Add iometer integration documentation (#36860)

Co-authored-by: MaestroOnICe <justuskrebs@campus.tu-berlin.de>

source/_integrations/iometer.markdown

@@ -0,0 +1,62 @@
+---
+title: IOmeter
+description: Instructions on how to integrate IOmeter within Home Assistant.
+ha_release: 2025.2
+ha_category:
+  - Sensor
+  - Energy
+ha_codeowners:
+  - '@MaestroOnICe'
+  - '@iometer-gmbh'
+ha_quality_scale: bronze
+ha_domain: iometer
+ha_integration_type: integration
+ha_iot_class: Local Polling
+ha_config_flow: true
+ha_zeroconf: true
+---
+
+The **IOmeter** {% term integration %} fetches data from your [IOmeter](https://iometer.de/produkt/) device, by using the local HTTP API.
+
+IOmeter is a German company that provides the IOmeter device for reading electricity meters.
+
+{% important %}
+In order for the IOmeter to be used by Home Assistant, the Core/Bridge firmware version should be at least 62/69.
+{% endimportant %}
+
+{% include integrations/config_flow.md %}
+
+### Configuration parameters
+
+{% configuration_basic %}
+IP address:
+  description: The IP address of your IOmeter.
+{% endconfiguration_basic %}
+
+## Data updates
+
+The integration will update its sensors by polling the IOmeter Bridge every ten seconds for new values. We recommend using USB-C power for the IOmeter Core instead of batteries.
+
+## Available sensors
+
+The following sensors are supported:
+
+- Power (W): Active power
+- Total energy usage (kWh): How much energy the meter used
+- Total energy returned (kWh): How much energy the meter returned to the grid
+- Meter number: Electricity meter number
+- Pin status: Electricity meter pin status
+- Core battery level: Battery level of the IOmeter Core in percent
+- Core power status: Battery or USB-C power for the IOmeter Core
+- Signal strength WiFi: WiFi connection strength of the Bridge
+- Signal strength Core/Bridge: Sub-GHz connection strength between Core and Bridge
+
+## Troubleshooting
+
+There are no commonly known issues with this integration.
+
+## Remove integration
+
+This integration follows standard integration removal. No extra steps are required.
+
+{% include integrations/remove_device_service.md %}