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Fronius Primo Solar Inverter Faults and Repairs

Austrian solar inverter manufacturer Fronius began manufacturing solar inverters in 1994 and are widely regarded as one of the best manufacturers of quality solar PV inverters in the world.

We have a lot of experience in working with Fronius equipment, so if you would like help with diagnosing faults, carrying out servicing or repairs and are currently without an installer then we will be happy to help.

Fronius Primo solar inverters have LCD displays on the front of the chassis that providing it's working, will highlight any errors with the solar inverter or the solar PV system that it runs, we have listed and described common faults with Fronius Primo solar inverters and what action to take to resolve them below:

Fronius IG, IG Plus and IG TL Inverter Faults and Repairs

All Solar Inverter Fault Codes, Warnings and Troubleshooting

Solar PV System Repairs

Solar Inverter Replacement

Repair Fronius Primo Inverter

Fronius Primo

Fronius Primo Solar Inverter LED Indicators:

  • Green Light - The green LED indicates that the solar inverter is operating correctly.

  • Orange Light - The orange LED indicates that the solar inverter is going through its startup sequence or in standby.

  • Red Light - The red LED indicates that the solar inverter has detected a fault condition. A fault description will appear on the display.

Fronius Primo Solar Inverter Faults and Warnings:

Some of the advice we give related to identifying, confirming and or resolving some of the faults detailed below, starts with safely shutting down and restarting the solar inverter and the solar PV system. This is something that nearly all solar PV systems installed in the UK would have been designed to be carried out safely by the solar PV system owner. However, paperwork, schematics and manuals are not always clear or available, so if you have any concerns about how to do this, Contact us and we will be pleased to talk you through the process over the telephone at no charge.

How to Restart Fronius Primo Solar Inverters:

Leave everything near the supply meters turned on. At the solar inverter there will be an AC isolator, this is used to isolate the mains/grid supply from the solar inverter and to prevent the solar inverter from feeding solar power into the electrical system. Switch the AC isolator 'off', if the solar inverter is running correctly you will hear a clunk inside the machine and after a while a 'no-grid', 'missing grid' warning or similar on the LCD display.

Restart Fronius Primo Solar Inverter

AC Isolator

Near to and or built into the solar inverter will be a method of isolating the solar (DC) supply from the solar inverter. Often these are black and grey and will be labelled 'DC isolator' or similar. There might be two or more of these if the system is fed by multiple strings. If there isn't a seperate DC isolation device, there will be a way to isolate the DC supply built-in to the solar inverter itself (often a rotary style switch underneath), turn this 'off'.

When all of the lights on the solar inverter have gone out, reintroduce the AC/mains power supply by turning the AC isolator 'on'. Introduce the DC supply by turning all DC isolators 'on'.

This will restart the solar inverter, on the display it might show you progress during it's startup procedure. During startup is when the solar inverter carries out all of the tests needed before being able to connect the solar supply to the electrical system. If errors are found during testing they will be displayed on the screen or an indication light might come on. Make a note of any warning messages, warning lights and fault codes.

If the restart is succesful a green light will come on, sometimes flashing at first but once connected to the mains/AC supply remaining permenantly on. The LCD display will show how much power the solar PV system is generating. The solar PV system can be verified as working at the solar generation / Feed in Tariff (FIT) meter which will count on the display, the red light will pulse as it counts.

Fronius Primo Solar Inverter: No lights, No Display

Fronius Primo solar inverters are powered by the solar panels (the DC supply) and will startup at sunrise each day and shutdown at night. If you find the solar inverter with no lights or display working during the day, there is either a problem with the solar panels or with the solar inverter. Follow the shutdown and restart procedure outlined above and if the problem persists Contact us to discuss the next steps.

If you have the correct tools and are comfortable in doing so, isolate the AC and DC power supplies from the solar inverter and confirm that the incoming DC voltages are as expected by measuring between the positive and negative incoming terminals in DC isolators (if avalable) and or at the DC solar inverter inputs. Light conditions and the type of solar panel will affect voltages but as a rule of thumb anywhere from 30V-60V per panel x the number of panels connected in series in the string would be a reasonable voltage estimate.

No or very low DC voltage would suggest a problem with the solar panels, measuring the expected voltage at the isolator terminals and or the DC inputs, although additional testing should be carried out, would suggest a problem with the solar inverter. Contact us to discuss the next steps.

