Power Splitter

This tool retrieves power consumption data from an InfluxDB database. It then divides up the total power imported from the grid among various users, such as a heat pump, a wallbox, and the household.

This enables SOLECTRUS to accurately calculate the electricity usage and costs for each distinct consumer. This is especially useful in settings where multiple devices or systems are drawing power.

See CALCULATION.md for how the split is calculated.

Requirements

• InfluxDB 2 database with a bucket filled with values for:
  • Grid import power
  • House power
  • Heatpump/Wallbox/Custom power
• Linux machine with Docker installed

Getting started

1. Make sure that your InfluxDB2 database is ready (not subject of this README)

2. Prepare an .env file (see .env.example)

3. Run the Docker container on your Linux box:

   docker compose up

The Docker image supports multiple platforms: linux/amd64, linux/arm64

To force a data rebuild, you can send USR1 signal to the container:

docker compose kill --signal USR1 power-splitter

Batteries charged from the grid

A home battery can be charged from the grid, so the energy taken out of it later is not necessarily PV. To tell the two apart, the Power Splitter needs to see both directions of the battery:

Variable	Description
INFLUX_SENSOR_BATTERY_CHARGING_POWER	Sensor for the power flowing into the battery, as measurement:field
INFLUX_SENSOR_BATTERY_DISCHARGING_POWER	Sensor for the power flowing out of it. Without it there is nothing to tell the two apart by, and what leaves the battery counts as PV

The sensor names and their format are the same as in SOLECTRUS, so the lines can be copied over from its .env.

Once both sensors are there, grid energy stored in the battery is attributed to the consumers taking it out again. There is no switch for it.

Important

The attribution needs a SOLECTRUS version that knows about the battery as a second source of grid electricity. Older versions expect the grid shares of all consumers to add up to the power imported from the grid, and scale them until they do. That not only undoes the attribution, it also drags down battery_charging_power_grid - a value that was correct before.

This version calculates the grid shares differently than the one before it, with or without the battery sensors. Existing data is only overwritten where the new calculation writes something, so old and new numbers would otherwise sit side by side.

With both battery sensors set, this is noticed on start: records that do not carry the battery ledger were calculated by an older version, so they are deleted and rebuilt from scratch. The daily summaries are reset along with them, as long as the DB_* variables are set. Nothing needs to be done by hand.

Without them there is no such marker, so after updating:

1. Force a rebuild (see above)
2. Reset the daily summaries in SOLECTRUS

See CALCULATION.md for what these variables do to the calculation, which fields are written, and where the limits are.

Development

For development you need a recent Ruby setup. On a Mac, I recommend rbenv.

Run the app

bundle exec app.rb

Run tests

bundle exec rspec

Run linter

bundle exec rubocop

License

Copyright (c) 2024-2026 Georg Ledermann georg@ledermann.dev