Changelog¶

This project adheres to Semantic Versioning. Formatting is based on Keep a Changelog & Gitmoji. For more details regarding the individual PRs and contributors, please refer to our GitHub releases.

v5.0.2 17^th December 2025¶

♻️ Changed¶

• statistics.plot.effects() now defaults to by=None for aggregated totals; use by='component' for the previous behavior

v5.0.1 17^th December 2025¶

👷 Development¶

• Fixed docs deployment in CI workflow

v5.0.0 16^th December 2025¶

Summary: This is a major release that introduces the new FlowSystem-centric API, dramatically simplifying workflows by integrating optimization, results access, and visualization directly into the FlowSystem object. This release also completes the terminology standardization (OnOff → Status) and deprecates the old Optimization/Results workflow (to be removed in v6.0.0).

✨ Added¶

FlowSystem-Centric Architecture: The FlowSystem is now the central hub for all operations:

import flixopt as fx

# Create and configure your system
flow_system = fx.FlowSystem(timesteps)
flow_system.add_elements(boiler, heat_bus, costs)

# Optimize directly on FlowSystem
flow_system.optimize(fx.solvers.HighsSolver())

# Access results via solution Dataset
total_costs = flow_system.solution['costs'].item()
flow_rate = flow_system.solution['Boiler(Q_th)|flow_rate'].values

# Plot with new accessor API
flow_system.statistics.plot.balance('HeatBus')
flow_system.statistics.plot.sankey.flows()

New Accessor-Based API: Four accessor patterns provide organized, discoverable interfaces:

Statistics Accessor: Access aggregated results data with clean, consistent naming:

stats = flow_system.statistics

# Flow data (clean labels, no |flow_rate suffix needed)
stats.flow_rates['Boiler(Q_th)']
stats.flow_hours['Boiler(Q_th)']
stats.sizes['Boiler(Q_th)']
stats.charge_states['Battery']

# Effect breakdown by contributor
stats.temporal_effects['costs']   # Per timestep, per contributor
stats.periodic_effects['costs']   # Investment costs per contributor
stats.total_effects['costs']      # Total per contributor

Comprehensive Plotting API: All plots return PlotResult objects with chainable methods:

# Balance plots for buses and components
flow_system.statistics.plot.balance('ElectricityBus')
flow_system.statistics.plot.balance('Boiler', mode='area')

# Storage visualization with charge state
flow_system.statistics.plot.storage('Battery')

# Heatmaps with automatic time reshaping
flow_system.statistics.plot.heatmap('Boiler(Q_th)|flow_rate', reshape=('D', 'h'))

# Flow-based Sankey diagrams
flow_system.statistics.plot.sankey.flows()
flow_system.statistics.plot.sankey.flows(select={'bus': 'ElectricityBus'})

# Effect contribution Sankey
flow_system.statistics.plot.sankey.effects('costs')

# Method chaining for customization and export
flow_system.statistics.plot.balance('Bus') \
    .update(title='Custom Title', height=600) \
    .to_html('plot.html') \
    .to_csv('data.csv') \
    .show()

Carrier Management: New Carrier class for consistent styling across visualizations:

# Define custom carriers
electricity = fx.Carrier('electricity', '#FFD700', 'kW', 'Electrical power')
district_heat = fx.Carrier('district_heat', '#FF6B6B', 'kW_th')

# Register with FlowSystem
flow_system.add_carrier(electricity)

# Use with buses (reference by name)
elec_bus = fx.Bus('MainGrid', carrier='electricity')

# Or use predefined carriers from CONFIG
fx.CONFIG.Carriers.electricity
fx.CONFIG.Carriers.heat

Transform Accessor: Transformations that create new FlowSystem instances:

# Time selection and resampling
fs_subset = flow_system.transform.sel(time=slice('2023-01-01', '2023-06-30'))
fs_resampled = flow_system.transform.resample(time='4h', method='mean')

# Clustered optimization
params = fx.ClusteringParameters(hours_per_period=24, nr_of_periods=8)
clustered_fs = flow_system.transform.cluster(params)
clustered_fs.optimize(solver)

Rolling Horizon Optimization: Decompose large operational problems into sequential segments:

# Solve with rolling horizon
segments = flow_system.optimize.rolling_horizon(
    solver,
    horizon=192,    # Timesteps per segment
    overlap=48,     # Lookahead for storage optimization
)

# Combined solution available on original FlowSystem
total_cost = flow_system.solution['costs'].item()

# Individual segments also available
for seg in segments:
    print(seg.solution['costs'].item())

Solution Persistence: FlowSystem now stores and persists solutions:

# Optimize and save with solution
flow_system.optimize(solver)
flow_system.to_netcdf('results/my_model.nc4')

# Load FlowSystem with solution intact
loaded_fs = fx.FlowSystem.from_netcdf('results/my_model.nc4')
print(loaded_fs.solution['costs'].item())  # Solution is available!

Migration Helper for Old Results (deprecated, temporary):

# Migrate old result files to new FlowSystem format
fs = fx.FlowSystem.from_old_results('results_folder', 'my_model')
# Or convert Results object directly
fs = results.convert_to_flow_system()

FlowSystem Locking: FlowSystem automatically locks after optimization to prevent accidental modifications:

flow_system.optimize(solver)

# This would raise an error:
# flow_system.add_elements(new_component)  # Locked!

# Call reset() to unlock for modifications
flow_system.reset()
flow_system.add_elements(new_component)  # Now works

NetCDF Improvements: - Default compression level 5 for smaller files - overwrite=False parameter to prevent accidental overwrites - Solution data included in FlowSystem NetCDF files - Automatic name assignment from filename

PlotResult Class: All plotting methods return a PlotResult object containing both: - data: An xarray Dataset with the prepared data - figure: A Plotly Figure object

Component color parameter: Components now accept a color parameter for consistent visualization styling.

💥 Breaking Changes¶

Renamed OnOffParameters → StatusParameters: Complete terminology update to align with industry standards (PyPSA, unit commitment). Old NetCDF files with OnOffParameters are automatically converted on load.

Bus imbalance terminology and default changed: - excess_penalty_per_flow_hour → imbalance_penalty_per_flow_hour - Default changed from 1e5 to None (strict balance) - with_excess → allows_imbalance - excess_input → virtual_supply - excess_output → virtual_demand

Storage charge_state changes: - charge_state no longer has an extra timestep - Final charge state is now a separate variable: charge_state|final

Effect.description now defaults to '' (empty string) instead of None.

