Home Assistant Sensors¶

miniEMS registers up to 34 sensors in Home Assistant via the bundled custom integration. All entity IDs use the prefix sensor.miniems_. The integration polls /api/status every 30 s and registers all entities under the miniEMS device with long-term statistics support.

Multilingual sensor names (from v1.6.0): Sensor display names in the Home Assistant UI automatically follow the language configured in HA. Supported languages: English and German. Entity IDs (e.g. sensor.miniems_today_grid_cost_eur) remain unchanged.

Scope — addon-native only. Live power readings (PV, load, grid, battery power, SoC) and the electricity price are not duplicated here. Those sensors already exist in HA from your inverter integration (e.g. Deye) and your price integration (e.g. Tibber, Octopus Energy). miniEMS reads those entities internally but does not re-publish them.

Scenario 2 sensors (inverter efficiency, energy-balance grid charge, ROI) are only available when the corresponding inverter entities have been configured (today_production_entity, today_losses_entity, battery_discharge_entity, etc.).

Operating Mode¶

Battery State¶

Computed from the current SoC and the configured capacity / SoC limits.

free_to_charge = (max_soc − soc) / 100 × capacity_kwh
useable        = (soc − min_soc)  / 100 × capacity_kwh

When battery_capacity_entity is configured, the capacity is read directly from the inverter (e.g. 25.8 kWh). Otherwise the config value battery_capacity_kwh is used.

Today's Energy¶

Accumulate from midnight; reset daily. state_class: total_increasing.

Today's Cost & Savings¶

For a full explanation of every sensor, including a worked example: Costs & Savings.

What do the cost sensors mean in comparison?¶

The different cost sensors enable direct scenario comparison:

Price Tier Usage¶

Load (kWh) split by electricity price tier. Tier boundaries are set by cheap_rate_threshold_eur and medium_rate_threshold_eur in Settings.

All six sensors have state_class: total_increasing and are restored from the database on restart.

Weekly / Monthly / Yearly Totals¶

Aggregated from the daily_stats database table.

Predictions¶

Scenario 2: Grid Charging — Efficiency & ROI¶

These sensors are optional and only available when the following entities are set in the configuration: today_production_entity, today_losses_entity, battery_discharge_entity, battery_charge_entity.

What do these sensors mean?¶

miniems_today_efficiency_pct — Inverter Efficiency¶

The inverter converts stored energy into usable electricity — with losses. Efficiency describes how much of the produced PV energy actually reaches the household.

η = (PV production today − losses today) / PV production today × 100

Example: PV production 32.5 kWh, losses 2.6 kWh → η = 92.0 %

Typical values: 88–95 %. The higher, the more efficiently the inverter is operating.

miniems_today_grid_charge_kwh_bilanz — Grid Charge (Energy Balance)¶

Shows how much energy actually flowed from the grid into the battery today. The calculation uses the inverter's energy-balance formula — more precise than approximating from instantaneous power readings:

grid_charge_energy = grid_import_today − load_consumption_today + battery_discharge_today

Why not just use the grid import? Part of the grid import covers household consumption directly. The formula subtracts this portion, leaving only the true battery-charging share.

Plausibility check: The value must be ≥ 0 and ≤ total battery charge today.

miniems_today_grid_charge_roi_eur — Grid Charging ROI¶

The most important sensor for evaluating the grid-charging strategy:

profit = (grid_charge_kWh × efficiency × avg_discharge_tariff) − grid_charge_cost

• Positive value → Grid charging paid off today ✅
• Negative value → Grid charging cost more than the benefit ❌
• No value shown → Discharge tariff (avg_discharge_tariff_eur_kwh) not configured

Configuration required: avg_discharge_tariff_eur_kwh must be set to the average tariff at which the battery discharges (e.g. 0.394366 for pure evening peak, or 0.369376 for mixed evening/night discharge).

Concrete example:

Grid charge: 5.5 kWh, η: 92 %, discharge tariff: 0.394 €/kWh, charge cost: 1.51 €
Usable energy: 5.5 × 0.92 = 5.06 kWh
Saving: 5.06 × 0.394 = 1.99 €
ROI = 1.99 − 1.51 = +0.48 € ✅

Using Sensors in HA¶

Example Lovelace card¶

type: entities
title: miniEMS
entities:
  - sensor.miniems_mode
  - sensor.miniems_today_grid_cost_eur
  - sensor.miniems_today_pv_savings_eur
  - sensor.miniems_today_cost_without_grid_charge
  - sensor.miniems_battery_kwh_freetochange
  - sensor.miniems_battery_kwh_useable
  - sensor.miniems_predicted_load_kwh

Example Automation¶

alias: Notify when cheap rate starts
trigger:
  - platform: state
    entity_id: sensor.miniems_mode
    to: "Grid Charging (Cheap Rate)"
action:
  - service: notify.mobile_app_your_phone
    data:
      message: "miniEMS: Charging from cheap grid rate."