FoxESS Community - Owners & Installers Forum

I guess the very first thing all of us on Octopus did was compare the export/grid consumption figures for last month to see if they matched.... hmmm..... export is near enough right ( 0.21 kwh discrepancy) but grid import Fox is 3 kwh lower.

I wonder where the difference is ? Is there a mouse slowly electrocuting itself somewhere between the meter and the inverter ?

Overall though it's a big thumbs up for app 2.0 - the analytics page tells me all the things I wanted to know - how many kwh am I generating, using, buying and selling.

The inverter uses a CT clamp to measure the power usage, and a CT clamp has between a 1 and 5% accuracy, it becomes less accurate on smaller loads.

Your smart meter also effectively takes into account power factor as it is sampling power values very quickly something a CT clamp can't do.

All in all you'll never get a precise match to your smart meter, but over time you'll learn roughly what the differences are between them - it sounds like export is close (likely because of the higher power) and import is less so - but if you look at the % difference as long as your house usage stays consistent you should get the % accuracy for your installation - mine is consistently between 1 & 2% below my smart meter reading.

FYI - you can improve the accuracy by replacing the CT clamp with a meter, they won't be as accurate as the smart meter (because of power factor) but much closer than a CT clamp.