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MPPT solar charger manual

8. Troubleshooting

In this section:

Refer to this chapter for addressing any unforeseen behaviour of the solar charger. Start by reviewing the common issues listed here during troubleshooting.

If the problem persists or requires technical assistance, contact the point of purchase – the Victron Energy dealer or distributor. If unsure whom to reach or unaware of the point of purchase, visit the Victron Energy Support webpage for guidance.

8.1. Solar charger is damaged

Before proceeding with troubleshooting, it is important to inspect the solar charger for any visible damage. Please note that damage to the solar charger is typically not covered by warranty.

By conducting this initial visual inspection, you can identify any visible damage that may impact the functionality of the solar charger:

Visual inspection

Step 1

Examine the solar charger for any signs of mechanical damage to the housing or electrical terminals. Please be aware that this type of damage is not covered by warranty.

Step 2

Inspect the electrical terminals of the solar charger for signs of burning or melting. This type of damage is often caused by loose electrical connections, the use of rigid core cables, or exceeding the MC4 terminal current ratings. Please be aware that this damage is not covered by warranty. Refer to chapter PV connections burned or melted for more information.

Step 3

Look for any indications of water damage or corrosion on the solar charger, especially around the electrical connection area. It is important to note that such damage is not covered by warranty.

8.4. Solar charger is externally controlled

Managed batteries or an inverter/charger with an external control system (e.g., ESS system) can govern the solar charger via a GX device. The external system determines charging permissions and sets the charge voltage and currents.

When external control is active, it is visible on both the VictronConnect app and the GX device. This is normal behaviour and is not a fault.


The VictronConnect app indicates that the charger is externally controlled.

8.5. Batteries are not charged

This chapter explains scenarios where the charger is active, but the batteries are not charging. In such cases, the VictronConnect app will show the charger as active with the correct charge voltage, but the charge current will be at zero or very close to zero.

There are several reasons why this can happen, namely:
  • The battery is fully charged, and no further current is required. This is normal behaviour and is not a fault. Refer to the Battery is full chapter for more details.

  • Reverse PV polarity. Refer to the Reverse PV polarity subchapter for more details.

  • PV voltage is too high. Refer to the PV voltage too high subchapter for more details.

  • Reverse battery polarity. Refer to the Reverse battery polarity subchapter for more details.

  • The solar charger is disconnected from the battery, possibly due to cable, fuse, or circuit breaker issues. Refer to the Battery not connected subchapter for more details.

  • Incorrect charger configuration, e.g., low charge voltage or current setting. Refer to the Battery settings too low subchapter for more details.

  • The charger is externally controlled (ESS or DVCC), which is normal and not a fault. Refer to the Solar charger externally controlled chapter for more details.Solar charger externally controlled

  • The temperature-compensated charging feature is active, and the battery temperature is too high, or the feature is misconfigured. Refer to the Wrong temperature compensation setting chapter for more details.Wrong temperature compensation setting


The VictronConnect app shows a close to zero charge current.

8.5.1. Battery is full

Once the battery is full, the solar charger will stop or significantly reduce its charge current. This is especially evident when DC loads are not drawing power from the battery. It is important to note that this behaviour is normal and not a fault.

To determine the battery's state of charge (SoC), check the battery monitor (if available) or inspect the charge stage indicated by the solar charger. During the daily charge cycle, the solar cycle progresses through the following stages:

  1. Bulk stage: 0-80% SoC.

  2. Absorption stage 80-100% SoC.

  3. Float stage: 100% SoC.

Be aware that the solar charger may detect the battery as fully charged when it's not. This happens if the charge voltages are set too low, causing the charger to switch from absorption to float stage prematurely. Refer to the Battery settings too low chapter.Battery settings too low

8.5.2. Battery not connected

To ensure proper battery charging, a correct connection to the battery is crucial.

Be aware that that if the solar charger operates without a battery, it may seem connected, showing battery voltage and charge stage in the VictronConnect app, but the charge current will be negligible or zero.

Potential reasons for a disconnected battery:
  • Loose or missing battery cables.

  • Loose cable connections.

  • Poorly crimped cable terminals.

  • A blown (or missing) fuse in the battery supply cable.

  • Open (or faulty) circuit breaker in the battery supply cable.

