What's with MPP Solar unit having very low Power Factor?

powerhey

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Feb 28, 2020
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Hi there

So I've got an MPP Solar PIP-5048GK 5KW 48VDC SOLAR INVERTER and 4x 12v 150ahr lifepo4's (in series.)

When the MPP Solar unit is charging the batteries using mains power, at ~550 watts charging, a seperate kilowatt-hour meter says a power factor of ~0.5.
I've got the charge voltage and float voltage set to 53v (for ~80% charge).
I've left it charging and after ~15 hours it seems to get ever closer to finish charging but never gets there.
After ~15 hours, it's still pumping about 25 watts into the batteries (measured with 4A DC clamp meter at several different points.)
At this point, the inverter's power factor is only 0.12, and when I disconnect the batteries so that the inverter is not doing any active work, it pulls about 70 watts and has a power factor of only 0.08!

Why does this unit have such a low power factor?
Will this have any knock on effects? Eg. hopefully the power bill will charge for 70 watts instead of 800 watts!

I know little about this, but I thought it would be a fair assumption that modern equipment that doesn't have big heavy transformers in them would have a fairly high power factor.

I tested the meter that I used to measure the power factor with a heatgun to make sure it was a fair reading. At ~150 watts it was 0.9 something, and at ~2000 watts it was 1.00, so it looks like the meter is fine.

Cheers
 

daromer

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The MPP have an idle usage of around 70-80w per phase no matter what you run on it. Its normal on such electronics to be fair and especially to the cost you pay for those devices. They aint cheap to run, especially not when running small loads.

It can also be different to meassure. You cant compare meassuring a resistive load comparing to an inductive. How you pay for va vs watt i cant tell. depends on how your house hold meter is made.

Note that resistive load is 1.0 and nothing else. But if you run it through an inverter it changes. The older MPP is only PF 0.8 on resistive load meanwhile the new are stated to come close to 1.0.
 

powerhey

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If I were to power it from a 700 w continuous "pure sinewave" generator instead of from the mains, would the generator be able to power it if it were pulling say 550 watt with a power factor of 0.5?
 

OffGridInTheCity

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If I were to power it from a 700 w continuous "pure sinewave" generator instead of from the mains, would the generator be able to power it if it were pulling say 550 watt with a power factor of 0.5
I'm not up on "Power Factor" thinking - but my generator often deliver less than you'd think 'smoothly'. 700w -> 550w is fairly close, so I'd test it and see before concluding it will work :)
 

daromer

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And every time you convert you loose energy.
 
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