Graph based on last values of a sensor

Hi folks,
I have a simple solar setup in my garden with an ESP8266 monitoring voltage of a lead acid battery and reporting it to Home Assistant. The problem is that the battery voltage fluctuates greatly due to the solar controller using PWM to change the battery. So I can read 12.6v followed by 13.8v with the 1st reading being the battery float voltage and the 2nd one being the battery charging voltage.

I am trying to graph the battery voltage changes day-to-day with Mini Graph Card (code below). This code works poorly because it takes the minimal value of each day which does not bring much insight.
What I am trying to implement instead is to have a graph that would capture my battery voltage as of the specific time/period in the day, say, between 2am and 2.10am, when there is no charging going on, but I struggle to implement it.

Does anyone have any suggestions?

type: 'custom:mini-graph-card'
name: Solar Battery
decimals: 1
aggregate_func: min
group_by: date
hours_to_show: 168
height: 70
line_width: 5
font_size: 75
font_size_header: 14
bar_spacing: 2
  state: true
  indicator: true
  icon: true
  name: true
  graph: bar
  fill: true
  legend: false
  - entity: sensor.solar_battery_voltage
    color: '#d6b65e'
    show_state: true

You could create a triggered template sensor that only measures the battery voltage between 2am and 2:10am.

  - trigger:
      - platform: template
        value_template: "{{ now().hours == 2 and ( 0 <= now().minutes <= 10 ) }}"
      - name: "Battery Voltage 2 AM"
        state: "{{ states('sensor.solar_battery_voltage') }}"
        unit_of_measurement: "V"