[Bug]: Myopic window truncates capex loan payments, underreports cost

[DavidLikesLearning]

Bug Description

In myopic mode, loan_cost() cuts every tech's amortized investment cost at the end of the myopic view window, not the study horizon boundary. Technologies built more than view_depth periods from final period only pays a fraction of its investment costs.

CAUSE: temoa/components/costs.py::loan_cost() caps the recognized loan repayment at min(lifetime_process, p_e - vintage) (undiscounted branch; the discounted branch applies the same cap inside annuity_to_pv(GDR, min(lifetime_process, p_e - vintage))):

res = (
    annuity
    * lifetime_loan_process / lifetime_process
    * min(lifetime_process, p_e - vintage)   # truncation

but p_e is defined as

p_e = model.time_future.last()  
# End point of modeled horizon

Steps to Reproduce

We subset CONUS 26z OEO database so we can run this on a small personal laptop:

We subset four regions in the Southeast. We look at the four most representative weeks for all periods, looking at Sunday, Monday, Tuesday. To recreate this minimal dataset, run python build_subset.py in the same directory as the OEO 26 zone CONUS database .sqlite from https://datadocs.openenergyoutlook.org/en/latest/datasets.html.

1. build local subset
2. remove distributed technologies to avoid infeasibility
3. run temoa on the subset with myopic mode (<2 min)
4. run truncation verification. note limited years of loan payments

Code or Configuration Example

We start in a folder with config_myopic.toml (added as a .txt file to please the github gods), strip_dg1.sql, verify_truncation.py, and subset_26zone_conus.py.

strip_dg1.sql

config_myopic.txt

subset_26zone_conus.py

verify_truncation.py

source ../temoa_env/bin/activate

# CHANGE PATH BELOW TO OEO CONUS database .sqlite file

python subset_26zone_conus.py --source /path/to/v1-26z_conus_servers.sqlite --out subset_myopic.sqlite --regions SRCA SRCE SRSE SRSG --periods 2027 2030 2035 2040 --horizon-boundary 2045 --seasons p4 p19 p30 p48 --hours 1-48 --fuel-census-division east_south_central south_atlantic mountain --overwrite

python -c "import sqlite3; d=sqlite3.connect('subset_myopic.sqlite'); d.executescript(open('strip_dg1.sql').read()); d.commit(); print('FK check:', d.execute('PRAGMA foreign_key_check').fetchall())"

temoa run config_myopic.toml --silent

python verify_truncation.py subset_myopic.sqlite --view-depth 1 --csv truncation.csv

Expected Behavior

Technologies should make loan payments for said technologies until the end of their planning horizon.

Actual Behavior

Technologies built in period p only make loan payments during that period, automatically making myopic technologies cheaper by about a half or a third of the price.

Environment

Please provide details about your environment. This helps us reproduce the issue.

• Operating System: macOS 26.2, Apple Silicon (arm64), Darwin kernel 25.2.0
• Python Version: 3.13.5
• Project Version: 4.0.0a2
• Relevant Dependencies:

Pyomo 6.9.5
highspy 1.14.0 (HiGHS appsi_highs solver)
numpy 2.4.4
pandas 3.0.2
scipy 1.17.1
openpyxl 3.1.5
temoa_env built from latest project version.

Checklist

• [ x] I have searched existing issues to ensure this bug hasn't already been reported.
• [x ] I have provided clear steps to reproduce the bug.
• [ x] I have provided a minimal, reproducible code example (if applicable).
• [ x] I have included any relevant error messages or stack traces.
• [ x] I have described the expected and actual behavior.