Uncrewed Systems Technology 048 | Kodiak Driver | 5G focus | Tiburon USV | Skypersonic Skycopter and Skyrover | CES 2023 | Limbach L 2400 DX and L 550 EFG | NXInnovation NX 100 Enviro | Solar power focus | Protegimus Protection

106 andmany other factors affecting the shape and composition of the panel. Finer detail can then be derived. For example, data on a vehicle’s bus voltage requirement directly informs the electrical design of the solar cells, particularly howmany cells need to be connected together in series or parallel to build up to that voltage, while still meeting the geometrical requirements as defined by the properties of the craft’s body. By extension, that affects the manufacturing process, as the deposition timings, angles and material selections must be changed accordingly. Panel manufacturers can then experiment with prototypes or samples of the requested material, for instance small pieces or strings of it to show prospective customers what they would receive from larger versions. It can then be tested to evaluate how it will perform under the most severe conditions it might experience over its lifetime. Some of the steps that PV panels and samples are put through will seem familiar, such as thermal cycling from -50 to +60 o C to simulate the temperatures in the stratosphere, followed by inspecting the adhesives, interconnection points and the cells themselves for damage, as well as some power cycles to see how general performance has been affected. The cells will also undergo deflection and deformation, potentially while integrated onwing structures similar to those the customer wants to use, to predict how their performance and lifetime could be affected by themechanical aspects of the platformand operating environment. Beyond these though, solar panel testing procedures and equipment can be quite unique. Electroluminescence, for one, is an important tool for gauging physical damage to solar cells: by forward-biasing the cells, with visible red or IR light for example, they can be made to luminesce like an LED. Some solar manufacturers will therefore ‘light up’ their cells, and using an HD or IR camera they can closely measure the impact of damage on the cells’ photovoltaic performance. Also, directly measuring the solar conversion efficiency, absorptance and other factors relating to the transmission of light through a cell can be performed using sunlight simulators, using lamps that can be controlled to emit different portions and wavelengths of the solar spectrum, unlike sunlight, which changes constantly during the year. Naturally that also gives the ability to blast cells with UV light to gauge the survivability of different panel layers at higher altitudes and orbits. Other environmental survivability tests might then follow depending on the exact use case, such as damp heat testing to gauge humidity resistance if the uncrewed vehicle is to operate in such areas. Ancillary systems Work is also ongoing in power management and controller systems. These are key to collecting and distributing power, and therefore towards getting as much current and efficiency from the panels as possible. While solar cells have varying relationships and architectures with regard to controllers, inverters, grids and other load-relevant systems, MPPT (maximumpower point tracking) controllers are emerging as a popular energy management and extraction device among USVs in particular, for their ability to adjust impedance levels and optimise the power transfer efficiency fromcell to battery. Currently, bus voltages for uncrewed vehicles tend to range from 12 to 100 V, and many MPPT controllers are available for such voltages. But as time goes by and advances in e-mobility increasingly filter through, UAVs and USVs operating on 400-800 V are likely to become more and more common, especially in mapping and intelligence missions which come laden with Lidars, cameras and other power- hungry electronics. Then there are self-driving road vehicles, with solar-electric driverless cars and trucks likely to become prominent as awareness of thin-film, low- February/March 2023 | Uncrewed Systems Technology One company has included a printing machine for perovskites in its pilot flexible solar film production facility (Courtesy of Power Roll) Dual-junction perovskite-silicon cells are achieving 30% efficiency in lab conditions, and could therefore become an abundant, highly efficient solar product in the future (Courtesy of Power Roll)