HelioSpec uses multiple drones (a "swarm") equipped with cameras and sensors to efficiently inspect large photovoltaic (PV) solar sites. The drones can autonomously follow pre-programmed flight paths, communicate with each other, and capture high-resolution imagery and data. Operators can control multiple drones simultaneously and processed data is transferred to the cloud. HelioSpec also manages drone pilot training, regulatory compliance, and provides inspection services on a pay-per-use basis to reduce capital costs for customers. UAV inspection allows sites to be scanned quickly from optimal angles to diagnose various PV system errors and potential problems.