Unmanned Systems Technology 008 | Alti Transition UAS | Ground control systems | Xponential 2016 report | Insitu Orbital N20 | UAVs | Solar power | Oceanology International 2016 report

79 of extra space, while the latter two can be very expensive. There is, however, another approach that is gaining momentum: solar power technology, which has been proven for decades in space and has improved dramatically over the years. The amount by which adding solar panels to a UAV can boost fight endurance depends greatly on the aircraft’s design and mission, but in most cases it can be an increase of 1.5-2.5x without any changes to the aircraft’s structure or electrical systems, and in cases where aircraft are optimised for the solar cells, increases of up to 4x are possible. The thin, lightweight and highly effcient solar cell technologies now available can offer immense benefts to fxed-wing UAVs. Capturing photons The solar cell works in several steps. The photons in sunlight strike the solar panel and are absorbed by semiconducting materials, causing electrons to be excited. Once excited, an electron can either dissipate the energy as heat and return to its orbital in an atom or travel through the cell until it reaches an electrode. Current fows through the material to cancel the potential difference and this current is then captured by the cell. In this way an array of solar cells converts solar energy into a usable amount of dc power. The traditional material for a solar cell is silicon which, while relatively inexpensive, is too heavy for UAVs. When the space industry was using silicon it had a certain dollar/Watt that it was used to working to, but using these silicon panels brought the burden of a great deal of mass and volume to the platform. Over time, the industry began to take a more integrated approach, looking at solar panels as part of the entire platform rather than an add-on, and it discovered that although it was more expensive to look at lighter, thinner solar panels it enabled many important technologies, such as better resolution of sensors, better data and longer fight durations. That realisation that solar can become more valuable when integrated into the overall design of a platform is now permeating through to the UAV sector. One solar cell manufacturer reports that although the industry was originally shocked at how much solar power cost as dollars/Watt, it is now warming to the Solar power | Focus Once the preserve of the military and satellites, solar power is becoming a viable tool for the burgeoning commercial UAV market, as Mark Venables explains Bright future Unmanned Systems Technology | June/July 2016