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Changelog

All notable changes to this project will be documented in this file.

The format is based on Keep a Changelog, and this project adheres to Semantic Versioning.

[2.1.7] - 2025-09-13

This update is a maintenance release to improve Code Quality, CI and update the dependencies. There are no changes or new features.

Added

  • Added version to flixopt

Development

  • ruff format the whole Codebase
  • Added renovate config
  • Added pre-commit
  • lint and format in CI
  • improved CI
  • Updated Dependencies
  • Updated Issue Templates

[2.1.6] - 2025-09-02

Changed

  • Sink, Source and SourceAndSink now accept multiple flows as inputs and outputs instead of just one. This enables to model more use cases using these classes. [#291 by @FBumann]
  • Further, both Sink and Source now have a prevent_simultaneous_flow_rates argument to prevent simultaneous flow rates of more than one of their Flows. [#291 by @FBumann]

Added

  • Added FlowSystem.start_network_app() and FlowSystem.stop_network_app() to easily visualize the network structure of a flow system in an interactive dash web app. This is still experimental and might change in the future. [#293 by @FBumann]

Deprecated

  • For the classes Sink, Source and SourceAndSink: .sink, .source and .prevent_simultaneous_sink_and_source are deprecated in favor of the new arguments inputs, outputs and prevent_simultaneous_flow_rates. [#291 by @FBumann]

Fixed

  • Fixed testing issue with new linopy version 0.5.6 [#296 by @FBumann]

[2.1.5] - 2025-07-08

Fixed

  • Fixed Docs deployment

[2.1.4] - 2025-07-08

Fixed

  • Fixing release notes of 2.1.3, as well as documentation build.

[2.1.3] - 2025-07-08

Fixed

  • Using Effect.maximum_operation_per_hour raised an error, needing an extra timestep. This has been fixed thanks to @PRse4.

[2.1.2] - 2025-06-14

Fixed

  • Storage losses per hour where not calculated correctly, as mentioned by @brokenwings01. This might have lead to issues with modeling large losses and long timesteps.
  • Old implementation: \(c(\text{t}_{i}) \cdot (1-\dot{\text{c}}_\text{rel,loss}(\text{t}_i)) \cdot \Delta \text{t}_{i}\)
  • Correct implementation: \(c(\text{t}_{i}) \cdot (1-\dot{\text{c}}_\text{rel,loss}(\text{t}_i)) ^{\Delta \text{t}_{i}}\)

Known issues

  • Just to mention: Plotly >= 6 may raise errors if "nbformat" is not installed. We pinned plotly to <6, but this may be fixed in the future.

[2.1.1] - 2025-05-08

Fixed

  • Fixed bug in the _ElementResults.constraints not returning the constraints but rather the variables

Changed

  • Improved docstring and tests

[2.1.0] - 2025-04-11

Added

  • Python 3.13 support added
  • Logger warning if relative_minimum is used without on_off_parameters in Flow
  • Greatly improved internal testing infrastructure by leveraging linopy's testing framework

Fixed

  • Fixed the lower bound of flow_rate when using optional investments without OnOffParameters
  • Fixed bug that prevented divest effects from working
  • Added lower bounds of 0 to two unbounded vars (numerical improvement)

Changed

  • BREAKING: Restructured the modeling of the On/Off state of Flows or Components
  • Variable renaming: ...|consecutive_on_hours → ...|ConsecutiveOn|hours
  • Variable renaming: ...|consecutive_off_hours → ...|ConsecutiveOff|hours
  • Constraint renaming: ...|consecutive_on_hours_con1 → ...|ConsecutiveOn|con1
  • Similar pattern for all consecutive on/off constraints

[2.0.1] - 2025-04-10

Added

  • Logger warning if relative_minimum is used without on_off_parameters in Flow

Fixed

  • Replace "|" with "__" in filenames when saving figures (Windows compatibility)
  • Fixed bug that prevented the load factor from working without InvestmentParameters

[2.0.0] - 2025-03-29

Changed

  • BREAKING: Complete migration from Pyomo to Linopy optimization framework
  • BREAKING: Redesigned data handling to rely on xarray.Dataset throughout the package
  • BREAKING: Framework renamed from flixOpt to flixopt (import flixopt as fx)
  • BREAKING: Results handling completely redesigned with new CalculationResults class

Added

  • Full model serialization support - save and restore unsolved Models
  • Enhanced model documentation with YAML export containing human-readable mathematical formulations
  • Extend flixopt models with native linopy language support
  • Full Model Export/Import capabilities via linopy.Model
  • Unified solution exploration through Calculation.results attribute
  • Compression support for result files
  • to_netcdf/from_netcdf methods for FlowSystem and core components
  • xarray integration for TimeSeries with improved datatypes support
  • Google Style Docstrings throughout the codebase

Fixed

  • Improved infeasible model detection and reporting
  • Enhanced time series management and serialization
  • Reduced file size through improved compression

Removed

  • BREAKING: Pyomo dependency (replaced by linopy)
  • Period concepts in time management (simplified to timesteps)