This system began each day performing within expectations. As the day continued, its output would slowly flatten out until there was clear underperformance. This behaviour was at its worst in peak summer conditions. During the middle of the day we were at about half the expected performance, with the same generation curve repeating itself across multiple days. The repeatability we saw here significantly narrowed down the possibilities. No one-off interruptions, no long-term string failures. The most likely culprits were a heavy export limit or inverter overheating.
Fortunately, Diagno does more than simply look at underperformance. Our system identified that inverter temperatures were reaching above 80 degrees Celsius. Textbook inverter overheating.
Turning a fault into maintenance
At this point, Diagno had flagged the clear underperformance and it was now time to confirm the issue. Instead of the asset manager receiving a generic overtemperature alarm, our diagnostic offered them a practical course of action: inspect and clean the ventilation channels and external fans. Dispatch a technician if the error still persisted.
The asset manager chose to arrange an inspection. After removing the inverter cover, the technician discovered the top-right cooling fan wasn’t spinning. It would turn if manually spun, but nothing could get it to move on its own. A clear failure. While they were there, they also cleared out dust and debris that had collected in the inverter grille.
The actual fix necessitated a second visit with a replacement fan. The technician completed the reinstallation and testing; Diagno confirmed that the inverter was now performing exactly as it should be. Our overheating inverter was no longer overheating at all.
“Minor” component failures create major underperformance
A cooling fan is a small part of a complex system. Any failed component warrants a replacement, but in this case the impact of its failure compounds. An overheating inverter gets the hottest during the sunniest parts of the day – which also happen to be when a typical solar installation is producing the most energy. The inverter prevents itself from further component damage by ‘derating’. It ramps down its power production to reduce the heat it’s producing.
If someone doesn’t have a close eye on the system the behaviour of the inverter could be mistaken for something else, like an export limit. Losses are compounded during the most productive time of the day.
The value of true performance monitoring comes from distilling persistent patterns from weather and noise, giving real advice on fixing the problem and pointing the technician in the right direction to save time on site. In this case, the loop was closed. The platform identified the issue, the technician confirmed the problem, and the platform confirmed the fix did what it should. If this system runs into another issue, Diagno is ready to call it out.