Stricter I/O: NetCDF loading is stricter to prevent silent errors. Missing or corrupted data now raises explicit errors.

Validation: Component with status_parameters now validates that all flows have sizes (required for big-M constraints).

♻️ Changed¶

• Renamed BusModel.excess_input → virtual_supply and BusModel.excess_output → virtual_demand for clearer semantics
• Renamed Bus.excess_penalty_per_flow_hour → imbalance_penalty_per_flow_hour
• Renamed Bus.with_excess → allows_imbalance

🗑️ Deprecated¶

All deprecated items will be removed in v6.0.0.

Old Optimization Workflow - Use FlowSystem methods instead:

# Old (deprecated, still works with warning)
optimization = fx.Optimization('model', flow_system)
optimization.do_modeling()
optimization.solve(solver)
results = optimization.results
costs = results.model['costs'].solution.item()

# New (recommended)
flow_system.optimize(solver)
costs = flow_system.solution['costs'].item()

Classes deprecated: - Optimization → Use flow_system.optimize(solver) - ClusteredOptimization → Use flow_system.transform.cluster() then optimize() - SegmentedOptimization → Use flow_system.optimize.rolling_horizon() - Results → Use flow_system.solution and flow_system.statistics - SegmentedResults → Use segment FlowSystems directly

FlowSystem methods deprecated: - flow_system.sel() → Use flow_system.transform.sel() - flow_system.isel() → Use flow_system.transform.isel() - flow_system.resample() → Use flow_system.transform.resample() - flow_system.plot_network() → Use flow_system.topology.plot_network() - flow_system.start_network_app() → Use flow_system.topology.start_network_app() - flow_system.stop_network_app() → Use flow_system.topology.stop_network_app() - flow_system.network_infos() → Use flow_system.topology.network_infos()

Results methods deprecated: - results.flow_rates() → Use flow_system.statistics.flow_rates - results.flow_hours() → Use flow_system.statistics.flow_hours

Migration helpers (temporary, also deprecated): - FlowSystem.from_old_results() → For migrating old result files - Results.convert_to_flow_system() → For converting Results objects

Plotting parameters deprecated: - indexer parameter → Use select instead - heatmap_timeframes parameter → Use reshape_time=(timeframes, timesteps_per_frame) instead - heatmap_timesteps_per_frame parameter → Use reshape_time=(timeframes, timesteps_per_frame) instead - color_map parameter → Use colors instead

🔥 Removed¶

Python version changes: - Dropped Python 3.10 support - Added Python 3.14 support

Classes removed (already renamed/deprecated in v4.x): - OnOffParameters → Use StatusParameters - Calculation → Use Optimization (deprecated) or flow_system.optimize() (recommended) - FullCalculation → Use Optimization (deprecated) or flow_system.optimize() (recommended) - AggregatedCalculation → Use ClusteredOptimization (deprecated) or flow_system.transform.cluster() (recommended) - SegmentedCalculation → Use SegmentedOptimization (deprecated) or flow_system.optimize.rolling_horizon() (recommended) - Aggregation → Use Clustering - AggregationParameters → Use ClusteringParameters - AggregationModel → Use ClusteringModel - CalculationResults → Use Results (deprecated) or flow_system.solution (recommended) - SegmentedCalculationResults → Use SegmentedResults (deprecated)

Modules removed: - calculation.py module → Use optimization.py (deprecated) or FlowSystem methods (recommended)

Functions removed: - change_logging_level() → Use CONFIG.Logging.enable_console()

Properties removed: - FlowSystem.all_elements → Use dict-like interface (flow_system['label'], .keys(), .values(), .items()) - FlowSystem.weights → Use scenario_weights

📝 Docs¶

Comprehensive Tutorial Notebooks - 12 new Jupyter notebooks covering all major use cases:

1. 01-Quickstart - Minimal working example
2. 02-Heat System - District heating with storage
3. 03-Investment Optimization - Optimal equipment sizing
4. 04-Operational Constraints - Startup costs, uptime/downtime
5. 05-Multi-Carrier System - CHP producing electricity and heat
6. 06a-Time-Varying Parameters - Temperature-dependent COP
7. 06b-Piecewise Conversion - Load-dependent efficiency
8. 06c-Piecewise Effects - Economies of scale
9. 07-Scenarios and Periods - Multi-year planning
10. 08-Large-Scale Optimization - Resampling and two-stage
11. 09-Plotting and Data Access - Visualization guide
12. 10-Transmission - Connecting sites with pipelines/cables

New Documentation Pages: - Migration Guide v5 - Step-by-step upgrade instructions - Results & Plotting Guide - Comprehensive plotting documentation - Building Models Guide - Component selection and modeling patterns - FAQ - Common questions and answers - Troubleshooting - Problem diagnosis and solutions

👷 Development¶

New Test Suites: - test_flow_system_locking.py - FlowSystem locking behavior - test_solution_and_plotting.py - Statistics accessor and plotting - test_solution_persistence.py - Solution save/load - test_io_conversion.py - Old file format conversion - test_topology_accessor.py - Network visualization

CI Improvements: - Separate docs build and deploy workflow - Improved test organization with deprecated tests in separate folder

Migration Checklist¶

The old Optimization/Results workflow still works with deprecation warnings. Migrate at your own pace before v6.0.0.

v4.3.5 29^th November 2025¶

Summary: Fix zenodo again

If upgrading from v2.x, see the v3.0.0 release notes and Migration Guide.

v4.3.4 27^th November 2025¶

Summary: Fix zenodo again

If upgrading from v2.x, see the v3.0.0 release notes and Migration Guide.

v4.3.3 27^th November 2025¶

Summary: Fix zenodo again

If upgrading from v2.x, see the v3.0.0 release notes and Migration Guide.

v4.3.2 27^th November 2025¶

Summary: Fix zenodo

If upgrading from v2.x, see the v3.0.0 release notes and Migration Guide.

v4.3.1 26^th November 2025¶

Summary: Add zenodo for better citations and archiving.

If upgrading from v2.x, see the v3.0.0 release notes and Migration Guide.

