smarter-home.blog

Tag: energy monitoring

  • Generating a Beautiful Annual Solar PV Chart in Home Assistant

    This beautiful apexcharts chart gives me a clean annual view of solar PV performance month on month.

    chart showing annual solar pv generation month to month

    I show two things at once:

    1. Total kWh per month as orange columns.
    2. Average daily PV for that month as a dashed line.

    That pairing makes it easy to compare seasonal variation and spot how consistent generation is within each month.

    1) The time window

    I want a rolling 12-month view, aligned to the current year start, updating every 30 minutes.

    graph_span: 12month
update_interval: 30m
span:
  start: year
  offset: "-0d"

    2) Monthly totals as columns

    I read SolarEdge lifetime energy, convert Wh to kWh, then sum by month. I also enable statistics so ApexCharts aligns changes to month boundaries for accurate month on month totals.

    - entity: sensor.solaredge_lifetime_energy
  name: PV Last 12 Months
  color: var(--energy-solar-color)
  type: column
  float_precision: 0
  yaxis_id: first
  transform: return x / 1000;
  show:
    datalabels: true
  group_by:
    func: sum
    duration: 1month
    fill: zero
  statistics:
    type: change
    period: month
    align: end

    Why:

    • transform converts Wh to kWh.
    • group_by: sum gives a single monthly bar.
    • statistics: period: month ensures the change is aligned to the end of each month.

    3) Average daily PV as a dashed line

    I reuse the same entity and conversion, but average across the month, with statistics aligned by day. This produces a smooth “average day in this month” figure.

    - entity: sensor.solaredge_lifetime_energy
  name: PV Last 12 Months
  type: line
  stroke_dash: 3
  float_precision: 0
  color: "#3399FF"
  yaxis_id: second
  transform: return x / 1000;
  show:
    datalabels: true
  group_by:
    func: avg
    duration: 1month
    fill: zero
  statistics:
    type: change
    period: day
    align: end
  extend_to: false

    Why:

    • group_by: avg over a month produces the per-month daily average.
    • statistics: period: day uses daily changes to derive a meaningful daily rate.
    • stroke_dash: 3 makes the line read as a secondary metric.

    4) Dual y-axes for tidy scales

    Totals and averages sit on different ranges, so I bind columns to the left axis and the line to the right axis. Both are hidden to keep the design clean.

    yaxis:
  - id: first
    decimals: 2
    show: false
    min: 0
  - id: second
    opposite: true
    decimals: 0
    min: 0
    max: 80
    show: false

    5) Bar styling and stroke

    I keep columns compact with a subtle corner radius, and give lines a clear white stroke outline for contrast on dark themes.

    apex_config:
  plotOptions:
    bar:
      columnWidth: 28
      borderRadius: 1
  stroke:
    width: 2
    colors:
      - "#FFFFFF"

    6) Data labels with a custom formatter

    The line’s labels always show. Column labels only show for useful values, which keeps winter months uncluttered.

    apex_config:
  dataLabels:
    offsetY: -10
    style:
      fontSize: 10
    formatter: |
      EVAL: function(value, {seriesIndex, dataPointIndex, w }) {
        const roundedValue = Number(value).toFixed(0);
        if (seriesIndex === 1) {
          return roundedValue;
        }
        return roundedValue < 100 ? '' : roundedValue;
      }

    Why:

    • When seriesIndex === 1 (the dashed line), always show the rounded value.
    • For the column series, hide values below 100 kWh to avoid visual noise.

    7) Minimal legend and tooltip

    This is a glanceable tile, so I remove the legend and tooltips.

    apex_config:
  legend:
    show: false
  tooltip:
    enabled: false

    8) Month labels

    Three-letter month labels save space and remain readable.

    apex_config:
  xaxis:
    labels:
      hideOverlappingLabels: false
      rotate: 90
      show: true
      style:
        fontSize: 9
      format: MMM