  • Incorrectly wired battery cables.

Battery voltage check

Step 1

Use the VictronConnect app, a connected display or a GX device to read the solar charger battery voltage. Alternatively, use a multimeter to measure the battery voltage at the terminals of the solar charger.


Step 2

Use a multimeter to measure the voltage at the battery terminals.


Step 3

Compare the two voltages.

Step 4

In case of a voltage difference, investigate the reason behind it by tracing the path from the solar charger to the battery to identify the cause.

  • Check and confirm that all cabling is accurately connected and that there are no wiring errors.

  • Inspect the cable connections for tightness while keeping the maximum torque levels in mind.

  • Verify the correct crimping of all cable lugs or terminals.

  • Check the fuses and circuit breakers.


Should you come across a blown fuse, make sure to check the correct wiring of the battery polarity before replacing it. Refer to the Reverse battery polarity chapter.

8.5.3. Reverse battery polarity

Reverse polarity occurs when the positive and negative battery cables are accidentally swapped. This means the negative battery terminal connects to the positive solar charger terminal, and the positive battery terminal connects to the negative solar charger terminal.


Examples of correct and incorrect (reverse) battery polarity.


Be aware that a red or positively labelled cable may not necessarily indicate the cable is positive. A wiring or labelling mistake during the solar charger installation is possible.

Always double-check the battery polarity before reconnecting the battery wires to the solar charger.

Reverse battery polarity can potentially damage the solar charger, causing its internal fuse to blow for fail-safe protection. This fuse might blow before the external fuse in the battery cable. However, please note that the internal fuse is situated in a non-serviceable area, and it cannot be replaced or repaired. If this happens, the solar charger should be considered faulty.

The solar charger is not protected against reverse battery polarity, and any resulting damage is not covered under warranty.

8.5.4. Battery settings too low

If the solar charger's charge voltage and current are well below the manufacturer's recommended levels, the battery charging process may become inadequate or excessively slow. Incorrect configuration can be a contributing factor, including:

  • Setting the "Battery voltage" parameter too low.

  • Setting the ''Absorption voltage" and "Float voltage" parameters too low.

  • Setting the "Max charge current" parameter to zero or an excessively low value.


VictronConnect app, showing battery (system) voltage, charge current and charge voltages settings.

8.5.5. PV voltage too high

The PV voltage should always stay within the maximum rated limit of the solar charger, as indicated in its product name, type plate and Technical specifications. The solar charger can sustain damage based on the extent of the PV voltage height, and it's important to note that such damage is not covered by warranty.

Should the PV voltage exceed the maximum rated PV voltage, the solar charger will cease charging, showing an overvoltage error #33 with rapid blinking of the absorption and float LEDs. Charging resumes only when the PV voltage drops 5V below the rated maximum voltage.

During investigations into high voltage issues, it's essential to review the VictronConnect app, solar charger display, or GX device history. Check for the highest PV voltage recorded each day (Vmax) and past overvoltage warnings.

To avoid issues, check the open circuit voltage (Voc) rating of the PV array and ensure it is lower than the solar charger's maximum rated voltage. Use the MPPT sizing calculator on the solar charger product page. For PV arrays in cold climates or with night temperatures nearing or below 10°C, it's essential to consider possible increased output (more than its rated Voc). As a rule of thumb, maintain an additional 10% safety margin.


VictronConnect app error #33 indication on the status screen and history screen.

8.5.6. Reverse PV polarity

When the solar charger is installed within the published specifications, internal protection guards the PV input against reverse PV polarity, and no error is displayed in such cases.

To identify reverse PV voltage, watch for these indicators:
  • Absence of battery charging with the charge current remaining at zero.

  • Excessive heat generated by the solar charger.

  • PV voltage reading zero or close to zero.

To verify, use a multimeter to ensure that the positive PV cable is correctly connected to the positive PV terminal and the negative cable is connected to the negative PV terminal.



WARNING: Certain solar charger models may have PV voltages up to 250Vdc. Voltages exceeding 50V are generally considered dangerous. Only a qualified technician should handle dangerous voltages.

8.8. Solar charger not achieving full output

In addition to potential issues with the PV array, several other reasons can hinder the solar charger from reaching its full-rated output.

