Common Inverter Error Codes: A Fault Reference Guide for Zimbabwe

When the power goes out, your Solar Inverter is your most valuable asset. Seeing a strange number or fault code on its display can be stressful, but understanding what it means is crucial. This comprehensive guide from Sona Solar Zimbabwe explains the most common Inverter Error Codes, helping you quickly diagnose issues and restore your system to reliable, uninterrupted power.

Trusted Choices for Reliable Installations
Learn how to maintain your Must, SRNE, and Sumry inverters for optimal performance and peace of mind.

Error 01: Fan is locked when inverter is off
The inverter's cooling fan is obstructed or has failed. A foreign object may be blocking the blades, or the fan motor may have seized.

Error 02: Inverter transformer over temperature
The transformer has exceeded its safe operating temperature. This is a common issue during periods of heavy usage and high ambient temperatures. Check for poor ventilation or a malfunctioning cooling fan.

Error 03: Battery voltage is too high
The DC voltage from your battery bank is higher than the inverter's limit, often due to incorrect battery settings or a faulty charging source.

Error 04: Battery voltage is too low
A very common fault during extended load shedding. The battery voltage has dropped below the minimum level because the batteries are depleted. They need to be recharged by solar or the grid.

Error 05: Output short circuited
A critical safety shutdown caused by faulty wiring, a malfunctioning appliance, or an internal component failure.

Error 06: Inverter output voltage is high
The AC output voltage is higher than the acceptable range, likely due to an internal regulation circuit failure.

Error 07: Overload time out
Your connected appliances are drawing more power than the inverter can supply. The inverter shuts down to protect itself. This often happens when high-power appliances like kettles, stoves, or heaters are used simultaneously.

Error 08: Inverter bus voltage is too high
The internal DC bus voltage has exceeded its safe limit, often caused by a sudden drop in load while solar input is high.

Error 09: Bus soft start failed
The inverter's power-up sequence has failed, which usually points to an internal component issue.

Error 11: Main relay failed
An internal hardware failure of the main relay. This requires professional repair.

Error 21 & 22: Voltage sensor error
The sensor measuring the AC output (21) or grid voltage (22) is faulty. This is an internal component failure.

Error 23, 24, 25: Current sensor error
A fault with the sensor measuring the output (23), grid (24), or load (25) current. This is an internal hardware issue.

Error 26: Inverter grid over current error
Excessive current has been drawn from the grid, possibly due to an external short circuit or internal failure.

Error 27: Inverter radiator over temperature
The heatsink has become too hot, usually caused by poor ventilation, a blocked fan, or sustained heavy loads in a hot environment.

Error 31: Solar charger battery voltage class error
A mismatch exists between the detected battery voltage and the inverter's settings. Ensure the correct voltage is configured.

Error 32 & 33: Solar charger current error
The MPPT's current sensor is faulty (32) or the charge controller cannot regulate the current (33). This is a critical internal fault.

Error 41 & 42: Grid voltage low or high
The incoming utility (ZESA) voltage is below the acceptable range (41) or too high (42), often due to a brownout or power surge.

Error 43 & 44: Grid frequency low or high
The grid frequency has dropped below (43) or exceeded (44) the inverter's safe operating range, indicating an issue with the utility supply.

Error 51, 52, 53, 55, 57: Internal system errors
These codes (Over current protection, Bus voltage too low, Soft start failed, DC voltage in AC output, Control sensor error) all point to serious internal hardware failures that require professional service.

Error 56: Battery connection is open
The inverter does not detect a proper connection to the battery bank, caused by a loose terminal, blown fuse, or disconnected cable.

Error 58: Inverter output voltage is too low
The inverter's AC output voltage is below the required level, possibly due to a very heavy load or an internal fault.

Warning 61 & 62: Fan is locked
The primary (61) or secondary (62) fan is blocked or has failed while the inverter is operating. This can quickly lead to an over-temperature fault.

Warning 63: Battery is over-charged
The battery voltage has exceeded the safe charging limit. The inverter will stop charging to protect the batteries.

Warning 64: Low battery
A pre-emptive warning that your battery is low on charge. It appears before the inverter shuts down with Error 04. Reduce your load to prolong runtime.

Warning 67: Overload
The power being drawn exceeds the inverter's capacity. The inverter will beep before shutting down with Error 07. Reduce the load immediately.

Warning 70: Output power derating
The inverter is reducing its power output to prevent overheating, typically due to heavy loads or poor ventilation.

Warning 72 & 73: Solar charger stops (Low Batt / High PV Volt)
Charging has paused because the battery voltage is too low (72) or the PV input voltage from the panels is too high (73).

Warning 76 & 77: Communication or Parameter error
The inverter has lost communication with the charge controller (76) or one of its settings has become corrupted (77). A factory reset may solve a parameter error.

How do I reset my Must inverter after a fault?
First, resolve the cause of the fault (e.g., unplug a high-power appliance if it's an overload). Then, perform a soft reset by turning off the Grid supply, then the PV isolator, then the inverter itself. Wait one minute. Turn everything back on in the reverse order (Inverter, PV, Grid).

What is the most common inverter fault in Zimbabwe?
Overload (Error 07) and Low Battery (Error 04) are extremely common, especially with unpredictable grid availability. Managing your load and allowing sufficient time for solar charging are key to avoiding these.

What is error 7 on a Must inverter?
Error 07 is an "Overload time out." The inverter has shut down after running above its rated capacity for too long. You must reduce the number of appliances being used at the same time.


Polaris Systems: Our approach works so well because we provide a single point of contact for every customer, creating multiple efficiencies. We aim to ensure a seamless experience, resulting in partnerships that deliver improved value and minimal downtime. This is how we achieve true customer satisfaction.

We are available 24/7, 365 days a year. Contact us anytime!