Turn power meter readings of EDL21 into instantaneous consumption

Hi all,

I have a power meter (vendor: ISKRA MT681) that I read out with IR interface from Hichi.

It works fine after the January 2022 update of HA (see screenshot).
I get a reading (via template code I found on Github) showing me instantaneous net consumption (“Nettobezug”) from grid under consideration of my photovoltaic production - this is what I need to charge my vehicle while I have more production than consumption.

However, I would also like to see my instantaneous production (negative active energy) and consumption (positive active energy). I tried with statistics and also riemann integration but to no avail (failures in parsing configuration.yaml).

I only get absolute readings (see screenshot) - could someone point me into the right direction of how to get the present consumption/production from my EDL21 sensors?
It would probably have to be calculated by (reading at time t2 minus reading at time t1)/(t2 minus t1).
It should be ok if the sensor value is aggregated over the last e.g. (t2 minus t1) = 10 to 30 seconds.

# Configure a default setup of Home Assistant (frontend, api, etc)
default_config:

# Specific 
sensor:
  - platform: edl21
    name: Stromzaehler
    serial_port: /dev/ttyUSB0

#sensor:
#  - platform: integration
#    source: sensor.stromzaehler_positive_active_energy_in_tariff_t1
#    name: Strombezug_180 
#    unit_prefix: k
#    round: 2 
    
    
template:
  - sensor:
      - name: Strombezug
        state: >
           {% set pwrin = states('sensor.stromzaehler_positive_active_energy_in_tariff_t1') | float %}
           {{ pwrin / 1000 | round(3) }} 
        unit_of_measurement: kWh
        state_class: total_increasing
        device_class: energy
#zusätzlich 300122        
      - name: Einspeisung
        state: >
           {% set pwrin = states('sensor.stromzaehler_negative_active_energy_in_tariff_t1') | float %}
           {{ pwrin / 1000 | round(3) }}
        unit_of_measurement: kWh
        state_class: total_increasing
        device_class: energy
        
      - name: Nettobezug
        state: >
           {% set pwrin = states('sensor.stromzaehler_sum_active_instantaneous_power') | float %}
           {{ pwrin / 1000 | round(3) }}
        unit_of_measurement: kWh
        state_class: total_increasing
        device_class: energy
        
#Experimental
#sensor:
#  - platform: integration
#    name: Strombezugintegriert
#    source: sensor.Strombezug
#    unit_time: min 
#    method: left

# Text to speech
tts:
  - platform: google_translate

group: !include groups.yaml
automation: !include automations.yaml
script: !include scripts.yaml
scene: !include scenes.yaml

There is a predefined sensor for this called name: sensor.sum_active_instantaneous_power
The only issue with that is that it only refreshes about every 60 Seconds