Fronius Inverter Support — State Codes, Isolation Faults & Aging Capacitors
One of the UK's most established string inverter brands — Primo and Symo units installed from 2012. State codes, isolation faults, grid disconnection, aging capacitors — we diagnose Fronius systems from Solar.web data and event logs. Remote-first. Independent from Fronius and your installer.
State code error, isolation fault, Solar.web offline — we diagnose Fronius systems remotely in a single session.
Book a Remote Diagnostic — from £75 → See the Solar Health PlanSafety: do not open inverter enclosures. If the inverter displays an isolation fault, do not repeatedly restart — this does not fix the fault.
Common Fronius problems we diagnose
Every fault below has a proven diagnostic path. Click through for the specific page or book a diagnostic if you're unsure.
Fronius displays state codes on the LED display and in Solar.web event log. Format xxx.yyy indicates fault category and specific event. Common codes: 102.x (grid fault), 401.x (isolation fault), temperature events. Diagnosis requires checking the exact code and timestamp.
See diagnostic guide →Inverter powered but generating zero power. Could be a DC string fault, isolator not closed, or protection trip not cleared. Check Solar.web historical data and string-level metrics to identify the fault pattern.
See diagnostic guide →Inverter generating below expected output for conditions. May indicate soiled panels, partial string shading, or internal component degradation. Solar.web data analysis reveals the loss pattern over time.
See diagnostic guide →Inverter has measured a drop in DC-to-earth resistance below the safe threshold. Common causes: water ingress into MC4 connectors, cracked cable insulation from UV, or failed panel junction box. Do not repeatedly restart — this is a genuine safety fault requiring investigation.
See diagnostic guide →AC voltage or frequency at grid connection has exceeded safe limits. Common in solar-dense streets where export raises local grid voltage. May clear automatically or require export limit configuration and DNO notification.
See diagnostic guide →Age-related component failure common in Fronius units from 2012–2018. Causes intermittent shutdowns, output reduction, and eventually complete failure. Capacitor replacement is viable on well-maintained units under 10 years old.
See diagnostic guide →Portal shows no data while inverter is generating. Caused by Fronius Datamanager communication card losing internet connection. Router change, WiFi password update, or broadband failure. Inverter continues to operate normally.
See diagnostic guide →Fronius Datamanager card unable to find WiFi network. Requires reconfiguration via the Datamanager setup wizard (accessible at inverter IP address on local network) or Fronius Solar.web app Bluetooth setup.
See diagnostic guide →Fronius state code index
Seeing an error code in Solar.web or on the inverter display? Our full Fronius state code index explains what each code means, common causes, and safe next steps.
What we do for Fronius owners
Remote Fronius Diagnostic
We review Solar.web data, inverter settings, and fault history to identify the exact fault without a site visit.
Fronius System Recovery
Installer gone bust, Solar.web access lost, or monitoring never set up correctly? We recover access and rebuild documentation.
On-Site Fronius Repair
Isolation fault investigation, DC cable fault location, capacitor replacement assessment, component repair. Targeted visit — no guesswork on arrival.
Fronius datasheets, manuals & warranty PDFs
Download datasheets, installation manuals and warranty documents for Fronius Symo inverters and battery systems. Self-hosted and always current.
Fronius fault code index
Seeing an error code on your Fronius inverter? Our fault code index explains what each code means, common causes, and safe next steps.
About Fronius systems — what you need to know
Fronius is one of the UK's most established solar inverter manufacturers. The Primo (1–15kW single-phase) and Symo (3–25kW three-phase) ranges have been installed since 2012, making them some of the oldest string inverters still in widespread use. The legacy SnapINverter series (Galvo) from 2012–2018 is also still supported.
Fronius inverters are string inverters — no optimizers, whole-string MPPT. State codes (xxx.yyy format) are the standard fault language — the first three digits identify the fault category (102 for AC grid, 401 for isolation), decimal digits for specific events. Isolation faults are most serious — they indicate DC-to-earth resistance drop and trigger automatic shutdown for safety.
The Solar.web portal and app are powered by the Fronius Datamanager communication card. Many units from 2012–2018 are now 8–12 years old and approaching capacitor end-of-life. Capacitor degradation is the most common age-related failure causing intermittent shutdowns and output reduction. If you're searching for Fronius repair UK, Fronius state code, Fronius isolation fault, Fronius Solar.web offline, or Fronius capacitor replacement, STS provides independent diagnostic and repair support across the UK — not affiliated with Fronius.
Fronius questions answered
State codes appear on the inverter LED display or in Solar.web event log. Format xxx.yyy — first three digits identify fault category (102 = AC grid, 401 = isolation), decimal digits identify specific event. Find your code: in Solar.web go to Current Data > Inverter Status, or on inverter press button to scroll display. Note exact code and timestamp. See code decoder →
Isolation fault means inverter measured a drop in DC-to-earth resistance below safe threshold. Common causes: water ingress into MC4 connectors, cracked cable insulation from UV, or failed panel junction box. It's a genuine safety event — inverter shuts down to protect the grid. Do not repeatedly restart; this does not fix the fault and may make diagnosis harder. Isolate system and book an inspection.
If inverter is generating but Solar.web shows no data, the Fronius Datamanager communication card has lost internet connection. This happens after router changes, WiFi password updates, or broadband failures. Access Datamanager setup wizard by navigating to inverter's IP address on local network (found in router DHCP list), or use Fronius Solar.web app Bluetooth setup to reconnect.
Fronius SnapINverter (Galvo, Primo) units from 2012–2018 are now 6–12 years old. Capacitor degradation is most common age-related failure — causes intermittent shutdowns, output reduction, eventually complete failure. Capacitor replacement is viable and cost-effective on units less than around 10 years old if otherwise well-maintained. We assess repair-vs-replace decision remotely using Solar.web historical data.
STS supports all major inverter and battery brands — not just Fronius. If you have a mixed-brand system or are comparing options, visit the brand hub.
Browse all 19 brands →Ready to fix your Fronius system?
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