Solar panels

SaVoir can model the geometry of solar panels and evaluate solar power availability for a satellite during a time period.

Creating solar panels

- Right click menu over any satellite in the satellite scenario pane, and selecting the Solar panel wizard

Solar panels will be shown on the satellite scenario tree under the corresponding satellite

Configuring solar panels

- Power: Maximum power capacity (watts) in conditions of perfect exposition to sun, i.e. with normal axis pointing perfectly to the sun.

- Arrow length: Just for display and verification, length of the normal axis arrow

- Normal axis: Unit vector x,y,z coordinates of the solar panel normal axis, in the satellite body moving reference (X = velocity vector, Z: Nadir looking towards Earth center, Y: Left looking normal), applicable in the case of Motion = FIXED

- Rotating axis: Unit vector x,y,z coordinates of the solar panel rotating axis, in the satellite body moving reference (X = velocity vector, Z: Nadir looking towards Earth center, Y: Left looking normal), applicable in the case of Motion = ROTATING

- Zenith over axis: It is the angle between the solar panel surface normal, and normal to the rotation axis, applicable in the case of Motion = ROTATING. By defualt this angle is zero, indicating that the surface normal is perpendicular to the rotaating axis

(4) Operate the x, y and z axis coordinates to obtain an arrow befitting the expected solar panel outward normal axis. The values of x,y,z are not boundary limited, but internally they are normalised to represent a unit vector.

Fixed solar panels

In the case of fixed solar panels, arrows will show the normal or normals to the solar panes. An additional arrow points to the current sun location. Each normal is tagged with a value in watts, which is the nominal solar panel power multiplied by the cosine of the angle between the solar panel normal and the vector to the sun. In the picture below we see a satellite with four fixed solar panels. Each panel offers a maximum of 100 watts. Because of being in opposite sides of the satellite body, only two panels offer some surface to the sun. One of them, yields 95 watts, and the other 17 watts, at that particular moment in time. The other two panels yield 0 watts.

Rotating solar panels

In the case of Rotating solar panels, the rotting axis is shown as line crossing through the satellite body. The 3D model should show the rotating solar panel pointing in an optimal way to the sun, and the solar panel normal will be displayed too. In the picture below, the satellite Sentinel-3 has been configured with a single 1000 watt solar panel, and with a "Zenith over axis" value of 23 degrees, to indicate the solar panel tilt with respect to the rotating axis.

Evaluating electrical power available

- Generate a mission plan in which the satellite shows on the Gantt view. For example a visibility analysis, or a swath intersection analysis

- On the Gantt View, right click on the satellite icon, and run the "Solar panel power" tool. SaVoir will calculate the power profile in watts

The power profile is calculated adding the contribution of all selected solar panels, taking into account on a time bases:

- Solar panel orientation with respect to the sun, accounting for the angle between sun direction and solar panel normal axis

- Reduced solar power due to partial sun occultation during eclipse penumbra and lunar eclipses

- For rotating solar panels, the power obtained will account for the optimised panel orientation.

The resulting profile can be exported to excel (right click menu on the types bar on the Gantt view)