- Solar and energy
- Solar inverter
502
Fronius inverter event 502
Risk level
Critical
Stop using the equipment and contact a professional.
Urgency
Immediate
Quick answer
Fronius defines event 502 as: The inverter reports an insulation error on the solar modules. The useful next discriminator is the affected string, weather correlation and insulation trend. Preserve the event before any reset.
Safety first
What to do now
- Preserve the exact event context
Save event 502, timestamp, inverter model/serial, firmware, red-LED state, affected phase/string, power and weather before clearing anything.
- Collect one safe discriminator
Leave feed-in stopped. Record the named string and whether the event follows rain, dew, wind or a recent roof/cable intervention; do not touch DC connectors. Record the affected string, weather correlation and insulation trend; do not change multiple parameters or circuits at once.
- Respect the electrical stop point
A cleared event is not proof that insulation is safe. Recurrence, especially with weather, requires per-string measurements before reconnection.
What you must never do
- Do not attempt this professional task: Measured handoff for Fronius 502
What a technician must be able to justify
A technician is coming
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
Measured handoff for Fronius 502
What they doUnder the same weather conditions, isolate and measure each indicated string’s insulation resistance and voltages to PE, then inspect connectors, cable runs and modules before reconnecting.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- Solar and energy
- Brand
- Fronius
- Product type
- Solar inverter
Known code variants
- 502 Bad Gateway
- 502 Fehlerhaftes Gateway
- 502 Gateway non valido
- 502 Puerta de enlace incorrecta
- Bosch 502 bici elettrica
- Bosch 502 bicicleta eléctrica
- Bosch 502 E-Bike
- Bosch 502 eBike
- Bosch 502 vélo électrique
- Bosch eBike code 502
- Bosch eBike error 502
- Bosch eBike Fehler 502
- Bosch eBike Fehlercode 502
- code Bosch eBike 502
- code erreur 502
- codice Bosch eBike 502
- código Bosch eBike 502
- erreur Bosch eBike 502
- error Bosch eBike 502
- errore Bosch eBike 502
- événement Fronius 502
- evento Fronius 502
- Fronius Ereignis 502
- Fronius event 502
- Fronius inverter 502
- Fronius Symo / Eco 502
- Fronius Wechselrichter 502
- HTTP 502
- HTTP status 502
- inversor Fronius 502
- inverter Fronius 502
- onduleur Fronius 502
- status code 502
What it means
Official meaning: The inverter reports an insulation error on the solar modules. Decision boundary: capture the affected string, weather correlation and insulation trend. Under the same weather conditions, isolate and measure each indicated string’s insulation resistance and voltages to PE, then inspect connectors, cable runs and modules before reconnecting.
Warnings and stop conditions
- Criticalsource verified
PV strings retain hazardous DC voltage in daylight even when the inverter is off. Do not unplug, test or handle strings or connectors.
Evidence: Fronius Symo / Eco status diagnostics
Sources and technical references
- 1
Fronius Symo / Eco status diagnostics
Fronius International GmbH · 2025 · official_doc
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