Issue 55 Uncrewed Systems Technology Apr/May 2024 Sellafield’s UAV equipment l Applied EV Blanc Robot l Battery tech l Robotican’s Goshawk l UGVs l UAVHE RW1 rotary l Roboat UVD l Autopilots l Arkeocean UVD l UMEX 2024 l CycloTech UVD

14 Platform one Rollable perovskite photovoltaic (PV) solar cells are being tested in orbit to provide power for satellites and autonomous space systems (writes Nick Flaherty). Australia’s national science agency, CSIRO, has successfully launched the rollable, printed PV cells into space aboard Australia’s largest private satellite, Optimus-1, on Space X’s Transporter-10 mission. Working with Space Machines, the mission aims to explore the potential of printed, flexible solar cells as a reliable energy source for future space projects. These modules use a unique approach, where the cells are deployed with ribbons of titanium-nickel, a shape-memory alloy (SMA) that unrolls when it warms up. The flexible cells are less than a micron thick, the result of using a printed layer of metal halide perovskite material, rather than silicon or gallium arsenide (GaAs) on a plastic substrate with a thickness of 125 μm. This can reduce the manufacturing costs for a solar cell with a rollable form factor, with lower stowed volumes and a specific power that is 10 times greater than commercial, triple-junction GaAs solar cells, which are commonly used for space applications that have a specific power of under 0.5 W/g. This comes from using the lighter, thinner substrate and perovskite PV material, which has an energy conversion ratio of above 10%. The trained SMA produces a thermal activation force such that a 20 to 30 mm-wide SMA ribbon is sufficient to roll out a flexible, 300 mm-wide solarcell module on a 125 μm-thick plastic substrate. Less SMA material is required for the thinner substrates. The cells have shown a tolerance to high-energy proton (14 MeV) and electron (>1 MeV) radiation in the laboratory that is comparable with, or superior to, equivalent glass-based solar cells, and they are significantly less dependent on the angle-of-incidence of the light than GaAs cells. In-situ testing is providing information on the performance of the various types of perovskite cells as they orbit the planet. “Based on our research, we expect our printed, flexible solar cells will stand up to the effects of cosmic electron and gamma radiation, which can compromise the performance and integrity of traditional solar cells,” said Dr Anthony Chesman, renewable energy systems group leader at CSIRO. “We are also confident that these cells will outperform traditional cells in cases where sunlight hits them at non-optimal angles.” PV solar cells Space tests for rollable solar cells “CSIRO’s printed, flexible solar cells could provide a reliable, lightweight energy solution for future space operations and exploration,” said CSIRO’s space program director, Dr Kimberley Clayfield. “If the space-flight test reveals similar performance as we’ve shown in the lab, this technology offers significant advantages over traditional, silicon-based solar.” Eight mini-modules using two different printed, flexible solar cells made by CSIRO were attached to the surface of Optimus-1 to test performance in orbit, where temperatures vary from -80 C in the dark to +130 C in the light. April/May 2024 | Uncrewed Systems Technology Dr Anthony Chesman, renewable energy systems group leader at CSIRO