Fronius Primo Solar Inverter Fault Codes and Explanations:

* State 101 - Grid Voltage beyond specified limits - The solar inverter is measuring a grid voltage that is either too low or too high in relation to the parameters that the solar inverter has been set to safely operate within. A status 1xx fault such as this, will often be temporary, the solar inverter will monitor the grid and reconnect when the voltage is within range. If this fault persists and mains power is available to other local circuits then check that all isolators, MCBs and RCDs on the AC side of the solar PV system are 'On'.

Check fuses, isolators, Miniture Circuit Breakers (MCBs) and Residual Current Devices (RCDs) in and around consumer units, around the solar generation and mains/grid supply meters and see if anything marked 'solar PV' or you can see is related to the solar PV system is switched 'off'. The solar generation meter draws it's power from the mains so if this isn't on, this would be a strong indication that something heading toward the incoming grid/mains power supply has tripped off.

RCD

RCD

 

MCB

MCB

An RCD has a test button and is twice the width or a circuit breaker. An RCD that's switched itself 'off' is an indication that it has picked up an earth fault somewhere on the circuit that it protects, this fault could be anywhere on the circuit and might have been temporary.

- If an RCD has switched itself 'off' it's ok to try to turn it back 'on' again. If you meet with instant and strong resistance to closing the switch, leave it 'off'. If it stays on for a short while and switches off when the solar PV system has warmed up and begun to feed in power, there's most likely a problem with the solar PV system somewhere, leave the RCD turned 'off' and contact us to discuss the next steps.

If the RCD remains on for a few hours, weeks or days and then switches itself off, faults like these are often weather related. Damp cables and wet or windy conditions will often expose faults both physical and in design, with AC and DC cabling, connectors, solar panels and RCDs. Contact us to discuss the next steps.

If the RCD stays on, the solar inverter starts up and everything works fine in all conditions - all good.

- If a circuit breaker has switched 'off' this is an indication of either a short circuit, most likely a serious failure either within the solar inverter or with the solar inverter supply cable. Or for some other reason the circuit breaker has picked up a fault and isolated the circuit to prevent the solar inverter supply cable from becoming overloaded.

Turn on circuit breakers at your own risk, there is the potential to cause damage and only do so when you are able to access and inspect the solar inverter and all isolation equipment whilst it's in operation. If you meet instant and strong resistance, leave the circuit breaker 'off' and turn everything to do with the solar PV system 'off' remembering to also safely isolate the DC circuits.

If the circuit breakers stays on and then switches itself off after a few minutes, this is reasonably strong indication that the solar inverter has a serious internal fault. Turn off everything to do with the solar PV system including the DC isolators and contact us to discuss the next steps.

If the circuit breaker stays on, the solar PV inverter starts up and feeds power into the electrical system through the circuit breaker; although the circuit breaker will continue to protect the circuit, ideally a physical inspection and electrical test of the supply circuit including all isolators, circuit breakers, RCDs and electrical connections would also be carried out.

- Everything's 'on' but the error remains and the solar inverter won't start. If everything on the grid/mains power supply side including the solar generation meter is switched 'on', this would be an indication that there is either an internal fault within the solar inverter or there's a problem with the grid/mains power supply. Contact us to discuss the next steps.

* State 102 - AC Voltage Too High - The solar inverter is measuring a grid (mains) voltage that is too high in relation to the parameters that the solar inverter has been set to safely operate within. A status 1xx fault such as this, will often be temporary, the solar inverter will monitor the grid and reconnect when the voltage is within range. If this fault persists contact us to arrange for a solar engineer to visit to establish whether the fault lies with the solar inverter or with the grid.

* State 103 - AC Voltage Too Low - The solar inverter is measuring a grid (mains) voltage that is too low in relation to the parameters that the solar inverter has been set to safely operate within. A status 1xx fault such as this, will often be temporary, the solar inverter will monitor the grid and reconnect when the voltage is within range. If this fault persists and mains power is available to other local circuits then check that all isolators, MCBs and RCDs on the AC side of the solar PV system are 'On' and carry out the procedures outlined for * State 101 - Grid Voltage beyond specified limits above. If everything on the grid/mains power supply side including the solar generation meter is switched 'on', this would be an indication that there is either an internal fault within the solar inverter or there's a problem with the grid/mains power supply. Contact us to arrange for a solar engineer to visit to establish whether the fault lies with the solar inverter or with the grid/mains power supply.

