Sol 0Local solar time 00:00Sun elevation 0°On the panel 0 W/m²Array 0 WBattery 0 %Dust: panel passes 100 %FPS 0

Drag to orbit, wheel or pinch to zoom. The Sun, sky and shadows follow real Mars geometry (latitude, season, time of sol). The blue-cell panel above the rover turns with the mode you choose and fades to red-brown as dust settles. The giant planet in the sky is artistic licence (not visible like this from Mars).

Mars Rover Solar Power: Sol Energy Budget, Dust and Seasons

Can a solar rover live on its array? Move the site, the season and the dust, and watch the battery through day, night and years of sols.

Site and weather

Solar array

Rover and battery

Time

Live readouts

Today: array power and rover load (W)

Battery and array transmission by sol

Energy from the array across the Martian year

Same latitude, panel, opacity and dust level as now; only the season changes. The dip near Ls 70° is aphelion; Mars receives about 45 % more sunlight at perihelion (Ls 251°).

Experiment: a 200-sol mission

Runs the same model (no graphics) for 200 sols from sol 0 with the current settings and a fixed random sequence for wind cleaning. Try the planner on and off, and the dusty-panels preset.

Independent numerical checks

Controls

Drag / one finger: orbit; wheel / pinch: zoom. Time scale speeds the day and night; 1 sol takes about three minutes.
Array mode: flat on the deck, fixed tilt (tilt and compass azimuth sliders, 0° = north), or a two-axis sun tracker (a model upper bound).
The ground-slope slider tilts the whole rover toward north (+) or south (−): it changes both the panel angle and the power needed to climb.
The drive planner decides each morning how long to drive from the battery level and the energy forecast, so the rover does not drive itself into safe mode.

The science

Sun geometry. Mars follows a Kepler orbit with a = 1.5237 AU and e = 0.0934. The true anomaly is ν = L_s − 251° and the distance is r = a (1 − e²) / (1 + e cos ν), so the flux at the top of the atmosphere is S = 1361 / r² W/m² (713 W/m² at perihelion, 490 at aphelion). The declination follows sin δ = sin ε sin L_s with obliquity ε = 25.19°. For latitude φ and hour angle h the Sun's elevation obeys sin(elev) = sin φ sin δ + cos φ cos δ cos h; the sol is 24 h 39 m 35 s long.

Atmosphere. Dust opacity τ dims the direct beam by Beer–Lambert, T_b = exp(−τ / cos z). Scattered light is an empirical closure, G_d = 0.45 S cos z (1 − T_b) e^{−0.25 τ}, so under a thick dust storm the array still gets sky light. It is illustrative, not a radiative-transfer calculation; the check below only verifies that it never creates energy.

Array. P = A η(T) f_dust [S_n cos θ + G_d (1 + n_up)/2], where cos θ is the angle between the Sun and the panel normal, the cell efficiency falls 0.2 % per kelvin above 25 °C (cell temperature = air + 18 K) and the dust factor drops by a fixed percentage every sol, jumping back when wind cleans the cells (as happened on the real Mars Exploration Rovers).

Loads and battery. Always-on avionics, a survival heater max(0, UA (T_set − T_air) − P_RHU) (UA = 0.45 W/K, 6 W from radioisotope heater units), driving (65 W of electronics plus mechanical power m g (C_rr + sin γ) v / η), science and communications. The battery charges with efficiency 0.92, discharges with 0.95, clips at full and trips to safe mode (only avionics and heater) under 12 % until it recovers to 45 %. Time steps are 0.02 h live and 0.1 h in the mission run.

Simplifications. No spectral or incidence-angle losses, no shadowing of the panel by the rover or the terrain horizon, no wheel slip, no thermal mass and no dust storms that evolve in time (the opacity is constant). Battery efficiency is constant. The season advances 0.54° of L_s per sol. Constants are generic round numbers for a 185 kg rover. Not a mission design tool. Models built with Blender, scene by Three.js.