question

hypercoffeedude avatar image
hypercoffeedude asked

Phoenix 24/1200 inverter energy use (watts) reading high. Bad calibration?

I have a Victron Phoenix 24/1200 inverter and I'm using Venus OS and viewing the Remote Console screen. The readings I am getting from the inverter are almost twice what I am actually consuming. Example: 160w AC Load shows up as 372w. I've used a few different external energy meters to confirm the actual load reading is correct. I've also tried a standard 60W incandescent bulb, which shows up on the inverter as 204W. Is there any way to calibrate the internal sensor to provide better accuracy?

Phoenix InverterEnergy Meter
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2 Answers
Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

Unfortunately not. The accuracy of the power readings on the VE.direct inverters is not very precise.

It gives some indication, but there is a large margin of error.

In the past I have proposed an alternative way to display the power reading given block bar ranges instead of Watts.

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hypercoffeedude avatar image hypercoffeedude commented ·

That's unfortunate. Do other inverters such as the Multiplus and Quattros experience this issue on either the inputs or the outputs?

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Guy Stewart (Victron Community Manager) avatar image Guy Stewart (Victron Community Manager) ♦♦ hypercoffeedude commented ·

As Paul mentioned, the Multiplus power readings are much more accurate, though still no substitute for an actual energy meter.

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Paul B avatar image
Paul B answered ·

The Multiplus Units and the Quattros being the bigger units may have some rounding error and overhead as well, but basically the figures are correct, but not 100% CORRECT but within around 1 to 2 percent I would guess at.

dont forget to measure the INCOMING Battery power as well and compare to the AC output using a Good DC Clamp meter as it will be diferant to the AC output as there is also inverter overhead to allow for, the differences are normally not double but they will be higher at the lower end of the load scale % I would think.

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hypercoffeedude avatar image hypercoffeedude commented ·

I have used a known good DC/AC clamp meter and a calibrated Sonoff S31 (running Tasmota) as well as a kill-a-watt style meter which also showed the same AC wattage. Currently, I am running a 43W or 47VA (0.391A * 120) AC load on the inverters output and I show 59W ( 2.11A * 28.2V) DC load from the batteries to the inverter. There are no other DC loads. Between the two readings, I can assume the reason for the DC load being higher is correct due to the inverters no-load current added to any efficiency losses.

With that said, I really expected more from a $400+ product that has an option to show such readings. I don't even expect it to be dead on, but if it's going to be that far off from the correct value, perhaps there needs to be a user accessible calibration option in case of problems like this one has. The inverter is currently reading at 108W which is 2.5 times the correct value. That to me is unacceptable and I will absolutely have to use external readings.

Might there be any way to modify any scripts in Venus OS or otherwise send the correct value to the VRM monitor screen? My Sonoff S31 is connected via MQTT and Home Assistant so I could easily grab the correct value from there if I had a place to send it to. I would really like to use the built in tools to visualize the system.

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