The solar panels used to generate the power for transmission to the ground stations will be thin film solar panels, which currently return an efficiency of about 16.8 kilowatts per kilogram. Given that the power required for transmission dwarfs all other power requirements, except for the power for the ADACs, the necessary mass for the solar panels is easily calculated to be approximately 595,000 kg. However, degradation of the solar panels over time must also be taken into account. Assuming a 15% degradation over the course of 5 years (a reasonable assumption for a satellite in LEO), the solar panel mass comes to about 700,000 kg. Every 5 years, approximately 105,000 kg of solar panels must be replaced to account for the degradation over time and maintain an acceptable level of power output. Replacing the solar panels frequently minimizes the replacement mass needed, and allows for further drops in costs of solar panels over time (in addition to drops in cost associated with increased production).
The power subsystem is also responsible for providing power (typically electrical) to all subsystems that need to be powered, and includes conditioning to appropriate levels. Solar panels are often used in conjunction with batteries for low Earth orbit (LEO) satellites, as it provides a reliable power source with no interruptions when both methods are used together. However, this satellite uses solar panels to provide large amounts of power to ground stations, making it unnecessary to use independent solar panels. Additionally, as the satellite is always in sunlight, batteries are unnecessary. Thus, the only consideration is power conditioning. A small level of incoming power from the solar panels will be diverted to the onboard power conditioner, which will in turn provide electrical power to other subsystems such as the onboard computer, command and data handling (CDH) subsystem, and ADACs.
