Capacity Output

Contents

Overview | Columns | Variable Types | Configuration | Assumptions | Examples | Cross-Period Summary | See Also

Overview

File: capacity.csv

capacity.csv records the capacity of every edge and storage component in the system after the optimization. For each component, five capacity variables are reported: total optimal capacity, new capacity added in this period, capacity retired, capacity retrofitted, and existing (pre-installed) capacity at the start of the period.

This is one of the most important output files. Capacity decisions are the primary investment variables in Macro — the flows and costs all depend on the capacity choices made here.

The file uses long format by default: every (component, variable) combination occupies one row. However, to facilitate easier analysis of capacity breakdowns, an optional wide format pivots the variable column into separate columns for each capacity type (total, new, retired, existing, retrofitted).

Columns

Variable Types

The variable column takes one of five values, all reported for each component in the same file:

Configuration

Assumptions

• Units follow whatever unit system you define in your inputs. The default assumption in the Macro documentation is MW for power capacity and MWh for energy storage capacity. Capacity is reported per component (edge or storage), not per asset. A single asset may contain multiple components with separate capacity rows.
• Components without capacity — components with has_capacity = false are excluded from the output. Only components where has_capacity = true appear in capacity.csv. All storage components are always included (all storages have capacity variables by definition).
• Multi-period models — each period's results_period_N/ directory contains capacity values reflecting the capacity available during that planning period. Per the multi-period accounting assumptions, new capacity comes online at the beginning of a period. existing_capacity reflects the carry-over from the previous period, and new_capacity reflects investments made during period N.
• Single-period models — existing_capacity is the user-specified existing_capacity from the input data. capacity = existing_capacity + new_capacity - retired_capacity.
• Capacity is reported per component, not per asset. An asset such as a Battery will produce rows for each of its edges (charge, discharge) and its storage component separately. Especially for symmetric battery systems, users interested in the total installed battery capacity should typically look at the storage component or the discharge edge.

Examples

Default Long Format

Wide Format (OutputLayout.Capacity = "wide")

Writing Capacity Programmatically

• write_capacity allows you to write capacity data to a custom file path, with optional filters for commodity, asset type, or component type. This is useful for exporting subsets of the capacity data or for writing to a different location.
• get_optimal_capacity returns the capacity data as a DataFrame without writing a file. This is useful for programmatic access to capacity values within Julia.

# After solving:
(case, model) = solve_case(case_path, optimizer)

# Export capacity for a specific period/system
system = case.systems[1];
write_capacity("my_capacity.csv", system)

# Export only electricity capacity
write_capacity("elec_capacity.csv", system, commodity="Electricity")

# Export only Battery and VRE assets
write_capacity("storage_vre.csv", system, asset_type=["Battery", "VRE"])

# Get capacity as a DataFrame (no file written)
df = get_optimal_capacity(system)

Cross-Period Summary

File: capacity_summary.csv

For multi-period cases, write_capacity_summary combines every period's capacity results into a single file, written once at the top level of the results directory (see Output Directory Structure) rather than inside any individual results_period_N/ folder. It is not written for single-period cases.

Each period is labeled either by its calendar year (if StartYear is set in case_settings.json) or by its 1-based period index (if not) — see the StartYear row in Configuration. :existing_capacity is only included for the first (earliest) period, since for every later period it is always equal to the previous period's final capacity and so is redundant.

Like capacity.csv, the summary supports both long and wide layouts, controlled independently via OutputLayout.CapacitySummary.

Long Format (default)

Identical schema to capacity.csv, stacked across every period, with the period label column (year or period) placed right before value:

Wide Format (OutputLayout.CapacitySummary = "wide")

One row per component; columns are <variable>_<year> (or <variable>_<period>) for every variable/period combination actually present, in chronological order:

A component that doesn't exist yet in the first period (e.g. a technology only built in a later period) gets 0.0 for its earlier-period columns rather than being omitted.

Writing the Summary Programmatically

write_capacity_summary can also be called directly, given a chronologically-ordered vector of per-period DataFrames (as returned by write_capacity) and a layout ("long" or "wide"):

(case, model) = solve_case(case_path, optimizer)

period_results = [write_capacity(joinpath("period_$i.csv"), system, 1.0) for (i, system) in enumerate(case.systems)]
write_capacity_summary(output_dir, period_results, "wide")

See Also

• Outputs Overview — overview of all output files and settings
• Costs Output — investment and O&M costs associated with capacity decisions
• Financial Assumptions — how investment costs are annualized from CAPEX
• Multi-Period Accounting — how capacity evolves across planning periods
• Edges — edge investment parameters (can_expand, existing_capacity, etc.)
• Storage — storage investment parameters