A high-precision, Rust-based CLI tool for calculating accurate sun position, sunset and sunrise times, twilight phases, UV index, and estimating solar panel energy yields. Argos support to display info in GNOME Shell status bar.

Uses high-resolution, gridded Copernicus ADS data (Ozone, AOD, and Diffuse UV Albedo). This data is embedded into the compiled binary for O(1) access. Formula-based version available with option --formula-calcs.

suntimes-rs goes beyond simple sunrise/sunset times; it features a robust solar energy modeling engine capable of optimizing panel tilt and azimuth, supporting solar tracking systems (dual-axis, HSAT, VSAT), and generating seasonal adjustment schedules to maximize your energy production.

Purpose: match NOAA sunrise/sunset tables

Applies: Upper limb (−0.266°) Geometric horizon dip Standard refraction only (1013.25 hPa, 15 °C)

Does NOT apply: Pressure-from-altitude Height-of-eye atmospheric correction This is what NOAA effectively does.

Purpose: match JPL Horizons Observer Table Applies: Observer altitude in SPA geometry Standard refraction No geometric dip correction

Does NOT apply: Horizon dip Pressure-from-altitude

Purpose: physically realistic observer model Applies: Observer altitude in geometry Geometric horizon dip Pressure estimated from altitude Temperature from user

Does NOT apply: Any NOAA/Horizons compatibility constraints

This is not directly comparable to Horizons — by design.

Assuming you have already installed Argos.

$ cat > ~/.config/environment.d/argos.conf  << END
> ARGOS_SUNTIMES_ENABLE=true
ARGOS_SUNTIMES_LONGITUDE=5.5
ARGOS_SUNTIMES_LATITUDE=45.5
ARGOS_SUNTIMES_ALTITUDE=120
> END

$ ln -s ~/.cargo/bin/suntimes-rs ~/.config/argos/suntimes.5s.bin

And relogin. You can also use bash script as the argos binary so changing parameters is easier:

#!/bin/sh
exec suntimes-rs --latitude ...

suntimes-rs --latitude 60.17 --longitude 24.94 --solarpanel-size 10

suntimes-rs --latitude 60.17 --longitude 24.94 \
  --solarpanel-size 25 \
  --solarpanel-tilt 40 \
  --solarpanel-azimuth 170 \
  --solarpanel-efficiency 0.22 \
  --linke-turbidity 2.5 \
  --albedo 0.3

./suntimes-rs --latitude 60.2 --longitude 24.9 --solarpanel-size 10
--solarpanel-yearly-adjustments 4

./suntimes-rs --latitude 60.2 --longitude 24.9 --solarpanel-size 10
--solarpanel-yearly-adjustments 4 --solarpanel-tilt-range 25-55

./suntimes-rs --latitude 60.2 --longitude 24.9 --solarpanel-size 10
--solarpanel-hsat

./suntimes-rs --latitude 60.2 --longitude 24.9 --solarpanel-size 10
--solarpanel-vsat

./suntimes-rs --latitude 60.2 --longitude 24.9 --solarpanel-size 10
--solarpanel-tracking

--solarpanel-find-optimum: Find optimum fixed tilt and azimuth for maximum daily energy

Valid combinations

suntimes-rs --latitude 60.7 --longitude 22.94 --argos --solarpanel-size 10

This program computes solar positions, sunrise/sunset, and twilight times using high-precision astronomical models. Its numerical validity depends on several underlying models, each with different applicability ranges. The effective supported epoch is the intersection of these models.

Supported years: −500 to +5000 (astronomical year numbering) Location to timezone feature (--timezone location) is reliable only from year 1970 onwards. Calendar system: proleptic Gregorian Time representation: UTC or modern IANA time zones Dates outside this range are rejected because required physical models (ΔT) are not available.

Solar geometry (SPA)

• Uses the NREL Solar Position Algorithm (SPA)
• Valid approximately from −2000 to +6000
• Provides sub-arcminute accuracy for solar azimuth and altitude

This is not the limiting factor.

ΔT (Terrestrial Time − Universal Time) ΔT is required to convert between Earth rotation time and ephemeris time ΔT is estimated, not known exactly, outside the modern era The ΔT model used by this program is defined for years ≥ −500 For earlier years, ΔT uncertainty becomes too large and the model refuses to extrapolate.

--timezone location uses about 30 ms on startup. tzf-rs loads a binary map of the entire world’s timezone boundaries. This map is stored as a Protocol Buffer.