📝 Docs¶

• Added Zenodo DOI badge to README.md (placeholder, to be updated after first Zenodo release)

👷 Development¶

• Added Zenodo integration for automatic archival and citation
• Created .zenodo.json file for Zenodo metadata configuration
• Repository now ready for DOI assignment upon next release

v4.3.0 25^th November 2025¶

Summary: Penalty is now a first-class Effect - add penalty contributions anywhere (e.g., effects_per_flow_hour={'Penalty': 2.5}) and optionally define bounds as with any other effect.

If upgrading from v2.x, see the v3.0.0 release notes and Migration Guide.

✨ Added¶

• Penalty as first-class Effect: Users can now add Penalty contributions anywhere effects are used:

  fx.Flow('Q', 'Bus', effects_per_flow_hour={'Penalty': 2.5})
  fx.InvestParameters(..., effects_of_investment={'Penalty': 100})
  

• User-definable Penalty: Optionally define custom Penalty with constraints (auto-created if not defined):

  penalty = fx.Effect(fx.PENALTY_EFFECT_LABEL, unit='€', maximum_total=1e6)
  flow_system.add_elements(penalty)
  

♻️ Changed¶

• Penalty is now a standard Effect with temporal/periodic dimensions, and periodic weights in the objective
• Results structure: Penalty now has same structure as other effects in solution Dataset
• Use results.solution['Penalty'] for total penalty value (same as before, but now it's an effect variable)
• Access components via results.solution['Penalty(temporal)'] and results.solution['Penalty(periodic)'] if needed

📝 Docs¶

• Updated mathematical notation for Penalty as Effect

👷 Development¶

• Unified interface: Penalty uses same add_share_to_effects() as other effects (internal only)

v4.2.0 25^th November 2025¶

Summary: Renamed classes and parameters related to Calculation, Aggregation and Results. Fully backwards compatible

If upgrading from v2.x, see the v3.0.0 release notes and Migration Guide.

✨ Added¶

• overwrite parameter when saving results to file. If True, overwrite existing files.

♻️ Changed¶

• Now creates the Results folder even if parents didnt exist

🗑️ Deprecated¶

Class and module renaming: - FullCalculation → Optimization - AggregatedCalculation → ClusteredOptimization - SegmentedCalculation → SegmentedOptimization - CalculationResults → Results - SegmentedCalculationResults → SegmentedResults - Aggregation → Clustering - AggregationParameters → ClusteringParameters - AggregationModel → ClusteringModel - Module: calculation.py → optimization.py - Module: aggregation.py → clustering.py

Old names remain available with deprecation warnings (removed in v5.0.0).

🐛 Fixed¶

• Fixed fix_sizes() docstring/implementation inconsistency for optional ds parameter

👷 Development¶

• Fixed active_timesteps type annotation to include None
• Fixed xarray truth-value ambiguity in main_results buses with excess filter
• Added validation for nr_of_previous_values in SegmentedOptimization to prevent silent indexing bugs

v4.1.4 25^th November 2025¶

Summary: Added file logging encoding to prevent issues

If upgrading from v2.x, see the v3.0.0 release notes and Migration Guide.

🐛 Fixed¶

• Issues with windows file system when logging to file due to non ASCII characters

v4.1.3 25^th November 2025¶

Summary: Re-add mistakenly removed method for loading a config from file

If upgrading from v2.x, see the v3.0.0 release notes and Migration Guide.

🐛 Fixed¶

• Re-added CONFIG.load_from_file() method that was accidentally removed

v4.1.2 24^th November 2025¶

Summary:

If upgrading from v2.x, see the v3.0.0 release notes and Migration Guide.

✨ Added¶

• Exported SUCCESS log level (SUCCESS_LEVEL) for use with logger.log(SUCCESS_LEVEL, ...)
• Added proper deprecation tests

♻️ Changed¶

• logger coloring improved

👷 Development¶

• Fixed Deprecation warnings in tests

v4.1.1 23^rd November 2025¶

Summary: Finalize preparations for removal of all deprecated parameters in v5.0.0

✨ Added¶

• Added missing infos about removal to remaining deprecated parameters and methods

🐛 Fixed¶

• Missing release notes of v4.1.0

v4.1.0 21^st November 2025¶

Summary: Logging migrated from loguru to standard Python logging for stability and security. Simpler API with convenient presets.

If upgrading from v2.x, see the v3.0.0 release notes and Migration Guide.

✨ Added¶

New logging presets:

CONFIG.production('app.log')    # File-only, no console/plots

New logging methods: - CONFIG.Logging.enable_console(level, colored, stream) - Console output with colors - CONFIG.Logging.enable_file(level, path, max_bytes, backup_count) - File logging with rotation - CONFIG.Logging.disable() - Disable all logging - CONFIG.Logging.set_colors(log_colors) - Customize colors

Enhanced formatting: - Multi-line messages with box borders (┌─, │, └─) - Exception tracebacks with proper indentation - Timestamps: 2025-11-21 14:30:45.123

💥 Breaking Changes¶

Logging migration (edge cases only):

Migration:

# Before (v3.6.0-v4.0.0)
CONFIG.Logging.level = 'INFO'
CONFIG.Logging.console = True
CONFIG.apply()

# After (v4.1.0+)
CONFIG.Logging.enable_console('INFO')  # or CONFIG.exploring()

♻️ Changed¶

• Replaced loguru with Python logging + optional colorlog for colors
• Configuration immediate (no CONFIG.apply() needed)
• Log format: [dimmed timestamp] [colored level] │ message
• Logs to stdout by default (configurable)
• SUCCESS level preserved (green, level 25)
• Performance: Expensive operations guarded with logger.isEnabledFor() checks

🗑️ Deprecated¶

• change_logging_level(level) → Use CONFIG.Logging.enable_console(level). Removal in v5.0.0.

🔥 Removed¶

CONFIG methods/attributes: - CONFIG.apply() → Use helper methods directly - CONFIG.Logging.level, .console, .file → Use enable_console()/enable_file() - CONFIG.Logging.verbose_tracebacks, .rich, .Colors, .date_format, .format, .console_width, .show_path, .show_logger_name → Use standard logging - loguru features (logger.opt(), etc.)