Reasons for the solar charger not reaching its full output:
  • The PV array is too small. If the PV array's power rating is less than the solar charger's nominal power rating, the solar charger cannot output more power than the connected solar array can provide.

  • The PV array is not reaching its maximum power rating. Refer to the PV yield lower than expected subchapter.

  • The PV array is a mix of different PV panel types or models. Only use solar panels that are of the same brand, type and model.

  • Do not use optimisers. Nearly all optimisers contain an MPPT or other tracking mechanisms, which will interfere with the MPPT algorithm in the solar charger.

  • The PV array is wrongly configured. For a detailed explanation of how to configure PV arrays and properly use MC4 splitters and MC4 combiners, see the "Solar panel" chapter in the Wiring Unlimited Book.

  • The solar charger's maximum PV output power is related to the battery voltage. Refer to the Maximum output power relates to battery voltage subchapter.

  • The solar charger's PV electric connections are burned or melted, or MC4 connectors have been insufficiently crimped. Refer to the PV connections burned or melted subchapter.

  • The solar charger temperature is above 40°C. Refer to the Temperature above 40°C subchapter.

  • The batteries are either full or nearly full, causing no further power to flow into them.

  • There may be an issue with the battery. Refer to the Batteries are not charged and Batteries are undercharged chapters.

8.8.1. PV yield lower than expected

If the PV yield is not meeting expectations, start by checking the solar charger history in the VictronConnect app. Verify the total maximum power (Pmax) for each day and compare it with the array power.

To determine the potential solar yield per day for a specific PV array size in a particular geographical location, utilise the MPPT sizing calculator on the solar charger product page.

List of reasons why the PV array may generate less power than expected:
  • Low sun angle (morning or evening) or seasonal differences.

  • Cloud cover or adverse weather conditions.

  • Shading from trees or buildings.

  • Dirty solar panels.

  • Incorrect orientation or inclination of the solar panels.

  • Broken or faulty solar panels.

  • Issues with wiring, fuses, circuit breakers, or there is a cable voltage drop.

  • Incorrect usage or malfunctioning splitters or combiners.

  • Part of the PV array is not functioning correctly.

  • The PV array is too small for the desired output.

  • Mistakes in solar array configuration.

  • The batteries may be too small or aging, resulting in a reduced capacity.


VictronConnect app history Pmax reading.

8.8.2. Maximum output power relates to battery voltage

The solar charger's output current is limited to its rated current, resulting in varying output power depending on the battery's voltage.

For instance:

In a 75/15 solar charger with a 15A output current rating, the power going into the battery will differ for a 12V battery and a 24V battery.

  • For a 12V battery, this is 15A x 12V = 180W.

  • For a 24V battery, this is 15A x 24V = 360W.

Thus, even though a 360W panel is connected to the solar charger, the output power into a 12V battery will be less than when connected to a 24V battery.


Example of differences in output power at different battery voltages

8.8.3. Temperature above 40°C

The solar charger operates up to 60°C, with full-rated output maintained up to 40°C. Above 40°C, the output will derate, reducing output power.

For efficient performance, consider the solar charger's mounting arrangement. Mount it vertically with terminals facing downwards to dissipate heat effectively. In closed enclosures, like cabinets, ensure proper airflow with mounted vents to allow cold air in and hot air out. In extremely high-temperature environments, mechanical air extraction or air conditioning may be necessary to maintain optimal performance.

8.8.4. PV connections burned or melted

Burned or melted PV cables or connections are not covered under warranty. This can occur due to the following reasons:

  • Loose screw connections.

  • Using cables with rigid core wire or rigid strands.

  • Soldering the core wire ends of the cables.

  • Using thin cables may result in higher currents when the PV voltage is lower. Refer to the Wiring Unlimited book for more information.

  • Inserting cable insulation too deeply into the connector.

  • Exceeding 30A per MC4 connector pair.

  • Incorrectly crimping MC4 connectors.

  • Using low-quality MC4 connectors.

8.10. Miscellaneous issues

This chapter describes issues that were not covered in the previous troubleshooting chapter.

8.10.1. Unable to operate as a DC-DC charger or power supply

Avoid using the solar charger as a DC-DC charger (e.g., to charge a 12V battery from a 24V battery bank). Connecting a battery to the PV terminals under certain operational conditions can damage the solar charger, which is not covered by the warranty. Instead, use a dedicated DC-DC charger or converter. Check our DC-DC converter product page for a complete product range.

