Inverter Diagnostics3 min read
Solar inverter not starting? Details to check and report
Distinguish between a blank display, no solar generation, and a recurring fault code so a technician can scope the right assessment.
1. Distinguish blank display vs. active fault code
A completely dark LCD with no fan spin when grid and battery are present typically points to an internal auxiliary SMPS failure, blown DC input fuse, or tripped external DC breaker. By contrast, an active fault number or warning icon indicates the control board is powered and actively protecting the hardware.
2. Safe external observations to record
Never open the inverter enclosure yourself, as DC bus capacitors hold lethal voltage even after disconnects are switched off. Instead, record clear observations from the exterior:
- Exact model sticker and kW rating on the side of the unit
- Exact fault code (e.g., F09, 04, 51) and whether it appears immediately or only under load
- Status of the external AC breaker, PV DC isolator, and battery breaker
- Whether any burning smell, breaker trip, or grid surge occurred beforehand