🐛 Fixed¶

• TypeError in check_bounds() with loguru-style formatting
• Exception tracebacks not appearing in custom formatters
• Inconsistent formatting between console and file logs

🔒 Security¶

• Removed loguru dependency for reduced supply chain risk

📦 Dependencies¶

• Removed: loguru >= 0.7.0
• Added: colorlog >= 6.8.0, < 7 (optional)

📝 Docs¶

• Preset comparison table in CONFIG.Logging docstring
• Color customization examples
• Migration guide with before/after code

v4.0.0 19^th November 2025¶

Summary: This release introduces clearer parameter naming for linear converters and constraints, enhanced period handling with automatic weight computation, and new sum-over-all-periods constraints for multi-period optimization. All deprecated parameter names continue to work with warnings.

If upgrading from v2.x, see the v3.0.0 release notes and Migration Guide.

✨ Key Features¶

Sum-over-all-periods constraints: New constraint parameters enable limiting weighted totals across all periods: - Effect: minimum_over_periods and maximum_over_periods - Flow: flow_hours_max_over_periods and flow_hours_min_over_periods

# Per-period: limits apply to EACH period individually
effect = fx.Effect('costs', maximum_total=1000)  # ≤1000 per period

# Over-periods: limits apply to WEIGHTED SUM across ALL periods
# With periods=[2020, 2030, 2040] (weights: [10, 10, 10] from 10-year intervals)
effect = fx.Effect('costs', maximum_over_periods=25000)  # 10×costs₂₀₂₀ + 10×costs₂₀₃₀ + 10×costs₂₀₄₀ ≤ 25000

Improved period weight handling: - Period weights now computed automatically from period index (like hours_per_timestep for time) - Weights correctly recalculate when using .sel() or .isel() on periods - Separate tracking of period_weights, scenario_weights, and combined weights

Simplified workflow: - Calculation.solve() now automatically calls do_modeling() if needed

💥 Breaking Changes¶

FlowSystem weights parameter renamed:

# Old (v3.x)
fs = FlowSystem(..., weights=np.array([0.3, 0.5, 0.2]))

# New (v4.0)
fs = FlowSystem(..., scenario_weights=np.array([0.3, 0.5, 0.2]))

Note: If you were previously passing period × scenario weights to weights, you now need to: 1. Pass only scenario weights to scenario_weights 2. Period weights will be computed automatically from your periods index

🗑️ Deprecated Parameters¶

Linear converters (Boiler, CHP, HeatPump, etc.) - descriptive names replace abbreviations: - Flow: Q_fu → fuel_flow, P_el → electrical_flow, Q_th → thermal_flow, Q_ab → heat_source_flow - Efficiency: eta → thermal_efficiency, eta_th → thermal_efficiency, eta_el → electrical_efficiency, COP → cop (lowercase)

Constraint parameters - removed redundant _total suffix: - Flow: flow_hours_total_max → flow_hours_max, flow_hours_total_min → flow_hours_min - OnOffParameters: on_hours_total_max → on_hours_max, on_hours_total_min → on_hours_min, switch_on_total_max → switch_on_max

Storage: - initial_charge_state="lastValueOfSim" → initial_charge_state="equals_final"

All deprecated names continue working with warnings. They will be removed in v5.0.0.

Additional property deprecations now include removal version: - InvestParameters: fix_effects, specific_effects, divest_effects, piecewise_effects - OnOffParameters: on_hours_total_min, on_hours_total_max, switch_on_total_max - Flow: flow_hours_total_min, flow_hours_total_max

🐛 Fixed¶

• Fixed inconsistent boundary checks in linear converters with array-like inputs

👷 Development¶

• Eliminated circular dependencies with two-phase modeling pattern
• Enhanced validation for cross-element references and FlowSystem assignment
• Added helper methods for cleaner data transformation code
• Improved logging and cache invalidation
• Improved argument consistency in internal effect coordinate fitting

v3.6.1 17^th November 2025¶

Summary: Documentation improvements and dependency updates.

If upgrading from v2.x, see the v3.0.0 release notes and Migration Guide.

📦 Dependencies¶

• Updated astral-sh/uv to v0.9.8
• Updated mkdocs-git-revision-date-localized-plugin to v1.5.0

📝 Docs¶

• Improved type specifications in flixopt/types.py for better documentation generation
• Fixed minor mkdocs warnings in flixopt/io.py and mkdocs.yml

v3.6.0 15^th November 2025¶

Summary: Type system overhaul and migration to loguru for logging. If you are heavily using our logs, this might be breaking!

If upgrading from v2.x, see the v3.0.0 release notes and Migration Guide.

✨ Added¶

• New type system (flixopt/types.py):
  • Introduced dimension-aware type aliases using suffix notation (_TPS, _PS, _S) to clearly indicate which dimensions data can have
  • Added Numeric_TPS, Numeric_PS, Numeric_S for numeric data with Time/Period/Scenario dimensions
  • Added Bool_TPS, Bool_PS, Bool_S for boolean data with dimension support
  • Added Effect_TPS, Effect_PS, Effect_S for effect dictionaries with dimension support
  • Added Scalar type for scalar-only numeric values
  • Added NumericOrBool utility type for internal use
  • Type system supports scalars, numpy arrays, pandas Series/DataFrames, and xarray DataArrays
• Lazy logging evaluation - expensive log operations only execute when log level is active
• CONFIG.Logging.verbose_tracebacks option for detailed debugging with variable values

💥 Breaking Changes¶

• Logging framework: Migrated to loguru
  • Removed CONFIG.Logging parameters: rich, Colors, date_format, format, console_width, show_path, show_logger_name
  • For advanced formatting, use loguru's API directly after CONFIG.apply()

♻️ Changed¶

• Code structure: Removed commons.py module and moved all imports directly to __init__.py for cleaner code organization (no public API changes)
• Type handling improvements: Updated internal data handling to work seamlessly with the new type system

🐛 Fixed¶

• Fixed ShareAllocationModel inconsistency where None/inf conversion happened in __init__ instead of during modeling, which could cause issues with parameter validation
• Fixed numerous type hint inconsistencies across the codebase

📦 Dependencies¶

• Updated mkdocs-material to v9.6.23
• Replaced rich >= 13.0.0 with loguru >= 0.7.0 for logging

📝 Docs¶

• Enhanced documentation in flixopt/types.py with comprehensive examples and dimension explanation table
• Clarified Effect type docstrings - Effect types are dicts, but single numeric values work through union types
• Added clarifying comments in effects.py explaining parameter handling and transformation
• Improved OnOffParameters attribute documentation
• Updated getting-started guide with loguru examples
• Updated config.py docstrings for loguru integration

👷 Development¶

• Added test for FlowSystem resampling

v3.5.0 6^th November 2025¶

Summary: Improve representations and improve resampling

If upgrading from v2.x, see the v3.0.0 release notes and Migration Guide.

