum answered · Nov 23, 2022 at 01:19 PM

Applied a similar fix. Thank you. It's the end of 2022 and still Victron has not done anything about the issue. I'm starting to suspect the VRM isn't as useful as one would hope it to be...

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