    Full YAML

    type: custom:apexcharts-card
graph_span: 12month
update_interval: 30m
span:
  start: year
  offset: "-0d"
header:
  show: true
  title: Total Solar PV 2025 (kWh)
series:
  - entity: sensor.solaredge_lifetime_energy
    name: PV Last 12 Months
    color: var(--energy-solar-color)
    type: column
    float_precision: 0
    yaxis_id: first
    transform: return x / 1000;
    show:
      datalabels: true
    group_by:
      func: sum
      duration: 1month
      fill: zero
    statistics:
      type: change
      period: month
      align: end
  - entity: sensor.solaredge_lifetime_energy
    name: PV Last 12 Months
    type: line
    stroke_dash: 3
    float_precision: 0
    color: "#3399FF"
    yaxis_id: second
    transform: return x / 1000;
    show:
      datalabels: true
    group_by:
      func: avg
      duration: 1month
      fill: zero
    statistics:
      type: change
      period: day
      align: end
    extend_to: false
yaxis:
  - id: first
    decimals: 2
    show: false
    min: 0
  - id: second
    opposite: true
    decimals: 0
    min: 0
    max: 80
    show: false
apex_config:
  chart:
    height: 300px
  legend:
    show: false
  plotOptions:
    bar:
      columnWidth: 28
      borderRadius: 1
  stroke:
    width: 2
    colors:
      - "#FFFFFF"
  tooltip:
    enabled: false
  dataLabels:
    offsetY: -10
    style:
      fontSize: 10
    formatter: |
      EVAL: function(value, {seriesIndex, dataPointIndex, w }) {
        const roundedValue = Number(value).toFixed(0);
        if (seriesIndex === 1) {
          return roundedValue;
        }
        return roundedValue < 100 ? '' : roundedValue;      
      }      
  xaxis:
    labels:
      hideOverlappingLabels: false
      rotate: 90
      show: true
      style:
        fontSize: 9
      format: MMM

  • Monitoring Predbat Plan Generation Times in Home Assistant

    Predbat from springfall2008 is a fantastic custom integration for Home Assistant that intelligently manages solar battery charging and discharging based on predicted solar generation and energy tariffs. It’s especially helpful for optimising when to charge from the grid or discharge to avoid peak tariffs, and it’s saved me a decent amount on my energy bill.

    chart showing predbat on times

    But like any planning tool, Predbat needs time to generate its plan. Most of the time it does this quickly – but occasionally it can take a little longer. I wanted a way to visualise and track how long Predbat was taking to generate its plan each time it ran.

    Why track Predbat’s ON time?

    The provided switch.predbat_active entity goes into the on state when Predbat is generating a new plan. Once complete, it switches back to off. By measuring how long it remains ON, I can catch cases where Predbat is taking longer than expected.

    If it ever takes more than 5 minutes, I want to know – either through a notification or visually via my dashboard.

    Step 1: Creating the Sensor

    I used a trigger-based template sensor that calculates the duration in minutes that the switch.predbat_active was ON.

    Here’s the YAML for the sensor:

    - trigger:
    - platform: state
      entity_id: switch.predbat_active
      from: 'on'
      to: 'off'
  sensor:
    - name: Predbat Last ON Duration
      unique_id: predbat_last_on_duration
      state: >
        {{ (as_timestamp(now()) - as_timestamp(trigger.from_state.last_changed)) / 60 }}
      unit_of_measurement: "minutes"
      icon: mdi:timer

    This sensor will only update when the switch turns OFF. It records how many minutes it was ON – which is effectively how long Predbat took to generate its plan.

    Step 2: Visualising ON Durations in ApexCharts

    To make this information more useful, I plotted it using the excellent ApexCharts card for Home Assistant.

    Here’s the chart YAML I used:

    type: custom:apexcharts-card
graph_span: 24h
header:
  show: true
  title: Predbat ON Durations
  show_states: true
  colorize_states: true
series:
  - entity: sensor.predbat_last_on_duration
    type: column
apex_config:
  yaxis:
    min: 0
    max: 6
  annotations:
    yaxis:
      - "y": 5
        borderColor: "#FF0000"
        strokeDashArray: 1

    This renders a neat column chart of how long each plan generation took. The red annotation line at 5 minutes gives a clear visual cue if something is taking too long.

    Notifications and Automations

    Now that we have this entity, its a simple job to create a notification if the ON time is longer than my desired 5 minutes. Just use the new entity to trigger a notification to home assistant or your mobile device.