✨ Added¶

• Added options to resample and select subsets of flowsystems without converting to and from Dataset each time. Use the new methods FlowSystem.__dataset_resample(), FlowSystem.__dataset_sel() and FlowSystem.__dataset_isel(). All of them expect and return a dataset.

💥 Breaking Changes¶

♻️ Changed¶

• Truncate repr of FlowSystem and CalculationResults to only show the first 10 items of each category
• Greatly sped up the resampling of a FlowSystem again

v3.4.1 4^th November 2025¶

Summary: Speed up resampling by 20-40 times.

If upgrading from v2.x, see the v3.0.0 release notes and Migration Guide.

♻️ Changed¶

• Greatly sped up the resampling of a FlowSystem (x20 - x40) by converting to dataarray internally

v3.4.0 1^st November 2025¶

Summary: Enhanced solver configuration with new CONFIG.Solving section for centralized solver parameter management.

If upgrading from v2.x, see the v3.0.0 release notes and Migration Guide.

✨ Added¶

Solver configuration: - New CONFIG.Solving configuration section for centralized solver parameter management: - mip_gap: Default MIP gap tolerance for solver convergence (default: 0.01) - time_limit_seconds: Default time limit in seconds for solver runs (default: 300) - log_to_console: Whether solver should output to console (default: True) - log_main_results: Whether to log main results after solving (default: True) - Solvers (HighsSolver, GurobiSolver) now use CONFIG.Solving defaults for parameters, allowing global configuration - Solver parameters can still be explicitly overridden when creating solver instances - New log_to_console parameter in all Solver classes

♻️ Changed¶

• Individual solver output is now hidden in SegmentedCalculation. To return to the prior behaviour, set show_individual_solves=True in do_modeling_and_solve().

🐛 Fixed¶

• New compacted list representation for periods and scenarios also in results log and console print

📝 Docs¶

• Unified contributing guides in docs and on github

👷 Development¶

• Added type hints for submodel in all Interface classes

v3.3.1 30^th October 2025¶

Summary: Small Bugfix and improving readability

If upgrading from v2.x, see the v3.0.0 release notes and Migration Guide.

♻️ Changed¶

• Improved summary.yaml to use a compacted list representation for periods and scenarios

🐛 Fixed¶

• Using switch_on_total_max with periods or scenarios failed

📝 Docs¶

• Add more comprehensive CONTRIBUTE.md
• Improve logical structure in User Guide

v3.3.0 30^th October 2025¶

Summary: Better access to Elements stored in the FLowSystem and better representations (repr)

If upgrading from v2.x, see the v3.0.0 release notes and Migration Guide.

♻️ Changed¶

Improved repr methods: - Results classes (ComponentResults, BusResults, FlowResults, EffectResults) now show concise header with key metadata followed by xarray Dataset repr - Element classes (Component, Bus, Flow, Effect, Storage) now show one-line summaries with essential information (connections, sizes, capacities, constraints)

Container-based access: - FlowSystem now provides dict-like access patterns for all elements - Use flow_system['element_label'], flow_system.keys(), flow_system.values(), and flow_system.items() for unified element access - Specialized containers (components, buses, effects, flows) offer type-specific access with helpful error messages

🗑️ Deprecated¶

• FlowSystem.all_elements property is deprecated in favor of dict-like interface (flow_system['label'], .keys(), .values(), .items()). Will be removed in v4.0.0.

v3.2.1 29^th October 2025¶

Summary:

If upgrading from v2.x, see the v3.0.0 release notes and Migration Guide.

🐛 Fixed¶

• Fixed resampling of FlowSystem to reset hours_of_last_timestep and hours_of_previous_timesteps properly

👷 Development¶

• Improved issue templates

v3.2.0 26^th October 2025¶

Summary: Enhanced plotting capabilities with consistent color management, custom plotting kwargs support, and centralized I/O handling.

If upgrading from v2.x, see the v3.0.0 release notes and Migration Guide.

✨ Added¶

Color management: - setup_colors() method for CalculationResults and SegmentedCalculationResults to configure consistent colors across all plots - Group components by colorscales: results.setup_colors({'CHP': 'reds', 'Storage': 'blues', 'Greys': ['Grid', 'Demand']}) - Automatically propagates to all segments in segmented calculations - Colors persist across all plot calls unless explicitly overridden - Flexible color inputs: Supports colorscale names (e.g., 'turbo', 'plasma'), color lists, or label-to-color dictionaries - Cross-backend compatibility: Seamless color handling for both Plotly and Matplotlib

Plotting customization: - Plotting kwargs support: Pass additional arguments to plotting backends via px_kwargs, plot_kwargs, and backend_kwargs parameters - New CONFIG.Plotting configuration section: - default_show: Control default plot visibility - default_engine: Choose 'plotly' or 'matplotlib' - default_dpi: Set resolution for saved plots - default_facet_cols: Configure default faceting columns - default_sequential_colorscale: Default for heatmaps (now 'turbo') - default_qualitative_colorscale: Default for categorical plots (now 'plotly')

I/O improvements: - Centralized JSON/YAML I/O with auto-format detection - Enhanced NetCDF handling with consistent engine usage - Better numeric formatting in YAML exports

♻️ Changed¶

• Default colorscale: Changed from 'viridis' to 'turbo' for better perceptual uniformity
• Color terminology: Standardized from "colormap" to "colorscale" throughout for Plotly consistency
• Plotting internals: Now use xr.Dataset as primary data type (DataFrames automatically converted)
• NetCDF engine: Switched back to netcdf4 engine following xarray updates and performance benchmarks

🔥 Removed¶

• Removed unused plotting.pie_with_plotly() method

🐛 Fixed¶

• Improved error messages when using engine='matplotlib' with multidimensional data
• Better dimension validation in results.plot_heatmap()

📝 Docs¶

• Enhanced examples demonstrating setup_colors() usage
• Updated terminology from "colormap" to "colorscale" in docstrings

👷 Development¶

• Fixed concurrency issue in CI
• Centralized color processing logic into dedicated module
• Refactored to function-based color handling for simpler API

v3.1.1 20^th October 2025¶

Summary: Fixed a bug when accessing the effects_per_component dataset in results without periodic effects.

