Frient frient Electricity Meter Interface / Develco ZHEMI101

I have 3 Frient Electricity Meter Interface / Develco ZHEMI101 setup on 3 different export meters all monitoring different solar arrays I have and they all communicate with HA using Zigbee2mqtt.
I have found that with them setup as they should be at 1000 pulses per kWh, after a few days the meter reading in HA differs slightly to the corresponding one on the actual export meter.
I have re synchronized them several times but always end up being higher than the actual meter display after a few days.
To try and work around this problem at the moment I have changed the setting in Zigbee2mqtt to 1005 pulses per kWh and will check after a few days again to see if there is a difference.
Has anyone else who uses these type of energy monitors had a similar experience?