* State 104 - Grid frequency Beyond Permitted limits - The solar inverter is measuring a grid frequency that is either too low or too high in relation to the parameters that the solar inverter has been set to safely operate within. A status 1xx fault such as this, will often be temporary, the solar inverter will monitor the grid and reconnect when the voltage is within range. If this fault persists and mains power is available to other local circuits then check that all isolators, MCBs and RCDs on the AC side of the solar PV system are 'On' and carry out the procedures outlined for * State 101 - Grid Voltage beyond specified limits above. If everything on the grid/mains power supply side including the solar generation meter is switched 'on', this would be an indication that there is either an internal fault within the solar inverter or there's a problem with the grid/mains power supply. Contact us to arrange for a solar engineer to visit to establish whether the fault lies with the solar inverter or with the grid/mains power supply.

* State 105 - AC Frequency Too High - The solar inverter is measuring a grid (mains) frequency that is too high in relation to the parameters that the solar inverter has been set to safely operate within. A status 1xx fault such as this, will often be temporary, the solar inverter will monitor the grid and reconnect when the frequency is within range. If this fault persists contact us to arrange for a solar engineer to visit to establish whether the fault lies with the solar inverter or with the grid.

* State 106 - AC Frequency Too Low - The solar inverter is measuring a grid (mains) frequency that is too low in relation to the parameters that the solar inverter has been set to safely operate within. A status 1xx fault such as this, will often be temporary, the solar inverter will monitor the grid and reconnect when the frequency is within range. If this fault persists and mains power is available to other local circuits then check that all isolators, MCBs and RCDs on the AC side of the solar PV system are 'On' and carry out the procedures outlined for * State 101 - Grid Voltage beyond specified limits above. If everything on the grid/mains power supply side including the solar generation meter is switched 'on', this would be an indication that there is either an internal fault within the solar inverter or there's a problem with the grid/mains power supply. Contact us to arrange for a solar engineer to visit to establish whether the fault lies with the solar inverter or with the grid/mains power supply.

* State 107 - No AC Grid Detected - The solar inverter is not measuring a grid (mains) voltage suggesting that mains power to the unit has been disconnected. A status 1xx fault such as this, will often be temporary, the solar inverter will monitor the grid and reconnect when mains voltage returns such as might happen when mains power returns after a power cut. If this fault persists and mains power is available to other local circuits then check that all isolators, MCBs and RCDs on the AC side of the solar PV system are 'On' and carry out the procedures outlined for * State 101 - Grid Voltage beyond specified limits above. If everything on the grid/mains power supply side including the solar generation meter is switched 'on', this would be an indication that there is either an internal fault within the solar inverter or there's a problem with the grid/mains power supply. Contact us to arrange for a solar engineer to visit to establish whether the fault lies with the solar inverter or with the grid/mains power supply.

* State 108 - Islanding Detected - The solar inverter understands that there has been a mains failure (a power cut). A status 1xx fault such as this, will often be temporary, the solar inverter will monitor the grid and reconnect when mains voltage returns. If this fault persists and mains power is available to other local circuits then check that all isolators, MCBs and RCDs on the AC side of the solar PV system are 'On' and carry out the procedures outlined for * State 101 - Grid Voltage beyond specified limits above. If everything on the grid/mains power supply side including the solar generation meter is switched 'on', this would be an indication that there is either an internal fault within the solar inverter or there's a problem with the grid/mains power supply. Contact us to arrange for a solar engineer to visit to establish whether the fault lies with the solar inverter or with the grid/mains power supply.

* State 109 - General Mains Error - The solar inverter has detected a fault with the AC power supply, this could be due to damaged or faulty AC wiring or it might be picking up a disturbance on the grid/mains power supply power network. If this fault persists and mains power is available to other local circuits then check that all isolators, MCBs and RCDs on the AC side of the solar PV system are 'On' and carry out the procedures outlined for * State 101 - Grid Voltage beyond specified limits above. If everything on the grid/mains power supply side including the solar generation meter is switched 'on', this would be an indication that there is either an internal fault within the solar inverter or there's a problem with the grid/mains power supply. Contact us to arrange for a solar engineer to visit to establish whether the fault lies with the solar inverter or with the grid/mains power supply.

* State 112 - The RCMU has detected a fault current in the Inverter - The solar inverter is measuring too much voltage from the panels. Assuming that this is an existing installation that has been specified correctly, hasn't recently been changed or added to and has operated before without problems. This could mean either a problem with the panels or with the solar inverter. We would advise that you book a solar repair engineer to test the DC side of the system including the solar inverter.