If upgrading from v2.x, see the v3.0.0 release notes and Migration Guide.

🐛 Fixed¶

• Fixed ValueError in effects_per_component when all periodic effects are scalars/NaN by explicitly creating mode-specific templates (via _create_template_for_mode) with correct dimensions

👷 Development¶

• Converted all remaining numpy style docstrings to google style

v3.1.0 19^th October 2025¶

Summary: This release adds faceting and animation support for multidimensional plots and redesigns the documentation website. Plotting results across scenarios or periods is now significantly simpler (Plotly only).

If upgrading from v2.x, see the Migration Guide and v3.0.0 release notes.

✨ Added¶

• Faceting and animation for multidimensional plots: All plotting methods now support facet_by and animate_by parameters to create subplot grids and animations from multidimensional data (scenarios, periods, etc.). Plotly only.
• Flexible data selection with select parameter: Select data using single values, lists, slices, or index arrays for precise control over what gets plotted
• Heatmap fill control: New fill parameter in heatmap methods controls how missing values are filled after reshaping ('ffill' or 'bfill')
• Smart line styling for mixed variables: Area plots now automatically style variables containing both positive and negative values with dashed lines, while stacking purely positive or negative variables

♻️ Changed¶

• Breaking: Selection behavior: Plotting methods no longer automatically select the first value for non-time dimensions. Use the select parameter for explicit selection of scenarios, periods, or other dimensions
• Better error messages: Enhanced error messages when using Matplotlib with multidimensional data, with clearer guidance on dimension requirements and suggestions to use Plotly
• Improved examples: Enhanced scenario_example.py with better demonstration of new features
• Robust validation: Improved dimension validation in plot_heatmap() with clearer error messages

🗑️ Deprecated¶

• indexer parameter: Use the new select parameter instead. The indexer parameter will be removed in v4.0.0
• heatmap_timeframes and heatmap_timesteps_per_frame parameters: Use the new reshape_time=(timeframes, timesteps_per_frame) parameter instead in heatmap plotting methods
• color_map parameter: Use the new colors parameter instead in heatmap plotting methods

🐛 Fixed¶

• Fixed cryptic errors when working with empty buses by adding proper validation
• Added early validation for non-existent periods when using linked periods with tuples

📝 Documentation¶

• Redesigned documentation website with custom css

👷 Development¶

• Renamed internal _apply_indexer_to_data() to _apply_selection_to_data() for consistency with new API naming

v3.0.3 16^th October 2025¶

Summary: Hotfixing new plotting parameter style. Continue to use mode.

Note: If upgrading from v2.x, see the Migration Guide and v3.0.0 release notes.

🐛 Fixed¶

• Reverted breaking change from v3.0.0: continue to use mode parameter in plotting instead of newstyle`
• Renamed new mode parameter in plotting methods to unit_type

📝 Docs¶

• Updated Migration Guide and added missing entries.
• Improved Changelog of v3.0.0

v3.0.2 15^th October 2025¶

Summary: This is a follow-up release to v3.0.0, improving the documentation.

Note: If upgrading from v2.x, see the Migration Guide and v3.0.0 release notes.

📝 Docs¶

• Update the Readme
• Add a project roadmap to the docs
• Change Development status to "Production/Stable"
• Regroup parts in docs

v3.0.1 14^th October 2025¶

Summary: This is a follow-up release to v3.0.0, adding a Migration Guide and bugfixing the docs.

Note: If upgrading from v2.x, see the Migration Guide and v3.0.0 release notes.

📝 Docs¶

• Fixed deployed docs
• Added Migration Guide for flixopt 3

👷 Development¶

• Added missing type hints

v3.0.0 13^th October 2025¶

Summary: This release introduces new model dimensions (periods and scenarios) for multi-period investments and stochastic modeling, along with a redesigned effect sharing system and enhanced I/O capabilities.

Note: If upgrading from v2.x, see the Migration Guide and v3.0.0 release notes.

✨ Added¶

New model dimensions:

• Period dimension: Enables multi-period investment modeling with distinct decisions in each period for transformation pathway optimization
• Scenario dimension: Supports stochastic modeling with weighted scenarios for robust decision-making under uncertainty (demand, prices, weather)
  • Control variable independence across scenarios via scenario_independent_sizes and scenario_independent_flow_rates parameters
  • By default, investment sizes are shared across scenarios while flow rates vary per scenario

Redesigned effect sharing system:

Effects now use intuitive share_from_* syntax that clearly shows contribution sources:

costs = fx.Effect('costs', '€', 'Total costs',
    share_from_temporal={'CO2': 0.2},      # From temporal effects
    share_from_periodic={'land': 100})     # From periodic effects

This replaces specific_share_to_other_effects_* parameters and inverts the direction for clearer relationships.

Enhanced I/O and data handling:

• NetCDF/JSON serialization for all Interface objects and FlowSystem with round-trip support
• FlowSystem manipulation: sel(), isel(), resample(), copy(), __eq__() methods
• Direct access to FlowSystem from results without manual restoring (lazily loaded)
• New FlowResults class and precomputed DataArrays for sizes/flow_rates/flow_hours
• effects_per_component dataset for component impact evaluation, including all indirect effects through effect shares

Other additions:

• Balanced storage - charging and discharging sizes can be forced equal via balanced parameter
• New Storage parameters: relative_minimum_final_charge_state and relative_maximum_final_charge_state for final state control
• Improved filter methods in results
• Example for 2-stage investment decisions leveraging FlowSystem resampling

💥 Breaking Changes¶

API and Behavior Changes:

• Effect system redesigned (no deprecation):
  • Terminology changes: Effect domains renamed for clarity: operation → temporal, invest/investment → periodic
  • Sharing system: The old specific_share_to_other_effects_* parameters were completely replaced with the new share_from_temporal and share_from_periodic syntax (see 🔥 Removed section)
• FlowSystem independence: FlowSystems cannot be shared across multiple Calculations anymore. A copy of the FlowSystem is created instead, making every Calculation independent. Each Subcalculation in SegmentedCalculation now has its own distinct FlowSystem object
• Bus and Effect object assignment: Direct assignment of Bus/Effect objects is no longer supported. Use labels (strings) instead:
  • Flow.bus must receive a string label, not a Bus object
  • Effect shares must use effect labels (strings) in dictionaries, not Effect objects
• Logging defaults (from v2.2.0): Console and file logging are now disabled by default. Enable explicitly with CONFIG.Logging.console = True and CONFIG.apply()