Also, refrain from using the solar charger as a power supply without batteries connected. Although this operation won't harm the solar charger, it might not support all types of loads. Some loads may function, while others may not, particularly at low load power, where the solar charger's response might be too slow to maintain a constant voltage. Please note that support is not provided for such situations.

8.10.2. Interrupted firmware update

An interrupted firmware update is recoverable and there is no need to worry. Simply attempt to update the firmware once more.

8.10.3. Ground current

If a ground current is detected in the system during normal operation, take the following steps:

  • First, thoroughly inspect all the equipment connected to the system and check for any ground faults.

  • Next, verify the number of connections to ground in the system. Ideally, there should be only one point in the system connected to the ground, which should be at the battery.

  • For more information on system grounding, see the "System grounding" chapter in the Wiring Unlimited book.

Note that the solar charger is non-isolated and the minus of the PV input is at the same potential as the minus of the battery output.

8.11. Error code overview

The error codes in the following subchapters are potentially displayed in the VictronConnect app, on a remote display or a connected GX device. For the most up-to-date error overview, see this link:

Furthermore, the solar charger utilises specific LED indications to signal particular errors. For an overview of these LED codes, please refer to the Victron Toolkit app.

8.11.1. Error 1 - Battery temperature too high

This error will auto-reset after the battery temperature has dropped. The solar charger will stop charging to prevent damaging the battery. The battery temperature can be received by an external sensor (like Smart Battery Sense or BMV) or measured by the charger when this feature is available.

8.11.2. Error 2 - Battery voltage too high

This error will auto-reset after the battery voltage has dropped. This error can be due to other charging equipment connected to the battery or a fault in the solar charger.

This error can also occur if the battery voltage (12, 24, 48V) is set to a lower voltage than the connected battery.

8.11.3. Error 17 - Solar charger overheated despite reduced output current

This error will auto-reset after the solar charger has cooled down. Check the ambient temperature and check for obstructions near the heat sink.

8.11.4. Error 18 - Solar charger over-current

This error will auto-reset. If the error does not auto-reset, disconnect the solar charger from all power sources, wait 3 minutes, and reconnect so it will power up again.

Possible causes for an over-current on the battery terminals:
  • Switching on/off a very large load on the battery side.

  • Sudden change in irradiance is causing a temporary over-power in the solar charger.

  • Overload of the inverter ac output.

Possible solutions:
  • If possible, provide adequate cooling for the unit. A cooler unit can handle more current.

  • Reduce the load on the inverter.

  • Charge the battery before using the inverter. At higher battery voltages, the same amount of power requires less current.

8.11.5. Error 20 - Maximum bulk time exceeded

The maximum bulk time protection was a feature when the solar chargers were newly released in 2015 (or prior). This feature has now been removed.

If you see this error, update the solar charger to the latest firmware. If, after the update, you still see this error, then perform a "reset to factory defaults" and then reconfigure the solar charger.

8.11.6. Error 21 - Current sensor issue

If you see this error, update the solar charger to the latest firmware. If, after the update, you still see this error, then perform a "reset to factory defaults" and then reconfigure the solar charger.

Disconnect all wires and then reconnect all wires to force the solar charger to restart. Also, make sure the minus on the solar charger (PV negative and battery negative) is not bypassing the solar charger.

This error will not auto-reset.

If the error remains, please contact your dealer or distributor, as there might be a hardware defect.

8.11.7. Error 26 - Terminal overheated

Power terminals overheated, check the wiring, including the wiring type and type of strands, and/or fasten bolts if possible.

This error will auto-reset.

8.11.8. Error 28 - Power stage issue

This error will not auto-reset.

Disconnect all wires, and then reconnect all wires. If the error persists, the charger is probably faulty.

Note that this error was introduced in v1.36. So when doing an update, it might look like the firmware update caused this issue; but it doesn't. The solar charger was then already not performing 100% before the update; updating to v1.36 or later merely made the issue more visible. The unit needs to be replaced.

8.11.9. Error 33 - PV over voltage

This error will auto-reset after the PV voltage has dropped to a safe limit.