* State 301 - Overcurrent AC - The solar inverter is measuring an AC current peak on the grid/mains power supply. The solar inverter will monitor the grid and reconnect when the current is within range. If this fault persists then contact us to arrange for a solar engineer to visit to establish whether the fault lies with the solar inverter or with the grid.

* State 302 - Overcurrent DC - The solar inverter is measuring too much current from the panels. Assuming that this is an existing installation that has been specified correctly, hasn't recently been changed or added to and has operated before without problems. This could mean either a problem with the panels or with the solar inverter. We would advise that you book a solar eEngineer to test the DC side of the system including the solar inverter.

* State 303 - Over Temperature - The ambient temperature around the solar inverter is too hot. This could be due to a number of factors, for example 1) If the solar inverter is exposed to direct sunlight 2) If the solar inverter has been installed without adequate ventilation around the chassis which would allow excess heat to dissipate 3) The solar inverter's components are getting too hot due to an internal component fault. If the unit isn't running hot and if after the system has been safely shutdown and restarted this condition persists then contact us.

* State 304 - Over Temperature Cooling Element - The temperature inside the solar inverter is too hot. This could be due to a number of factors, for example 1) If the solar inverter is exposed to direct sunlight 2) If the solar inverter has been installed without adequate ventilation around the chassis which would allow excess heat to dissipate 3) The solar inverter's components are getting too hot due to an internal component fault 4) Dust, fluff or a similar obbstruction is blocking the vents or fans inside the chassis. If after the system has been safely shutdown and restarted this condition persists then contact us.

* State 305 - Feed in Process Not Possible - If after the system has been safely shutdown and restarted this condition persists then contact us.

* State 306 - Power Low - Intermediate circuit voltage has dropped below permissible threshold value for feed in. This could mean either a problem with the panels or with the solar inverter. If after the system has been safely shutdown and restarted this condition persists then contact us.

* State 307 - DC Low - The solar inverter is measuring low DC voltage that it believes is due to low solar irradiance. Low irradiance (sunlight) is to be expected in the mornings and evenings, if solar panels are in shade and on very cloudy days, if the fault passes on it's own relatively quickly the solar inverter might simply be responding to external conditions like this.

However should there be plenty of sunlight and assuming that this is an existing installation that has been specified correctly, no changes near the installation area have been made that might have caused damage or induced shading, and the system has operated before without problems. This could indicate either a problem with the solar panels or with the solar inverter. If you are concerned and or the fault doesn't clear itself, then we would advise that you book a solar repair engineer to test the DC side of the system including and excluding the solar inverter.

If you have the correct tools and are comfortable in doing so, isolate the AC and DC power supplies from the solar inverter and confirm that the incoming DC voltages are as expected by measuring between the positive and negative incoming terminals in DC isolators (if avalable) and or at the DC solar inverter inputs. Light conditions and the type of solar panel will affect voltages but as a rule of thumb anywhere from 30V-60V per panel x the number of panels connected in series in the string would be a reasonable voltage estimate.

No or very low DC voltage would suggest a problem with the solar panels, measuring the expected voltage at the isolator terminals and or the DC inputs, although additional testing should be carried out, would suggest a problem with the solar inverter. Contact us to discuss the next steps.

* State 308 - Intermediate circuit voltage too high - The solar inverter has detected a discrepency with the voltage from the AC power supply, this could be due to damaged or faulty AC wiring or it might be picking up a disturbance on the grid/mains power supply power network. If this fault persists then contact us to arrange for a solar engineer to visit to establish whether the fault lies with the solar inverter or with the grid.

* State 309 - DC input voltage MPPT 1 too high - The solar inverter is measuring DC voltage that is above range. Assuming that this is an existing installation that has been specified correctly, there is sufficient irradiation (sunlight), no changes near the installation area have been carried out and the system has operated before without problems, then we would advise that you book a solar repair engineer to test the DC side of the system including the solar inverter.

* State 313 - DC input voltage MPPT 2 too high - The solar inverter is measuring DC voltage that is above range. Assuming that this is an existing installation that has been specified correctly, there is sufficient irradiation (sunlight), no changes near the installation area have been carried out and the system has operated before without problems, then we would advise that you book a solar repair engineer to test the DC side of the system including the solar inverter.