Class and Method Renaming:

• Renamed class SystemModel to FlowSystemModel
• Renamed class Model to Submodel
• Renamed mode parameter in plotting methods to style
• Calculation.do_modeling() now returns the Calculation object instead of its linopy.Model. Callers that previously accessed the linopy model directly should now use calculation.do_modeling().model instead of calculation.do_modeling()

Variable Renaming in Results:

• Investment binary variable: is_invested → invested in InvestmentModel
• Switch tracking variables in OnOffModel:
  • switch_on → switch|on
  • switch_off → switch|off
  • switch_on_nr → switch|count
• Effect submodel variables (following terminology changes):
  • Effect(invest)|total → Effect(periodic)
  • Effect(operation)|total → Effect(temporal)
  • Effect(operation)|total_per_timestep → Effect(temporal)|per_timestep
  • Effect|total → Effect

Data Structure Changes:

• relative_minimum_charge_state and relative_maximum_charge_state don't have an extra timestep anymore. Use the new relative_minimum_final_charge_state and relative_maximum_final_charge_state parameters for final state control

♻️ Changed¶

• Type system overhaul - added clear separation between temporal and non-temporal data throughout codebase for better clarity
• Enhanced FlowSystem interface with improved __repr__() and __str__() methods
• Improved Model Structure - Views and organisation is now divided into:
  • Model: The main Model (linopy.Model) that is used to create and store the variables and constraints for the FlowSystem.
  • Submodel: The base class for all submodels. Each is a subset of the Model, for simpler access and clearer code.
• Made docstrings in config.py more compact and easier to read
• Improved format handling in configuration module
• Enhanced console output to support both stdout and stderr stream selection
• Added show_logger_name parameter to CONFIG.Logging for displaying logger names in messages

🗑️ Deprecated¶

• The agg_group and agg_weight parameters of TimeSeriesData are deprecated and will be removed in a future version. Use aggregation_group and aggregation_weight instead.
• The active_timesteps parameter of Calculation is deprecated and will be removed in a future version. Use the new sel(time=...) method on the FlowSystem instead.
• InvestParameters parameters renamed for improved clarity around investment and retirement effects:
  • fix_effects → effects_of_investment
  • specific_effects → effects_of_investment_per_size
  • divest_effects → effects_of_retirement
  • piecewise_effects → piecewise_effects_of_investment
• Effect parameters renamed:
  • minimum_investment → minimum_periodic
  • maximum_investment → maximum_periodic
  • minimum_operation → minimum_temporal
  • maximum_operation → maximum_temporal
  • minimum_operation_per_hour → minimum_per_hour
  • maximum_operation_per_hour → maximum_per_hour
• Component parameters renamed:
  • Source.source → Source.outputs
  • Sink.sink → Sink.inputs
  • SourceAndSink.source → SourceAndSink.outputs
  • SourceAndSink.sink → SourceAndSink.inputs
  • SourceAndSink.prevent_simultaneous_sink_and_source → SourceAndSink.prevent_simultaneous_flow_rates

🔥 Removed¶

• Effect share parameters: The old specific_share_to_other_effects_* parameters were replaced WITHOUT DEPRECATION
  • specific_share_to_other_effects_operation → share_from_temporal (with inverted direction)
  • specific_share_to_other_effects_invest → share_from_periodic (with inverted direction)

🐛 Fixed¶

• Enhanced NetCDF I/O with proper attribute preservation for DataArrays
• Improved error handling and validation in serialization processes
• Better type consistency across all framework components
• Added extra validation in config.py to improve error handling

📝 Docs¶

• Reorganized mathematical notation docs: moved to lowercase mathematical-notation/ with subdirectories (elements/, features/, modeling-patterns/)
• Added comprehensive documentation pages: dimensions.md (time/period/scenario), effects-penalty-objective.md, modeling patterns
• Enhanced all element pages with implementation details, cross-references, and "See Also" sections
• Rewrote README and landing page with clearer vision, roadmap, and universal applicability emphasis
• Removed deprecated docs/SUMMARY.md, updated mkdocs.yml for new structure
• Tightened docstrings in core modules with better cross-referencing
• Added recipes section to docs

🚧 Known Issues¶

• IO for single Interfaces/Elements to Datasets might not work properly if the Interface/Element is not part of a fully transformed and connected FlowSystem. This arises from Numeric Data not being stored as xr.DataArray by the user. To avoid this, always use the to_dataset() on Elements inside a FlowSystem that's connected and transformed.

👷 Development¶

• Centralized deprecation pattern: Added _handle_deprecated_kwarg() helper method to Interface base class that provides reusable deprecation handling with consistent warnings, conflict detection, and optional value transformation. Applied across 5 classes (InvestParameters, Source, Sink, SourceAndSink, Effect) reducing deprecation boilerplate by 72%.
• FlowSystem data management simplified - removed time_series_collection pattern in favor of direct timestep properties
• Change modeling hierarchy to allow for more flexibility in future development. This leads to minimal changes in the access and creation of Submodels and their variables.
• Added new module .modeling that contains modeling primitives and utilities
• Clearer separation between the main Model and "Submodels"
• Improved access to the Submodels and their variables, constraints and submodels
• Added __repr__() for Submodels to easily inspect its content
• Enhanced data handling methods
  • fit_to_model_coords() method for data alignment
  • fit_effects_to_model_coords() method for effect data processing
  • connect_and_transform() method replacing several operations
• Testing improvements: Eliminated warnings during test execution
  • Updated deprecated code patterns in tests and examples (e.g., sink/source → inputs/outputs, 'H' → 'h' frequency)
  • Refactored plotting logic to handle test environments explicitly with non-interactive backends
  • Added comprehensive warning filters in __init__.py and pyproject.toml to suppress third-party library warnings
  • Improved test fixtures with proper figure cleanup to prevent memory leaks
  • Enhanced backend detection and handling in plotting.py for both Matplotlib and Plotly
  • Always run dependent tests in order

v2.2.0 11^th October 2025¶

Summary: This release is a Configuration and Logging management release.

