Versatile Load Manager (VLM)

Versatile Load Manager is an independent H24 controller for flexible electrical loads on Victron Venus OS installations. It uses local Victron energy data to schedule Shelly-controlled loads while respecting battery reserve, AC limits, runtime targets, allowed windows and hard safety conditions.

Typical loads include water heaters, pool pumps and other deferrable equipment. VLM runs locally on a Cerbo GX or remotely on a Raspberry Pi; Node-RED is not required.

VLM is an independent community project. It is not an official Victron Energy or Shelly product and is not affiliated with or endorsed by either company.

Safety first

A fresh installation cannot command a relay or change the DVCC charge-current limit. Three explicit permissions protect commissioning:

• dry_run: false permits writes globally;
• control_enabled: true permits Shelly commands;
• battery.control_enabled: true separately permits DVCC writes.

Keep all three locks closed during the first observation period. VLM also blocks starts on invalid telemetry or grid loss, enforces AC headroom, supervises relay power and preserves relay ownership across restarts.

Start here

1. Read the Cerbo GX getting-started guide.
2. Install the offline Venus package from a project release.
3. Configure the real installation while keeping every control lock closed.
4. Run /data/vlm check.
5. Observe decisions continuously before enabling one load at a time.

The installer creates /data/versatile-load-manager, installs a native runit service and leaves it stopped. It never overwrites an existing config.yaml.

Main capabilities

• automatic discovery of Victron Modbus services;
• priority, runtime, seasonal target and scheduling rules for multiple loads;
• solar-surplus allocation with AC headroom and anti-cycling protection;
• required-runtime catch-up during off-peak hours;
• solar-first Pylontech balancing through guarded DVCC control;
• persistent runtime, lockout, relay-ownership and balancing state;
• Tempo and PV-forecast inputs without making network access part of the safety-critical control loop;
• watchdog recovery and supervised automatic restart on Venus OS.

Documentation

• Getting started on Cerbo GX
• Understanding VLM decisions
• Architecture and safety model
• Configuration reference
• Detailed behavior reference
• Troubleshooting and log collection
• Tempo and solar-forecast design
• Fronius zero-export fallback

Technical names

The project, Python package, installation directory, service and release archives consistently use versatile-load-manager (or versatile_load_manager where Python requires underscores). The short administrative command remains /data/vlm.

License

Versatile Load Manager is licensed under the Mozilla Public License 2.0 (MPL-2.0).

Copyright (c) 2026 Bertrand Feuerstein.

Modifications to MPL-covered VLM files that are distributed must remain available under the MPL 2.0. Separate files may be combined with VLM under other licenses as permitted by the MPL. See NOTICE for attribution.

Project status

VLM is under active development and should remain in read-only observation mode until its decisions have been checked against the real installation. Review the safety model and configuration reference before enabling commands.