Pre-purchase PV Installation Assessment and Locating Defects

Case Overview

An organization was planning to take over a 1 MW photovoltaic installation. There were assumptions that the farm was not performing at the expected levels with indications of some disconnected strings. Unable to exactly locate the malfunctions and wanting to gain a complete overview of the site’s true condition, a detailed investigation was needed.

Case Facts

  • 1 MW solar installation
  • Site operating for more than 7 years
  • Thermal and RGB images collected within a 30min flight
  • Drone inspection performed in line with IEC TS 62446-3:2017 standards


Solar Spy performed a thorough aerial inspection of the solar farm, followed by a comprehensive analysis of the site’s performance. The evaluation was based on historical data and by running energy production simulations with the use of a digital twin of the installation. Solar Spy delivered a detailed report, revealing 12% underperformance due to anomalies, along with the defects’ locations, and a set of general recommendations on how to proceed in such cases.


  • Several issues were revealed with their exact location: including offline strings, active bypass diodes, hotspots, dirt, and vegetation.
  • The report proved that the identified defects were greatly impacting energy production.
  • The delivered data allowed to undertake appropriate service tasks and significantly enhance the farm’s operations.