Improving the Reliability of a CubeSat Power System by Combining Small-Sized Monocrystalline Cells With Triple-Junction Solar Cells

Electrical Power System (EPS) failures are well-known challenges for small satellites, particularly CubeSats. These failures can arise from various causes, including short circuits, solar cell degradation, battery malfunctions, and harness failures. Due to their limited power resources, any negative impact on the estimated power generation can significantly hinder a CubeSat’s ability to achieve its mission objectives. These limitations are further exacerbated by strict constraints on volume and mass inherent to CubeSat platforms. In this paper, the feasibility of using small-sized monocrystalline solar cells alongside conventional triple-junction solar cells is investigated as a means to enhance EPS reliability. The focus is on mitigating the risk of complete satellite failure caused by the loss of a standard 8 cm×4 cm triple-junction solar cell. Additionally, the small-sized monocrystalline solar cells could potentially replace triple-junction solar cells when the satellite operates in a low-power mode, such as with beacons deactivated and in receive-only mode. Small-sized monocystalline solar cells alone generate 780mWh of power for a 1U CubeSat, which is sufficient to operate a CubeSat in receive-only mode, providing a cost-effective and reliable alternative for low-power missions.We analyzed the reliability of small-sized monocrystalline cells in the CURTIS and MicroOrbiter-1 CubeSats through a series of tests, including functional testing at room temperature, environmental testing (thermal and vibration), and assembly testing. Their reliability has been verified during missions lasting almost five months in orbit. A key challenge in adding a small-sized monocrystalline solar cell arises from spatial limitations, with the remaining space after installing the triple-junction solar cell being utilized by other satellite components. The issue of spatial limitations in the external panel surface is also studied in this paper.