Solar Panel

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Description

The Solar Panel is a Power Source that produces electrical power from incident sunlight absorbed by the panel surface. Power generation depends on the angle between the panel and sun, the panel area, solar flux, and conversion efficiency. The panel can also account for planetary albedo reflection when an Albedo Model is attached.

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Example Use Cases

• Power Generation: Simulate primary spacecraft power generation from solar arrays.
• Attitude-Dependent Power: Evaluate how spacecraft orientation affects available power.
• Eclipse Analysis: Model power reduction during planetary shadow transits.

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Module Implementation

The solar panel computes power output based on solar geometry, panel properties, and environmental conditions.

Projected Area

The effective area exposed to sunlight is computed from the dot product of the sun direction and panel normal:

$$A_{\text{proj}}=A\cdot \max (\hat{s}\cdot \hat{n},0)$$

where $A$ is the panel area, $\hat{s}$ is the unit vector toward the sun in body frame, and $\hat{n}$ is the panel normal in body frame.

Power Output

The electrical power generated by the panel is:

$$P=(1-\sigma )\cdot \alpha \cdot \Phi \cdot A_{\text{proj}}\cdot \eta$$

where $\sigma$ is the shadow factor, $\alpha$ is the solar absorbance, $\Phi$ is the solar flux (including albedo contribution if applicable), and $\eta$ is the conversion efficiency.

Albedo Contribution

When an Albedo Model is attached, the reflected flux from nearby celestial bodies is added to the direct solar flux before power calculation.

Self-Shadowing

When enabled in a visualization environment, ray-casting can determine additional shadowing from spacecraft geometry. The ray-cast density controls the resolution of this calculation.

Sun Angle Override

For advanced use cases, the sun angle calculation can be overridden with user-provided vectors using the SetSunAngle method. This allows external systems to provide pre-computed sun direction and panel normal vectors in the body frame, bypassing the default calculation from transform and planet state messages. The override can be cleared with ResetSunAngleCalculation to return to the standard computation.

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Assumptions/Limitations

• The panel is modeled as a flat surface with uniform properties.
• The shadow factor for non-celestial shadowing must be set manually unless self-shadowing is enabled.
• Peak power limiting is applied when a positive PeakPower value is configured.