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