Feature: Support for multi-tower FENECON systems (up to 3 battery towers)

[alpenfun]

🚀 Feature: Support for multi-tower FENECON systems (up to 3 battery towers)

Description

The current implementation of FEMS Diagnostics is primarily designed and validated for systems with a single battery tower.

However, FENECON Home systems support configurations with multiple battery towers (up to 3 towers with multiple modules each).

To improve compatibility and scalability, support for multi-tower systems should be added.

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Background

According to FENECON system specifications, configurations such as:

• 1 tower (current standard setup)
• 2 towers
• 3 towers (e.g. up to ~66 kWh total capacity)

are supported and commonly used.

This requires proper handling of:

• multiple tower indices
• per-tower diagnostics
• aggregated system values

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Scope of this feature

1. Sensor layer

• Generalize tower handling (tower0 → towerX)
• Dynamically create sensors per tower
• Avoid hardcoded tower references
• Ensure consistent naming scheme

2. Diagnostics

• Provide:

  • per-tower diagnostics (voltage, temperature, alarms, warnings)
  • aggregated system diagnostics (min/max across all towers)

• Avoid duplication between system-level and tower-level values

3. Dashboard

• Extend dashboard to:

  • display multiple towers cleanly
  • optionally group towers in sections or tabs

• Keep default dashboard simple for single-tower users

4. Configuration

• Introduce optional configuration:

  • number of towers (auto-detect if possible)

• Maintain backward compatibility

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Design considerations

• Must remain fully backward compatible for single-tower systems
• Avoid UI clutter for small systems
• Keep performance impact minimal
• Prefer dynamic sensor creation over static definitions

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Proposed implementation approach

1. Refactor sensor definitions to support tower_index

2. Introduce dynamic sensor builders for towers

3. Implement aggregation layer for system-wide values

4. Extend dashboard structure for multi-tower setups

5. Test with:

   • 1 tower
   • 2 towers
   • 3 towers (target scenario)

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Goal

Enable FEMS Diagnostics to support all standard FENECON Home configurations, including multi-tower systems, while maintaining a clean and user-friendly experience.

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Status

📌 Planned / Not yet implemented

[Lamarqe]

Hello @alpenfun,

I noticed your integration and got curious. I really appreciate your focus thoughts around different voltage levels in the different battery cells.

I tried to replicate the example dashboard using the generic ha_openems integration and did so within one evening of reverse engineering the config you implemented.

Essentially, it requires two styles of template sensors on top of the default configuration:

1. battery_cell_voltage_spread:
   {{ states("sensor.fems12345_battery0_maxcellvoltage") |float - states("sensor.fems12345_battery0_mincellvoltage") | float }}
2. towerX_moduleY_cell_voltage_spread: (eg for tower0, module 000):
   {% set my_values = device_id("fems12345 battery0") | device_entities | select("match", ".*tower0module0cell...voltage") | expand | map(attribute="state") | list %} {{ my_values | max | float - my_values | min | float}}

If you are interested, I could provide a small extra config option in ha_openems. If enabled, these additional template diagnostics sensors would be automatically created for every battery / tower / module which is part of the connected system.

As this is fully generic, multi-tower and even multi battery systems will be implicitly supported.
Let me know if you are interested.

[Lamarqe]

Attached the respective dashboard config and a screenshot of the dashboard in my system. (My FEMS has only four modules)