UK Power factors

[MikeSp]

Hello,
I am not a professional, but I have some knowledge of electrical installation and also of theory. Sorry in advance for a long post!

At work, we've augmented our 15-20 y/o mechanical meters with electronic meters with HH (half hour) readings (fed using CT clamps), which are sent using RS485 to a consolidator and stored for posterity. We can not reconcile the KWH values on several of the meters by considerable margins. Old and new meters are MID compliant, and from the same (well established) company.

We are being told that we have a power factor problem, and also that the solar panel inverters are sending out harmonics which are causing the problems.

I am trying to identify whether or not this is true, and if so, will then look to resolve it. However, the PF values are so wild, that I would like to understand more, and where to start investigating. Of note, is that our power provider charges us about £12 a month for power factor correction, on a bill of about £9000 per month (yes £9k!), so we do not think we have a notably "poor" PF.

My first question is "are PFs of -0.44, 0.34 etc. reasonable for a normal office (e.g. computers, kettles and air conditioning)".
My second is "Can solar panel harmonics affect metering so vastly (inverters are 12Kw - 80Kw Solis, so not cheap ebay purchases".
My third is "Where would I go from here!".

Really appreciate any help, thank you,

Mike

I have all the data for months, and can analyse it reasonably readily, but to give you an idea of my question, below are two extracts in CSV format for 01:30 (night - no generation) and 15:00 (day - generation)

Data is meter ID, KW,KVA and KVAR (for the HH), and individual and net PF (instantaneous, I presume).
I have put it in this post as text, so it could possibly be saved to a CSV and viewed in Excel

Id,Date,Tot. KW,Tot. KVA,L3 KVAR,L1 PF,L2 PF,L3 PF,Tot. PF
41237,02 07 2025 01:30,-0.62,1.43,-0.27,-0.44,-0.51,-0.21,-0.44
41238,02 07 2025 01:30,-0.22,0.40,-0.07,0.03,-0.74,-0.85,-0.56
41239,02 07 2025 01:30,0.06,0.11,0.00,-0.46,0.49,0.00,0.54
41240,02 07 2025 01:30,0.06,0.07,0.00,0.50,0.59,0.00,0.94
41242,02 07 2025 01:30,0.08,0.10,0.02,0.86,0.89,0.89,0.86
41243,02 07 2025 01:30,17.92,22.30,-5.15,0.75,0.92,0.66,0.80
41246,02 07 2025 01:30,1.04,1.36,-0.34,0.66,0.73,0.79,0.77
41247,02 07 2025 01:30,3.39,2.94,-0.34,0.66,0.78,0.49,0.84
41248,02 07 2025 01:30,-3.77,3.92,4.29,0.70,-0.96,-0.63,-0.96
41249,02 07 2025 01:30,0.41,0.50,-0.03,0.80,0.58,0.82,0.83
41250,02 07 2025 01:30,1.81,2.11,-0.06,0.73,0.83,0.94,0.86
41542,02 07 2025 01:30,1.26,1.31,0.00,0.91,0.94,0.00,0.96
41543,02 07 2025 01:30,2.17,3.49,-1.80,0.46,0.79,0.57,0.62
41544,02 07 2025 01:30,0.52,1.18,-0.39,0.26,0.18,0.64,0.44
41545,02 07 2025 01:30,2.20,2.75,-0.72,0.76,0.90,0.66,0.80
41546,02 07 2025 01:30,0.49,1.05,-0.36,0.61,0.21,0.46,0.46
41547,02 07 2025 01:30,0.61,1.79,-0.48,0.33,0.48,0.12,0.34
41548,02 07 2025 01:30,-3.48,3.52,0.59,-0.70,-0.90,-0.79,-0.99
41551,02 07 2025 01:30,0.16,1.37,-0.15,-0.10,0.61,-0.63,0.12
41552,02 07 2025 01:30,2.24,2.79,0.42,0.42,0.74,0.79,0.80
41553,02 07 2025 01:30,0.00,0.38,0.10,0.86,0.01,-0.84,0.01

41237,02 07 2025 15:00,0.19,3.27,-0.44,-0.01,0.07,0.23,0.06
41238,02 07 2025 15:00,-0.23,0.41,-0.07,0.04,-0.75,-0.86,-0.56
41239,02 07 2025 15:00,-0.05,0.10,0.02,-0.39,0.55,-1.00,-0.56
41240,02 07 2025 15:00,0.06,0.08,0.00,0.65,0.36,0.00,0.79
41242,02 07 2025 15:00,4.41,8.55,-2.42,0.52,0.51,0.52,0.52
41243,02 07 2025 15:00,-54.13,55.18,-4.62,-0.91,-0.98,-0.96,-0.98
41246,02 07 2025 15:00,2.79,2.83,-0.24,0.65,1.00,0.46,0.98
41247,02 07 2025 15:00,3.77,4.12,-0.12,0.85,0.88,0.96,0.93
41248,02 07 2025 15:00,23.28,23.28,3.67,-0.96,0.99,0.97,1.00
41249,02 07 2025 15:00,0.49,0.59,-0.05,0.71,0.58,0.76,0.83
41250,02 07 2025 15:00,1.74,2.07,-0.06,0.70,0.82,0.94,0.84
41542,02 07 2025 15:00,1.10,1.21,0.00,0.90,0.87,0.00,0.91
41543,02 07 2025 15:00,4.09,5.05,-1.91,0.77,0.92,0.70,0.81
41544,02 07 2025 15:00,0.99,1.51,-0.41,0.52,0.45,0.64,0.65
41545,02 07 2025 15:00,2.75,3.37,-0.86,0.78,0.77,0.72,0.82
41546,02 07 2025 15:00,3.49,3.88,-0.54,0.89,0.90,0.90,0.90
41547,02 07 2025 15:00,14.97,15.25,-0.97,0.87,0.98,0.99,0.98
41548,02 07 2025 15:00,84.29,84.68,-2.99,0.99,0.99,0.99,1.00
41551,02 07 2025 15:00,8.93,13.01,-3.36,0.58,0.80,0.22,0.69
41552,02 07 2025 15:00,3.17,3.67,0.76,0.36,0.78,0.75,0.86
41553,02 07 2025 15:00,67.80,68.01,27.86,0.48,0.99,0.55,1.00

 

[plugsandsparks]

I would first check that all CT connected meters have been set up correctly, i.e. CT for L1 is actually on L1 etc, they should line up with voltage line. Check all CTs are of the correct value, i.e. 400/5 etc and that the meters have the correct CT configurations to match the CTs. Most issues will be resolved here.
very low PF and bouncing from Cap to Ind can happen with very small loads like you describe.
I would worry about the harmonic factor last, as , in theory, all this stuff should be tolerant of expected harmonics from the devices you mention.

 

[MikeSp]

Thank you for that information - I thought I'd replied this morning, but apparently not!
I will get an independant electrician to check the CTs are correctly installed and of the appropriate rating.

Some boards are protected by 200A or 400A fuses due to historical loads, but now rarely exceed 20A peak, so may benefit from 'smaller' CTs.

I have thought of another thing. If the grid 'sees' the load as PF 0.98 (this hs been calculated by someone who understands the reactive charge on the bill) is it likely that many of our meters are showing a much lower figure. Just curious as to how this could be the case.


Thanks

 

[plugsandsparks]

Different meters can measure different things, e.g. They will all measure KW as generally that is what you pay for, many meters will measure KVA and KVAr also. They are all capable of dealing with PF, as mentioned, most of these issue get solved as i mentioned above. 0.98 is nothing to worry about.