The satellites small size and power needs require the use of the most efficient solar cells on the market. GaAs based solar cells have the potential to reach very high efficiencies. The triple junction Solar cell assemblies (SCA’s) used on SwissCube have a maximum efficiency of 25% (100µm coverglass included). They are soldered on printed circuit boards by using a process of screen printing developed at the Space Center of EPFL. The average power generated by the satellite during the daylight period of its polar orbit is approx 1.5W.
Two 1.2 ampere-hour lithium-Ion Polymer batteries from VARTA are used for the mission. Their major advantage is a high energy density.
The architecture has been essentially driven by the following principles:
- Provide a low voltage regulated DC bus
- Control the bus voltage with an analog circuitry
- Be able to deploy antennas and emit a beacon message without using a microcontroller
- Minimize the power loss usually associated to voltage levels conversion and protections
- Try to keep a high reliability even when using COTS components (hard selection, redundancy)
- Take advantage of very low consumption devices to reach the sum of functionalities required by the mission.