Review of unmanned ground vehicles for PV plant inspection

The growth of utility-scale solar power plants, which can now have more than a million PV modules, has created the need for automated monitoring and inspection technologies. Unmanned aerial vehicle (UAVs, or “drones”) have become widely used, especially for thermal infrared imaging, due to their falling cost, increasing technical capability, and ability to survey many modules quickly. However drones have certain limitations: they do not see the underside of PV arrays or balance-of-system equipment, it is difficult to hold a steady position for long- or repeated-exposure imaging, and operating permits can be onerous. In such cases unmanned ground vehicles (UGVs, or “robots”) can be advantageous for PV plant inspection. This paper reviews robot movement mechanisms (wheels, tracks and legs), types of PV faults for which they are suited, and their current status of use in commercial solar farms. Further, it examines typical obstacles to robot navigation in Australian solar farms. Key conclusions are that robots are likely to complement rather than replace drones for PV inspection, and are especially valuable for reducing fire risk by detecting hot-spots in electrical components.