* State 401 - No internal communication with power stage set - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 406 - Temperature sensor on the PINCI board faulty - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 407 - Temperature sensor on the heat sink faulty - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 408 - Direct current feed in - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 412 - Value for fixed voltage is set higher than the open circuit voltage of the PV-generator - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 415 - No END-enabling signal - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 416 - Communication with IG Brain not possible - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 417 - Hardware ID Collision - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 419 - Two or more power stacks with identical Unique ID - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 421 - Hardware ID sequence error - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 425 - Communication with the power stage set is not possible - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 426 - Possible hardware fault - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 427 - Possible hardware fault - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 428 - Possible hardware fault - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 431 - Software probleme - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 436 - Error transmission faulty - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 437 - Power stage set problem - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 438 - Error during * State code transmission - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 443 - Intermediate circuit voltage too low or asymmetric - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 445 - Impermissible limit value settings - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 447 - Insulation fault - This error is generated when during normal operation of the solar inverter, a leakage current to ground/earth is detected on the DC side of the system. Although it is also possible that the solar inverter generates this alarm message due to AC leakage currents connected to the capacitive nature of the solar panels compared to ground/earth or there could be a problem with the solar inverter itself.

solar PV Cable

For as long as the situation persits then the solar inverter will not startup. Earth / Ground Faults (also called Insulation or Isolation Faults) often present themselves when it is raining or at times of high humidity when moisture can enter the solar PV system through damaged solar panels, connectors or cabling. These faults often clear when weather conditions improve but they will not get better by themselves, most often degrading and becoming more dangerous over time.

We would advise that you book a solar repair engineer's visit in order to carry out a full solar system test, identify the source and rectify the fault. We've written more about how to identify and repair ground faults here: Ground Faults, Isolation (ISO) Faults, RISO Low Faults and Insulation Resistance Faults with Solar PV Systems

* State 448 - Neutral conductor not connected - The solar inverter has lost it's neutral connection to the grid (mains). Assuming that this is an existing installation that has been specified correctly, hasn't recently been changed or added to and has operated before without problems. This could mean either a problem with the mains, the solar inverter's supply circuit or with the solar inverter. We would advise that the AC side of the system is disconnected using either an isolator located near the solar inverter (if available) or at the solar inverter's circuit breaker and contact us to test the AC side of the system including and excluding the solar inverter.

* State 450 - Guard not found - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 451 - Memory error detected - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 452 - Communication error between the processors - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 453 - Short-term grid voltage error - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 454 - Short-term grid frequency error - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 456 - Anti-islanding function is no longer being implemented correctly - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 457 - Grid relay sticking - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 459 - Error when recording the measuring signal for the insulation test - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 460 - Reference voltage source for the digital signal processor (DSP) is working out of tolerance - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 461 - DSP data memory error - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 462 - Error during DC feed monitoring routine - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 463 - Reversed AC polarity, AC connector inserted incorrectly - Assuming that this is an existing installation that has been specified correctly, hasn't recently been changed or added to and has operated before without problems. This could mean either a problem with the mains, the solar inverter's supply circuit or with the solar inverter. We would advise that the AC side of the system is disconnected using either an isolator located near the solar inverter (if available) or at the solar inverter's circuit breaker and contact us to test the AC side of the system including and excluding the solar inverter.

* State 474 - RCMU sensor faulty - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 475 - DC insulation fault - This error is generated when during normal operation of the solar inverter, a leakage current to ground/earth is detected on the DC side of the system. Although it is also possible that the solar inverter generates this alarm message due to AC leakage currents connected to the capacitive nature of the solar panels compared to ground/earth or there could be a problem with the solar inverter itself.

Wet solar oanels

For as long as the situation persits then the solar inverter will not startup. Earth / Ground Faults (also called Insulation or Isolation Faults) often present themselves when it is raining or at times of high humidity when moisture can enter the solar PV system through damaged solar panels, connectors or cabling. These faults often clear when weather conditions improve but they will not get better by themselves, most often degrading and becoming more dangerous over time.

We would advise that you book a solar repair engineer's visit in order to carry out a full solar system test, identify the source and rectify the fault. We've written more about how to identify and repair ground faults here: Ground Faults, Isolation (ISO) Faults, RISO Low Faults and Insulation Resistance Faults with Solar PV Systems

* State 476 - Driver supply voltage too low - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 479 - Intermediate circuit voltage relay is switched off - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 480 - Functional incompatibility (one or more PC boards in the solar inverter are not compatible with each other, e.g. after a PC board has been replaced) - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 481 - Functional incompatibility (one or more PC boards in the solar inverter are not compatible with each other, e.g. after a PC board has been replaced) - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 482 - Start-up incomplete - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 483 - Voltage UDC fixed on MPP2 string out of limits - The solar inverter is measuring too much voltage from the panels on MPPT 2. Assuming that this is an existing installation that has been specified correctly, hasn't recently been changed or added to and has operated before without problems. This could mean either a problem with the panels or with the solar inverter. We would advise that the DC side of the system is disconnected using either the built in DC isolator at the bottom of the solar inverter or the DC Isolator installed between the panels and the solar inverter (if available) and contact us to test the DC side of the system including and excluding the solar inverter.

