Energy Dashboard: How the summary is done?

Configuration
1

I have a custom arduino wifi sensor sending Energy consumption data every minute (fe: 0.012kWh = 12 blinks in my energymeter). Sensor is working well and it’s sending accurate data every minute.

My config is as follows:

sensor:
  - platform: mqtt
    unit_of_measurement: 'kWh'
    name: 'Sahko_Mittari_kWh'
    state_topic: "sahkokaappiLaite/ldr/state"
    state_class: "total_increasing"
    device_class: "energy"

Problem:
My Energy Dashboard is showing too low readings. Only 0.42kWh/hour when my sensor is sending about 0.010 kWh/min and my houses average consumption is about 1kWh/hour, still all of the records are below 1kWh/h:

image
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Could it be rounding issue? Is energy dashboard doing some rounding? I cannot believe that my sensor would miss so many sends…