Inspecting 80,760 solar panels? Use drones
by Robert Yang | July 24, 2021
It’s easier and cheaper to maintain something than to fix it. This is why we get oil changes for our car or why we try to eat healthy, take supplements and exercise. The same concept can also be applied to our electric grid. It’s also why Hawaiian Electric’s Power Supply team requested help from certified drone pilots in our Unmanned Aircraft Systems (UAS) program to perform preventative maintenance inspections for the company’s West Loch Solar facility on Oahu.
The 102-acre, 20-megawatt solar facility went online in 2019. There are 80,760 solar panels mounted in an open field that takes in the sun’s rays and becomes renewable energy to power homes and businesses. Before unmanned aircraft systems (UAS), or drones, were introduced to our company in 2016, a technician would inspect solar farm panels by physically testing each circuit with a meter. From there, they would have to narrow down which panels were faulty based on the readings from the meter. Can you imagine how long it would take an inspector to do that for West Loch Solar? I’ve walked through that facility — and it’s huge!
Luckily for us and our customers, drones can reduce the work, risks, and costs. Hawaiian Electric UAS pilots programmed drones to fly autonomously in a designated airspace along the solar array using a mapping pattern. Every two seconds, it captured a thermal image of the solar panels from above. The images were sent to a third-party vendor who used a computer to analyze them. They looked for “hot spots” or areas with clustered orange dots on the image. This indicates a cell has gone bad and is overheating because it is dissipating power rather than moving it along through the system. Overheating cells can cause cracks to the module, causing the whole panel to eventually fail.
The inspection took two weeks to complete. Challenges included getting permission to occupy the airspace and managing battery run-time of the drones. The land that houses West Loch Solar is leased to Hawaiian Electric by the Navy and sits between Daniel K. Inouye Airport and Kalaeloa Airport so our pilots needed permission from the Navy and Federal Aviation Administration to conduct their inspections. Also, DJI (the manufacturer of the drone) places digital locks on drones near restricted zones (areas near airports) for safety reasons so we also needed permission to adjust these settings. Each drone uses two batteries per flight and averages about 40 minutes in flight time. A lot of time was spent landing drones for battery changes because there was a lot of land to cover.
“Efficiency really drives this process. The inspection basically saves everyone a lot of money and time. It helps us cut costs on maintenance and we can quickly address problems before they come up,” said Cullen Chong, Hawaiian Electric UAS program manager.
It’s also a win for our customers too! When we operate more efficiently, those savings get passed on to customers. Generation facilities that run smoothly also minimize the risk of interruption to electrical service.
It’s exciting to see our company utilize high-tech drones to improve the efficiency of our processes.
Eleven hours of flight time and 40,000 images later, we received the results from this inspection. Based on the captured images seen, everything appears to be working fine as intended.
Robert Yang is a digital communications and social media specialist at Hawaiian Electric Company.
