Lovelace card

The integration comes with its own Lovelace card, custom:battery-soc-card, and registers it with the frontend itself, so you do not need a resource entry under Settings → Dashboards → Resources. The card has two displays: a column (stored energy and time remaining) and a trajectory (a ring with six hours of history and a six hour projection).

display: column	display: trajectory

Configuration

type: custom:battery-soc-card
display: trajectory          # column | trajectory
soc_entity: sensor.speicher_soc_combined
power_entity: sensor.speicher_net_power
capacity_kwh: 12.8
reserve_percent: 10          # 0 = no reserve
invert_power: false          # true if your meter reports discharge as positive
runtime_entity: sensor.speicher_time_to_empty   # optional, wins over the linear estimate

Option	Meaning
display	column or trajectory.
soc_entity	The state of charge sensor. The only required option.
power_entity	Net battery power, positive while charging.
capacity_kwh	Usable capacity, used for stored energy and time remaining.
reserve_percent	Reserve the battery should not go below. 0 means no reserve.
invert_power	true if your meter reports discharge as positive.
runtime_entity	Optional time remaining sensor. Wins over the linear estimate.

Without a Recorder history for soc_entity (Recorder disabled, or retention shorter than six hours) the trajectory display only shows the projection. That is normal after a restart.

The card does not appear

The card only appears once the integration is set up as a device. It is registered with the frontend from async_setup_entry, so add a Battery SoC entry under Settings → Devices & Services first and then restart Home Assistant. Until then Lovelace reports Custom element doesn’t exist: battery-soc-card. If it still fails after the restart, reload the browser with Ctrl+Shift+R to drop the cached dashboard.