* State 485 - CAN transmit buffer is full - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 489 - Permanent overvoltage on intermediate circuit capacitor (five 479 status codes in a row) - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 501 - 100k Ohm module grounding measurement detects failure - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 502 - An isolation fault between DC+ or DC- to earth has been detected - This error is generated when during normal operation of the solar inverter, a leakage current to ground/earth is detected on the DC side of the system. Although it is also possible that the solar inverter generates this alarm message due to AC leakage currents connected to the capacitive nature of the solar panels compared to ground/earth or there could be a problem with the solar inverter itself.

solar PV system testing

For as long as the situation persits then the solar inverter will not startup. Earth / Ground Faults (also called Insulation or Isolation Faults) often present themselves when it is raining or at times of high humidity when moisture can enter the solar PV system through damaged solar panels, connectors or cabling. These faults often clear when weather conditions improve but they will not get better by themselves, most often degrading and becoming more dangerous over time.

We would advise that you book a solar repair engineer's visit in order to carry out a full solar system test, identify the source and rectify the fault. We've written more about how to identify and repair ground faults here: Ground Faults, Isolation (ISO) Faults, RISO Low Faults and Insulation Resistance Faults with Solar PV Systems

* State 509 - No energy has been fed into the grid in the past 24 hours - This error is stating that the solar inverter has not fed in power within the last 24 hours. This could be for a number of reasons including that the panels have been covered in snow, are excessively dirty, the solar inverter has developed a faiult or the panels have not been able to generate power for some other reason. If after the system has been inspected for external influences and safely shutdown and restarted this condition persists then contact us.

* State 515 - Unable to communicate with filter - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 516 - No communication possible with the storage unit - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 517 - Power derating caused by too high a temperature - The ambient temperature around the solar inverter is too hot. This could be due to a number of factors, for example 1) If the solar inverter is exposed to direct sunlight 2) If the solar inverter has been installed without adequate ventilation around the chassis which would allow excess heat to dissipate 3) The solar inverter's components are getting too hot due to an internal component fault. If the unit isn't running hot and if after the system has been safely shutdown and restarted this condition persists then contact us.

* State 522 - DC low String 1 - The solar inverter is measuring low DC voltage on string 1. Assuming that this is an existing installation that has been specified correctly, there is sufficient irradiation (sunlight), no changes near the installation area have been carried out and the system has operated before without problems, then we would advise that you book a solar repair engineer to test the DC side of the system including the solar inverter.

If you have the correct tools and are comfortable in doing so, isolate the AC and DC power supplies from the solar inverter and confirm that the incoming DC voltages are as expected by measuring between the positive and negative incoming terminals in DC isolators (if avalable) and or at the DC solar inverter inputs. Light conditions and the type of solar panel will affect voltages but as a rule of thumb anywhere from 30V-60V per panel x the number of panels connected in series in the string would be a reasonable voltage estimate.

No or very low DC voltage would suggest a problem with the solar panels, measuring the expected voltage at the isolator terminals and or the DC inputs, although additional testing should be carried out, would suggest a problem with the solar inverter. Contact us to discuss the next steps.

* State 523 - DC low String 2 - The solar inverter is measuring low DC voltage on string 2. Assuming that this is an existing installation that has been specified correctly, there is sufficient irradiation (sunlight), no changes near the installation area have been carried out and the system has operated before without problems, then we would advise that you book a solar repair engineer to test the DC side of the system including the solar inverter.

If you have the correct tools and are comfortable in doing so, isolate the AC and DC power supplies from the solar inverter and confirm that the incoming DC voltages are as expected by measuring between the positive and negative incoming terminals in DC isolators (if avalable) and or at the DC solar inverter inputs. Light conditions and the type of solar panel will affect voltages but as a rule of thumb anywhere from 30V-60V per panel x the number of panels connected in series in the string would be a reasonable voltage estimate.

No or very low DC voltage would suggest a problem with the solar panels, measuring the expected voltage at the isolator terminals and or the DC inputs, although additional testing should be carried out, would suggest a problem with the solar inverter. Contact us to discuss the next steps.