This error is an indication that the PV array configuration with regard to open-circuit voltage is critical for this charger. Check configuration, and if required, re-organise panels.

For more information, refer to the PV voltage too high chapter.

8.11.10. Error 38, 39 - PV Input shutdown

When these errors show, the PV Input is internally shorted to protect the battery from overcharging. Prior to any other troubleshooting, make sure to update to the latest firmware version.

Possible reasons for this error to occur:
  • The "Battery voltage" parameter (12/24/36/48V) is set incorrectly. Use the VictronConnect app to set the correct "Battery voltage" parameter.

  • Another device is connected to the battery, configured to a higher voltage. For example, an inverter/charger is configured to equalise at 17 Volts, while this is not configured in the solar charger.

Error recovery:
  • Error 38: First, disconnect the solar panels and then disconnect the battery. Wait for 3 minutes, then first reconnect the battery and then the panels.

  • Error 39: The charger will automatically resume operation once the battery voltage drops below its maximum voltage setting (normally Equalisation or Absorption voltages). It can also take a minute to reset the fault.

  • If the error persists, the solar charger is probably faulty.

8.11.11. Error 40 - PV Input failed to shutdown

If the solar charger is unable to turn off the PV input, it will go into a safe mode in order to protect the battery from over-charging or having a high voltage on the battery terminals. In order to do that, the solar charger will stop charging and disconnect its own output. The solar charger will become faulty.

8.11.12. Error 80 to 88 - PV Input shutdown

When these errors show, the PV Input is internally shorted in order to protect the battery from over-charging.

Prior to any other troubleshooting, make sure to update to the latest firmware version.

Possible reasons for this error to occur:
  • The "Battery voltage" (12, 24, 36 or 48V) parameter is set incorrectly. Use the VictronConnect app to set it to the correct battery voltage.

  • Another device is connected to the battery with a higher charge voltage configuration. For instance, a MultiPlus is configured to equalise at 17V, while the solar charger has not been configured for equalise charging.

Error recovery:
  • Ensure that the solar charger is running the latest firmware.

  • Errors 80 to 83: First, disconnect the solar panels, then disconnect the battery and then follow the procedure as described in the ??? chapter.

  • Errors 84 to 87: First, disconnect the solar panels and disconnect the battery. Wait for 3 minutes, then first reconnect the battery and then reconnect the panels.

  • If the error persists, the solar charger is probably faulty.

8.11.13. Error 116 - Calibration data lost

If the unit does not work and error 116 pops up as the active error, the unit is faulty. Contact your dealer for a replacement.

If the error is only present in the history data and the unit operates normally this error can be ignored safely. Explanation: when the units power up for the very first time in the factory, it does not have calibration data and an error 116 is logged. Obviously, this should have been cleared, but in the beginning, units left the factory with this message still in the history data.

SmartSolar models (not the BlueSolar models): upgrading to v1.4x firmware is a one-way trip, you cannot go back to an older firmware version once you upgrade to v1.4x. Reverting to older firmware gives error 116 (calibration data lost), this can be fixed by re-installing the v1.4x firmware.

8.11.14. Error 117 - Incompatible firmware

This error indicates that a firmware update did not complete, so the device is only partially updated. Possible causes are: the device was out of range when updating over the air, a cable got disconnected or power was lost during the update session.

To fix this the update needs to be retried, download the correct firmware for your device from the Victron Professional Portal

When your GX device is connected to VRM, you can do a remote firmware update using this firmware file. You can do this via the VRM website or using the VRM tab in VictronConnect. VictronConnect can also be used together with the firmware file to update using a Bluetooth connection.

The procedure to add the file to VictronConnect and start the update is described here: 9. Firmware updates

8.11.15. Error 119 - Settings data lost

The charger cannot read its configuration and has stopped. This error will not auto-reset.

Perform the below procedure to get it working again:

Error recovery:
  • First, restore it to factory defaults. (top right in Victron Connect, click on the three dots).

  • Disconnect the solar charger from all power sources.

  • Wait 3 minutes, and power up again.

  • Reconfigure the charger.

  • Report this to your Victron dealer and ask for it to be escalated to Victron; as this error should never happen. Preferably include firmware version and any other specifics (VRM URL, VictronConnect screenshots or similar).