Costs Output

Contents

Overview | System-Level Cost Files | Breakdown Cost Files | Cost Categories | Configuration | Assumptions | Examples | See Also

Overview

Files: costs.csv, undiscounted_costs.csv, costs_by_type.csv, costs_by_zone.csv, undiscounted_costs_by_type.csv, undiscounted_costs_by_zone.csv

Macro writes six cost output files after each solve. Together they provide a complete picture of the system's total expenditure, broken down by discounting status, cost category, asset type, and zone.

• costs.csv and undiscounted_costs.csv — system-wide totals (three rows: fixed, variable, total)
• costs_by_type.csv and undiscounted_costs_by_type.csv — breakdown by asset type and cost category
• costs_by_zone.csv and undiscounted_costs_by_zone.csv — breakdown by zone and cost category

All values represent costs for the entire modeled period, not annualized values.

System-Level Cost Files

costs.csv (discounted) and undiscounted_costs.csv

These files contain exactly three rows — one for fixed costs, one for variable costs, and one for the total. All metadata columns are set to "all" or "missing" because the values are system-wide aggregates with no per-asset or per-zone breakdown.

variable values in costs.csv (discounted)

variable values in undiscounted_costs.csv

Breakdown Cost Files

costs_by_type.csv and undiscounted_costs_by_type.csv

These files break costs down by asset type (e.g., ThermalPower{NaturalGas}, Battery, VRE) and cost category (e.g., Investment, Fuel). A final row with type = "Total" gives the system-wide sum for each category.

costs_by_zone.csv and undiscounted_costs_by_zone.csv

These files break costs down by zone (location) and cost category. A final row with zone = "Total" gives the system-wide sum.

Cost Categories

The category column in the breakdown files takes one of the following values. The same category names appear in both the discounted (costs_by_type.csv, costs_by_zone.csv) and undiscounted (undiscounted_costs_by_type.csv, undiscounted_costs_by_zone.csv) files — the distinction is in how the values are computed, not in the category names themselves.

Internally, Macro splits categories into two groups that use different discounting multipliers.

Fixed cost categories:

Variable operating cost categories

All follow the same discounting structure. For each category, $C$ is the category-specific annualized cost computed from the representative time steps: $C = \sum_t w_t \times \text{unit cost} \times \text{flow}_t$, where $w_t$ is the subperiod weight and the unit cost varies by category (see description table below). The discounted value is $C$ multiplied by the present-value annuity factor (PVAF) for the period length and then multiplied by the period discount factor (DF). The undiscounted value is simply $C$ multiplied by the period length.

Notation and Formulas

The following notation is used throughout:

The present-value annuity factor (PVAF) converts a stream of $N$ annual payments into a present value at year 0:

\[\text{PVAF}(DR, N) = \sum_{t=1}^{N} \frac{1}{(1+DR)^t} = \frac{1-(1+DR)^{-N}}{DR} = \frac{1}{\text{CRF}(DR, N)}\]

The period discount factor brings a value at the start of period $p$ back to the case base year:

\[\text{DF}(DR, N_i) = \frac{1}{(1+DR)^{N_i}}\]

Note: when $DR = 0$, $\text{PVAF}(0, N) = N$, $\text{CRF}(0, N) = 1/N$, and $\text{DF}(0, N_i) = 1$.

Given these definitions, the cost categories are computed as follows:

Fixed cost categories:

Variable cost categories:

Configuration

Assumptions

• Period-wide totals, not annualized. All cost values represent total costs over the entire modeled period, not an annual rate. In a single-period model this is typically one year. In a multi-period model, costs for period N represent the costs incurred over the length of that period (see PeriodLengths in case_settings.json).
• Discounting. Discounted costs in costs.csv are present values referenced to the base year of the model. The discount rate is the DiscountRate field in case_settings.json. See Multi-Period Accounting for the full discounting formula.
• Objective value. DiscountedTotalCost in costs.csv equals the value of the optimization objective function (modulo any numerical scaling applied internally). Minimizing this quantity is what the optimizer does.
• Units. Costs are in the monetary units used in your input data (typically $). Macro does not enforce a specific currency; it is the user's responsibility to ensure consistent units across all input cost parameters.
• Non-served demand costs. These are counted as variable costs in the system-level files and appear as the NonServedDemand category in the breakdown files. They are a penalty, not actual expenditure — they incentivize the optimizer to meet demand.
• Supply costs. Costs associated with commodity supply (e.g., natural gas supply nodes with a price) appear under the Supply category.

Examples

costs.csv (wide format, typical single-period model)

With OutputLayout.Costs = "wide", the three rows are pivoted into a single row with one column per cost variable:

The metadata columns (case_name, commodity, zone, resource_id, component_id, type, year) are dropped automatically in wide format.

undiscounted_costs.csv (wide format)

costs_by_type.csv (default long format)

costs_by_type.csv (wide format)

With OutputLayout.Costs = "wide", cost categories are pivoted to columns and a Total column is added:

costs_by_zone.csv (default long format)

costs_by_zone.csv (wide format)

Reading Costs in Julia

using CSV, DataFrames

costs = CSV.read("results/costs.csv", DataFrame)
costs_by_type = CSV.read("results/costs_by_type.csv", DataFrame)

# Get total investment cost
total_investment = costs_by_type[costs_by_type.type .== "Total" .&& costs_by_type.category .== "Investment", :value][1]

See Also

• Outputs Overview — overview of all output files and settings
• Capacity Output — the capacity decisions that drive investment costs
• Financial Assumptions — Capital Recovery Factor calculation and WACC
• Multi-Period Accounting — present-value discounting across periods
• Non-Served Demand Output — non-served demand penalty costs