* State 558 - Functional incompatibility (one or more PC boards in the solar inverter are not compatible with each other, e.g. after a PC board has been replaced) - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 560 - Power reduction due to over-frequency - The solar inverter has reduced output power due to excessive grid fre-quency. If this fault persists then contact us to arrange for a solar engineer to visit to establish whether the fault lies with the solar inverter or with the grid.

* State 566 - Arc detector switched off (e.g. during external arc monitoring) - The status code is displayed every day until the arc detector is reactivated. Confirm status code by pressing 'Enter'.

* State 705 - Conflict when setting the inverter number (e.g. number already assigned) - This is a State code that would only be expected to be seen on initial configuration. If after the system has been safely shutdown and restarted this condition persists then contact us.

* State 710 - Solar Net - Keep alive signal missing - This is a State code that would only be expected to be seen on initial configuration. If after the system has been safely shutdown and restarted this condition persists then contact us.

* State 721 - EEPROM has been reinitialised or EEPROM is faulty - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 731 - Initialisation error - USB flash drive is not supported - This is a State code that would only be expected to be seen on initial configuration. If after the system has been safely shutdown and restarted this condition persists then contact us.

* State 732 - Overcurrent on USB stick - This is a State code that would only be expected to be seen on initial configuration. If after the system has been safely shutdown and restarted this condition persists then contact us.

* State 733 - No USB flash drive connected - This is a State code that would only be expected to be seen on initial configuration. If after the system has been safely shutdown and restarted this condition persists then contact us.

* State 734 - Update file not recognised or not present - This is a State code that would only be expected to be seen on initial configuration. If after the system has been safely shutdown and restarted this condition persists then contact us.

* State 735 - Update file does not match the device, update file too old - This is a State code that would only be expected to be seen on initial configuration. If after the system has been safely shutdown and restarted this condition persists then contact us.

* State 736 - Write or read error occurred - This is a State code that would only be expected to be seen on initial configuration. If after the system has been safely shutdown and restarted this condition persists then contact us.

* State 738 - Log file cannot be saved (e.g. USB flash drive is write-protected or full) - This is a State code that would only be expected to be seen on initial configuration. If after the system has been safely shutdown and restarted this condition persists then contact us.

* State 743 - Error occurred during update process - This is a State code that would only be expected to be seen on initial configuration. If after the system has been safely shutdown and restarted this condition persists then contact us.

* State 745 - Update file corrupt - This is a State code that would only be expected to be seen on initial configuration. If after the system has been safely shutdown and restarted this condition persists then contact us.

* State 751 - Time lost - Reset the time and date, if this doesn't clear this code or if after a safe shutdown and restart this State code persists contact us.

* State 752 - Real Time Clock module communication error - Reset the time and date, if this doesn't clear this code or if after a safe shutdown and restart this State code persists contact us.

* State 757 - Hardware error in the Real Time Clock module - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 758 - Internal error: Real Time Clock module is in emergency mode - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

* State 766 - Emergency power limitation has been activated (max. 750 W) - If after the system has been safely shutdown and restarted this condition persists the inverter has a fatal error and should be replaced. There are a few ways that we can help with this: Solar Inverter Replacement

Solar PV System Repairs

Solar Inverter Replacement

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Solar Inverter Recycling: - Recycling Fronius Inverters

Fronius inverters contain valuable materials such as copper and aluminium, these materials are in high demand and recycling them is significantly less energy intensive than extracting them from ore.

If you find yourself with a damaged or faulty Fronius inverter, we will be pleased to help you recycle it.

Solar PV System Repairs

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Solar Power System Testing, Servicing & Maintenance

Regular solar PV system testing, servicing and maintenance will extend the life of your solar PV system and ensure that solar panels are always operating safely and at their best, whilst maximising yields.

We offer complete safety and performance testing for solar PV power systems of any size. Includes solar panels, cables, solar inverters, isolators and mains connections.

We provide solar power system testing and maintenance services for residential, commercial, industrial and agricultural clients across Southern, South West England and the West Midlands, with specialist experience working with farmers, developers and commercial and industrial buildings owners.

Solar Power System Testing, Servicing & Maintenance

 

Solar PV Inverter Replacement

If you have a faulty solar inverter, we offer an efficient, value for money, hassle free solar inverter replacement service. We offer good advice and install quality equipment with comprehensive warranty and support options. We will test the rest of the system as part of the service, take care of all hardware deliveries, record your new unit's serial number and confirm the warranty details with the manufacturer.

