Solar Panel

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Description

The Solar Panel is a special type of Power Source that is able to produce power from the Solar Model, acting upon an area. The solar panel is designed as a component that can be added to a spacecraft or ground station and produce power that can be stored in a battery. The solar panel also takes in Solar Model information, based on whether the solar panel is hidden behind a planet from the sun.

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Example Use Cases

• Power Generation: Generating power for components or a Battery charge onboard a spacecraft.
• Albedo Detection: Calculating the total albedo being produced by the Earth at a location in orbit.

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Module Implementation

The solar panel can produce power $W_{\mathrm{out}}$ based on the solar flux at the pointing in time $F$ and the angle relative between the sun direction vector $\hat{\text{s}}$ and the component normal up vector $\hat{\text{n}}$. The final power output equation is calculated as follows:

$$W_{\mathrm{out}}=F\times C_e\times C_p\times (\hat{\text{n}}\cdot \hat{\text{s}})\times A\times E$$

In this equation, $A$ is the area of the panel defined in squared meters, $E$ is the efficiency fraction of the solar panel (where typical efficiencies of solar panels are between 20 and 30%) and $C$ denotes the eclipsing visibility factor. $C_e$ is the eclipse factor caused by the celestial bodies blocking the sun, where $1$ would be perfect visibility and $0$ is entirely in eclipse. $C_p$ is the panel eclipse factor. This is calculated from an external integration such as Unreal and uses raycasts to determine if part of the spacecraft is blocking the solar panel’s area. Without Unreal, this value defaults to $1$.

The solar flux and eclipse data are pulled from the solar flux and eclipse message on the spacecraft. This is automatically fetched and added to the panel’s software definition. The efficiency can also be modelled to degrade over time, using a component error model. If the albedo model is applied to the orbiting body, and the spacecraft has been set up to read albedo data, then the total flux $F$ can be summed to be:

$$F=F_{\odot }+F_e(\hat{\text{n}}\cdot \hat{\text{e}})$$

where $\hat{\text{n}}$ is the component normal up vector, $\hat{\text{e}}$ is the earth direction vector, $F_{\odot }$ is the solar flux at that location and $F_e$ is the albedo value at the spacecraft’s location in orbit.

A solar panel degradation model can be added which degrades the efficiency of the solar panel over time. When configured, this is measured in a % per year, where it is relative to the 100% efficiency model.

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Assumptions/Limitations

• By default, no self-shadowing is assumed on the solar panel unless otherwise updated, which requires a visualization product.
• Additional sources of lighting (such as starlight or thermal models) do not contribute to the solar panel’s power output.
• Solar panels are defined as cellular units and cannot be broken down further. As such, the entire panel is treated as a uniform system, with sub-cells treated as parallel units without obstruction.