✨ Added¶

• Added CONFIG.reset() method to restore configuration to default values
• Added configurable log file rotation settings: CONFIG.Logging.max_file_size and CONFIG.Logging.backup_count
• Added configurable log format settings: CONFIG.Logging.date_format and CONFIG.Logging.format
• Added configurable console settings: CONFIG.Logging.console_width and CONFIG.Logging.show_path
• Added CONFIG.Logging.Colors nested class for customizable log level colors using ANSI escape codes (works with both standard and Rich handlers)
• All examples now enable console logging to demonstrate proper logging usage
• Console logging now outputs to sys.stdout instead of sys.stderr for better compatibility with output redirection

💥 Breaking Changes¶

• Console logging is now disabled by default (CONFIG.Logging.console = False). Enable it explicitly in your scripts with CONFIG.Logging.console = True and CONFIG.apply()
• File logging is now disabled by default (CONFIG.Logging.file = None). Set a file path to enable file logging

♻️ Changed¶

• Logging and Configuration management changed
• Improved default logging colors: DEBUG is now gray (\033[90m) for de-emphasized messages, INFO uses terminal default color (\033[0m) for clean output

🗑️ Deprecated¶

• change_logging_level() function is now deprecated in favor of CONFIG.Logging.level and CONFIG.apply(). Will be removed in version 3.0.0.

🔥 Removed¶

• Removed unused config.merge_configs function from configuration module

👷 Development¶

• Greatly expanded test coverage for config.py module
• Added @pytest.mark.xdist_group to TestConfigModule tests to prevent global config interference

v2.1.11 5^th October 2025¶

Summary: Important bugfix in Storage leading to wrong results due to incorrect discharge losses.

♻️ Changed¶

• Using h5netcdf instead of netCDF4 for dataset I/O operations. This follows the update in xarray==2025.09.01

🐛 Fixed¶

• Fix charge_state Constraint in Storage leading to incorrect losses in discharge and therefore incorrect charge states and discharge values.

📦 Dependencies¶

• Updated renovate.config to treat CalVer packages (xarray and dask) with more care
• Updated packaging configuration

v2.1.10 29^th September 2025¶

Summary: This release is a Documentation and Development release.

📝 Docs¶

• Improved CHANGELOG.md formatting by adding better categories and formating by Gitmoji.
• Added a script to extract the release notes from the CHANGELOG.md file for better organized documentation.

👷 Development¶

• Improved renovate.config
• Sped up CI by not running examples in every run and using pytest-xdist

v2.1.9 23^rd September 2025¶

Summary: Small bugfix release addressing network visualization error handling.

🐛 Fixed¶

• Fix error handling in network visualization if networkx is not installed

v2.1.8 22^nd September 2025¶

Summary: Code quality improvements, enhanced documentation, and bug fixes for heat pump components and visualization features.

✨ Added¶

• Extra Check for HeatPumpWithSource.COP to be strictly > 1 to avoid division by zero
• Apply deterministic color assignment by using sorted() in plotting.py
• Add missing args in docstrings in plotting.py, solvers.py, and core.py.

♻️ Changed¶

• Greatly improved docstrings and documentation of all public classes
• Make path handling to be gentle about missing .html suffix in plotting.py
• Default for relative_losses in Transmission is now 0 instead of None
• Setter of COP in HeatPumpWithSource now completely overwrites the conversion factors, which is safer.
• Fix some docstrings in plotting.py
• Change assertions to raise Exceptions in plotting.py

🐛 Fixed¶

Core Components: - Fix COP getter and setter of HeatPumpWithSource returning and setting wrong conversion factors - Fix custom compression levels in io.save_dataset_to_netcdf - Fix total_max did not work when total min was not used

Visualization: - Fix color scheme selection in network_app; color pickers now update when a scheme is selected

📝 Docs¶

• Fix broken links in docs
• Fix some docstrings in plotting.py

👷 Development¶

• Pin dev dependencies to specific versions
• Improve CI workflows to run faster and smarter

v2.1.7 13^th September 2025¶

Summary: 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

v2.1.6 2^nd September 2025¶

Summary: Enhanced Sink/Source components with multi-flow support and new interactive network visualization.

✨ Added¶

• Network Visualization: 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
  • Note: This is still experimental and might change in the future

♻️ Changed¶

• Multi-Flow Support: Sink, Source, and SourceAndSink now accept multiple flows as inputs and outputs instead of just one. This enables modeling more use cases with these classes
• Flow Control: Both Sink and Source now have a prevent_simultaneous_flow_rates argument to prevent simultaneous flow rates of more than one of their flows

🗑️ 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

🐛 Fixed¶

• Fixed testing issue with new linopy version 0.5.6

👷 Development¶

• Added dependency "nbformat>=4.2.0" to dev dependencies to resolve issue with plotly CI

v2.1.5 8^th July 2025¶

🐛 Fixed¶

• Fixed Docs deployment

v2.1.4 8^th July 2025¶

🐛 Fixed¶

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

v2.1.3 8^th July 2025¶

🐛 Fixed¶

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

v2.1.2 14^th June 2025¶

🐛 Fixed¶

• Storage losses per hour were not calculated correctly, as mentioned by @brokenwings01. This might have led to issues when 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.

v2.1.1 8^th May 2025¶

♻️ Changed¶

• Improved docstring and tests

🐛 Fixed¶

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

v2.1.0 11^th April 2025¶

✨ 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

💥 Breaking Changes¶

• 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

🐛 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)

v2.0.1 10^th April 2025¶

✨ 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

v2.0.0 29^th March 2025¶

Summary: 💥 MAJOR RELEASE - Complete framework migration from Pyomo to Linopy with redesigned architecture.

✨ Added¶

Model Capabilities: - 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

Results & Data: - 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

💥 Breaking Changes¶

Framework Migration: - Optimization Engine: Complete migration from Pyomo to Linopy optimization framework - Package Import: Framework renamed from flixOpt to flixopt (import flixopt as fx) - Data Architecture: Redesigned data handling to rely on xarray.Dataset throughout the package - Results System: Results handling completely redesigned with new CalculationResults class

Variable Structure: - 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

🔥 Removed¶

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

🐛 Fixed¶

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

📝 Docs¶

• Google Style Docstrings throughout the codebase