Our solar electricians work cleanly and will dispose of any unwanted boxes, faulty equipment and packaging.

Many modern solar inverters can now use wireless home networks to transmit solar generation data to PCs, tablets and smartphones, so if you would like something like this, let us know and we will be happy to set it up as part of the installation.

Solar PV Inverter Replacement

 

Mains/Grid Isolation and Surge Protection

Mains/AC Surge Protection Solar PV Systems

A whole house surge protector is installed to provide protection from transient overvoltages originating from the mains/grid. A whole house surge protector is installed directly inline and as close as possible to the incoming mains/grid supply meter, this allows for surge protection for all circuits and equipment including solar inverters, routers, stereos and other sensitive electrical equipment within the network. The addition of a 100Amp lockable isolator also allows for safe and convenient isolation of all electrical equipment within the network including consumer units, solar inverters, battery storage units and EV chargers from the mains/grid in one place.

Surge protectors are in compliance with the recently updated 18th edition amendment 2 of BS7671.

Mains/Grid Isolation and Surge Protection

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Articles: Further Information, Calculators & Solar Inverter Fault Codes

Lots of articles, calculators and technical information including links for further reading. Covering a range of topics related to the installation and maintenance of solar photovoltaic and electrical systems in the UK.

/Solar PV Information Articles

Fronius IG / IG Plus Inverter Faults and Repairs

Fronius IG and IG Plus solar inverters have LCD displays on the front of the chassis that providing it's working, will highlight any errors with the solar inverter or the solar PV system that it runs.

How to provide power to a house using a portable generator

We look at changeover switches, the importance of earthing, generator loadings, isolating non essential loads. Where to locate the generator and how best to safely isolate the grid/mains power supply and switch to a generator supply.

Ground Faults, Isolation (ISO) Faults, RISO Low Faults and Insulation Resistance Faults with Solar PV Systems

After a number of years exposed to wind, rain, snow, ice and sometimes animals; solar panel systems can start to develop faults. The most common faults we find related to exposure are ground faults, isolation (ISO) faults, RISO low faults and insulation resistance faults. In this article we take a look at what these faults are, the possible causes and what steps are taken to identify and resolve them.

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What Our Customers Say:

"In Balance contacted us promptly after we made an enquiry, Glen telephoned and arranged to visit our property to identify the fault, he arrived the following day! Brilliant as when the system is down it isn't earning us money. We decided to have a new inverter installed as our original one was 9 years old. Glen ordered the unit which was delivered to our property he then arrange to fit the unit the following day. He really could not have done it any quicker so thank you for that. Good job done for reasonable money. Highly recommended." - Geoff Thomas, Abingdon

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Case Studies

We've carried out Solar PV System design, installation, testing, repair and maintenance work on solar PV systems of all shapes and sizes all across the UK.

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Areas Served:

We are located in Wanborough, very close to Swindon in Wiltshire, Southern England, UK. From here we service clients within a 90 minute driving radius including the towns, cities and regions below:

Swindon: Abingdon, Aldbourne, Amesbury, Andover, Banbury, Basingstoke, Bath, Berkshire, Bicester, Blunsdon, Box, Bracknell, Bradford on Avon, Bridgwater, Bristol, Buckingham, Burford, Burnham on Sea, Calne, Camberley, Cardiff, Carterton, Cheltenham, Chippenham, Chipping Norton, Chipping Sodbury, Cirencester, Corsham, Cricklade, Devizes, Didcot, Evesham, Eynsham, Faringdon, Frome, Fleet, Glastonbury, Gloucester, Gloucestershire, Hampshire, Henley-on-Thames, Highclere, Highworth, Hook, Hungerford, Keynsham, Kingsclere, Lambourn, Lechlade, Ledbury, Ludgershall, Lyneham, Maidenhead, Malmesbury, Marlborough, Marshfield, Melksham, Minety, Newbury, Newport, Oxford, Oxfordshire, Pewsey, Purton, Ramsbury, Reading, Ross on Wye, Royal Wootton Bassett, Salisbury, Shaftesbury, Shalbourne, Slough, Southampton, Stow, Stratford upon Avon, Stroud, Swindon, Tewkesbury, Thatcham, Tidworth, Trowbridge, Wanborough, Wantage, Warminster, Weston Super Mare, Wiltshire, Winchester, Windsor, Witney, Wokingham, Worcester, Wroughton and Yate.

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