question

ppppp avatar image
ppppp asked

Inverter efficiency curves

I'm curious to see specific efficiency curves for various Victron inverters I'm looking at, but my searching has been fruitless. I have a 24v system and am looking for an inverter that needs to run only two loads at 220v: one is 30w constant, the other is intermittent and will peak somewhere around 776w. My concern is that the constant 30w load may fall in the abysmal range of the efficiency curve for many inverters. I don't see any way to avoid this, but I would like a rough number of what efficiency I might expect in this scenario.

inverter current draw
2 |3000

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5 Answers
ben avatar image
ben answered ·

Search for “victron efficiency curve” and have a look at the white paper that comes up. Those curves are for the big models, but the little ones will probably have a similar characteristic shape.

The very tiny, continuous load might be best served by its own dedicated, very small inverter, if every watt-hour counts. Those units have a baseline demand of only ~4W in continuous operation.

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ripper avatar image
ripper answered ·

https://www.photovoltaikforum.com/thread/133886-effizienzkurven-wechselrichter-victron-oder-fahre-ich-mit-2-wechselrichtern-wirk/

Phoenix 24 375 vs Multi 24 3000


Look at the second picture on the first page, the first time I made a booboo.


Note, how bad the 375 gets when loaded towards its rated power but how good it is below 170ish watts. You gotta calculate the actual time it is in either state and can only then decide which way to go...


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sergiuhlihor avatar image
sergiuhlihor answered ·

Any updates on efficiency curves for individual models? I just bought a Victron Phoenix 24/500, which I choose assuming it will have good efficiencies in the 50-200W range, but I've measured it and it's nowhere near specs. Idle current is 0.4A (~11W) and measured efficiency at various points is 83-85% with a maximum of little below 87% at 170W output. Don't see anywhere the 90% indicated efficiency in specs... While model looks solid, if multiplus efficiencies are real, then it's actually way more efficient than what I have for almost all ranges, which is counterintuitive.

Would also be nice to see efficiency curves at various power factors also. And maybe a way on the app to see the actual efficiency of the inverter for last x kWh used from battery.

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johanndo avatar image
johanndo answered ·

you always will have an dc current overhead for the control board and relays on it, the more features a unit has, the more power it consumes.

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sergiuhlihor avatar image
sergiuhlihor answered ·

Are you saying that the 4W difference in idle from specs to real usage is the control board? If yes, this is honestly deceiving and should be included in the specs.

2 comments
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Alexandra avatar image Alexandra ♦ commented ·

@sergiuhlihor

Differences can also be due to meter tolerances.

Even Fluke say up to +/- 3% so the 4W easily falls into that amount.

If you look at specs for products even solar panels there is usually a stated 3% tolerance.... Due to measuring differences among other things.

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sergiuhlihor avatar image sergiuhlihor Alexandra ♦ commented ·
In the specs it's written 6.5W. Difference to 11 is about 70%, not 3-4%. The multimeter I use is correct and I see it as this affects my overall efficiency as much of my load is in the 30 to 100W range. I got an average measured efficiency of 79% for a full battery cycle. Would have hoped for at least 82-83.


A friend with a 24/3000 model observed also a delta of 4W on top of specs of 13W. Definitely the spec is wrong.


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