Seeing an error code on your Victron SmartSolar MPPT can be alarming, especially if it's stopping your solar panels from charging. This guide covers every error code your SmartSolar or BlueSolar MPPT might display, explains what causes each one, and provides step-by-step fixes.
Where to Find Error Codes
Error codes appear in several places:
- VictronConnect app — shown on the main status screen and in the history log
- VRM portal — visible in the device list and advanced tab (if connected via a GX device)
- GX device display — shown on the Cerbo GX, GX Touch, or Color Control GX
In VictronConnect, go to the History tab to see if error codes have occurred on previous days, even if the controller appears to be working normally now.
Error Code Reference Table
| Error | Name | Severity | Common Cause |
|---|---|---|---|
| Err 1 | Battery temperature too high | Warning | Ambient temperature or battery heat |
| Err 2 | Battery voltage too high | Critical | Battery voltage exceeds safe limit |
| Err 3 | Remote temperature sensor failure | Warning | Disconnected or faulty temp sensor |
| Err 4 | Remote temperature sensor failure | Warning | Disconnected or faulty temp sensor (battery) |
| Err 5 | Remote temperature sensor failure | Warning | Connection issue with external sensor |
| Err 6 | Remote battery voltage sense failure | Warning | VE.Smart voltage sense disconnected |
| Err 7 | Remote battery voltage sense failure | Warning | VE.Smart voltage sense out of range |
| Err 8 | Remote battery voltage sense failure | Warning | VE.Smart data not received |
| Err 17 | Controller overtemperature | Warning | Controller too hot, output reduced |
| Err 18 | Controller over-current | Warning | Current exceeded rated maximum |
| Err 20 | Maximum bulk time exceeded | Warning | Battery not accepting charge after max bulk time |
| Err 21 | Current sensor issue | Warning | Internal current measurement fault |
| Err 26 | Terminal overheated | Warning | Loose or corroded battery terminals |
| Err 28 | Power stage issue | Critical | Internal hardware problem |
| Err 33 | PV over-voltage | Critical | Solar panel voltage exceeded maximum input |
| Err 34 | PV over-current | Warning | PV current too high (rare, check wiring) |
| Err 38 | PV input shutdown (excess power) | Warning | Battery full, excess PV power |
| Err 39 | PV input shutdown | Warning | Inverter not consuming, battery full |
| Err 40 | PV input not available | Info | Panel disconnected or no sunlight |
| Err 116 | Calibration data lost | Critical | Factory calibration corrupted — contact Victron |
| Err 117 | Incompatible firmware | Warning | Firmware update failed or incompatible version |
| Err 119 | Settings data lost | Warning | User settings corrupted — reconfigure |
Most Common Errors and Fixes
Error 33: PV Over-Voltage
This is the most dangerous error. It means the voltage from your solar panels has exceeded the controller's maximum input voltage. This can permanently damage the MPPT.
Causes:
- Too many panels wired in series
- Cold weather increasing panel Voc beyond the rated STC value
- Wrong controller chosen for the panel configuration
Fix:
- Immediately disconnect the solar panels (disconnect PV first, then battery).
- Check the total Voc of your panel string. Apply a cold weather correction factor (add 10–15% for UK temperatures).
- If the corrected Voc exceeds your controller's voltage rating, you must either rewire panels (series to parallel, or reduce the number in series) or upgrade to a controller with a higher voltage class.
- If the error appeared only once on a very cold morning but your calculations are borderline, consider it a warning — upgrading the controller is strongly recommended.
Error 2: Battery Voltage Too High
The MPPT has detected that battery voltage is higher than its safe operating range.
Causes:
- Incorrect charge voltage settings (absorption voltage set too high)
- Another charger (shore power charger, alternator) pushing battery voltage up while the MPPT is also charging
- Failed battery cell causing voltage spikes
- Wrong system voltage selected (controller configured for 12V but connected to a 24V bank)
Fix:
- Check your charge voltage settings in VictronConnect. Ensure the battery preset matches your actual battery type.
- If you have multiple charge sources, verify they're all set to compatible voltages.
- Measure battery voltage with a multimeter. If it's abnormally high with all chargers disconnected, the battery may be faulty.
Error 17: Controller Overtemperature
The MPPT has reduced its charge current because the internal temperature is too high. This is a protective measure, not a failure.
Causes:
- Controller mounted in a poorly ventilated space
- High ambient temperature combined with high charge current
- Controller mounted on a surface that traps heat (directly on wood without airflow)
Fix:
- Ensure the controller has adequate ventilation. Victron recommends at least 10cm clearance above and below for airflow.
- Mount vertically with terminals at the bottom — heat rises naturally, which helps cooling.
- In hot environments, consider a larger controller model (which runs cooler at the same load) or adding a small 12V fan for active cooling.
Error 26: Terminal Overheated
The battery terminals on the MPPT are running hot. This is almost always a wiring problem.
Causes:
- Loose terminal connections
- Undersized cables (too thin for the charge current)
- Corroded or damaged cable lugs
Fix:
- Disconnect all cables and inspect the terminal screws, cable lugs, and conductor strands.
- Ensure cables are appropriately sized for the maximum charge current. For a 30A controller, use at least 6mm² cable. For a 50A+ controller, use 10mm² or thicker.
- Re-crimp or replace any damaged lugs. Tighten terminals to the torque specified in the Victron manual.
- Clean any corrosion from terminals and lugs before reconnecting.
Error 20: Maximum Bulk Time Exceeded
The controller has been in bulk charge for an unusually long time without reaching absorption voltage. This suggests the battery isn't accepting charge properly.
Causes:
- Battery is deeply discharged or degraded
- Battery bank is much larger than the solar array can charge in a day
- A large load is drawing power while the MPPT is trying to charge
Fix:
- Check battery health. For lead-acid batteries, measure individual cell voltages or perform a capacity test.
- Ensure loads aren't drawing more current than the solar array produces during the day.
- If the battery bank is very large relative to solar input, this error may be normal on short winter days — the MPPT simply runs out of sunlight before the battery reaches absorption voltage.
Errors That Require Professional Help
Error 28: Power Stage Issue
This indicates an internal hardware failure in the MPPT's power conversion circuitry. This is not user-fixable.
Action: Contact your Victron dealer for warranty support. Do not continue using the controller.
Error 116: Calibration Data Lost
Factory calibration data has been corrupted. The controller cannot operate safely without this data.
Action: Contact Victron directly. The unit typically needs to be returned for repair or replacement.
Preventing Errors
- Size your system correctly — use our MPPT sizing guide to ensure voltage and current limits are respected.
- Include cold weather margins — always calculate Voc with a temperature correction factor for your climate.
- Use appropriate cables — undersized cables cause heat problems that trigger Error 26 and reduce system efficiency.
- Ensure ventilation — mount the controller vertically in a well-ventilated location.
- Keep firmware updated — newer firmware versions improve error handling and may resolve false positives.
- Check history regularly — the VictronConnect history tab shows errors even if they were brief and self-cleared. Catching intermittent issues early prevents bigger problems later.
Summary
Most Victron MPPT error codes are caused by installation issues — wrong panel wiring, loose terminals, poor ventilation, or incorrect settings. Errors 33 (PV over-voltage) and 2 (battery voltage too high) are the most serious. Error 17 (overtemperature) is the most common in campervan installations and is usually solved with better mounting and ventilation. Check the VictronConnect history tab regularly to catch intermittent errors before they become persistent problems.
