Inverters invert the DC electricity yielded by PV arrays into usable AC electricity. Inverters are also the ones where solar inverter failure causes isolation faults in solar systems, so it’s essential to understand how they work and how you can resolve an isolation fault if it occurs in your system. Solar panel costing will help you with solar inverter isolation faults, and help you diagnose solar PV inverter problems.

Solar PV Inverter problems – Isolation Fault

How Does An Isolation Fault Occur On A Solar Inverter? 

There are several solar inverter failure causes of isolation faults in solar PV systems. The common Solar PV inverter problem is when the DC input voltage flows beyond its limit than the maximum allowed by the inverter or due to DC leakage to the AC (PE). Moreover, there is poor or corrosive insulation between the live conductive terminal of the inverter and the ground. Other causes that lead to isolation faults include open circuit faults and short circuit faults. Other solar inverter failure causes include damaged or loose connections, incorrect wiring, and faulty components. Suppose you encounter isolation errors on your solar inverter LCD. In that case, it means that some parts of the Solar PV inverter are facing problems and are damaged by liquid or moisture and can no longer function. Improperly maintained Solar PV inverters may be one of the solar inverter failure causes of isolation faults. 

However, Solar Panel Costing helps you in providing all the information about the PV panel size, solar installation, and solar inverters’ inspection, repair, and maintenance. As per your property’s panel requirement, you can estimate the Solar Panel Cost Calculator cost per required kWh on the Solar Panel Costing page.

 Solar PV inverter problems – Isolation Fault

 Isolation fault happens due to

Solar inverters are challenging components; if any of these components go wrong, they may stop your inverter from rendering power or cause it to fail. 

The common malfunctioning of inverter isolation faults might happen due to:

  • Solar inverter isolation faults can occur when the solar inverter detects an open circuit or shorted circuit condition. 
  • The solar panels themselves are faulty.
  • The battery hasn’t been recharged fully. 
  • The wiring between the inverter and its solar panels is damaged.
  • Usually, Faulty batteries cause physical damage or excessive heat buildup inside them.
  • Solar inverter isolation faults occur when there is a problem with the wiring between your solar inverter and the grid. 
  • If the solar inverter is not getting enough power from your solar PV panels. 

In all cases, you might have trouble energizing your home, and severe circumstances may cause massive damage. 

If you presume your solar inverter has suffered an isolation fault, you may engage with the solar inverter maintenance specialist. However, Solar Panel Costing specialists and a certified team provide you with the best services in the UK. 

Isolation Fault troubleshooting 

Inverter fault is the most common and dangerous problem in solar power systems. It is an issue that can shut down your PV system, so it is essential to prevent and troubleshoot an isolation fault in a solar inverter.

  • Check the voltage on solar panel connections, ensuring no faults in those connections. An isolation fault may occur when the power from your solar panel stops flowing through your inverter, causing it to shut down.
  • Replace any faulty, poorly insulated, or damaged components like corrosive wires, faulty fuses or circuit breakers, etc. If one of your wires is loose or disconnected, that can be one solar inverter failure that causes an isolation fault due to voltage or current fluctuation.

Check for ground fault continuity testing.

  • Disconnect the DC switch of each PV array (DC combiner box) to diagnose the ground fault. With the multimeter, pinpoint the continuity between the positive PV string terminal and the ground terminal, and do the same with the negative one. 
  • The neutral and ground wire impedance should be zero or close to zero

Dirt accommodation.

  • Inverters have electrical, mechanical, and other components that need periodic maintenance. If dirt collects, this will lead to current and voltage fluctuation, or the PV inverter would provide no more operation due to contamination with filth or dampness. 

Isolation Fault due to moisture

You can troubleshoot it onsite. In most cases, due to moisture in the morning, isolation faults occur. To troubleshoot the problem, do the following steps.

  • Powered-off inverter AC isolator, DC isolator PV array connected with the inverter, and a main power supply switch. 
  • Wait a minute, power ON the PV array DC and AC isolator from the pull-up/down mechanical switch. Suppose there is still an error on the solar inverter for single-phase inverters or three-phase inverters. Then contact the solar inverter faults expert. You may partner with Solar Panel Costing as they provide the best Solar Inverter panel services in UK towns. Moreover, you can check the Solar Panel Cost Calculator calculates the solar panel cost per property size.

Check the DC Voltage 

  • Powered off and disconnect the string and optimizer
  • Powered off the inverter from the switch
  • Leave it ON if the PV Array DC isolator is deployed with an inverter or protection switch.
  • Then, powered the inverter and checked the DC voltage (HVDC) on display and if the error would display on the LCD. Then it is better to engage with the inverter faults diagnosis specialist. 

Locate isolation fault using insulator tester and branch cables to test string resistance

  1. The maximum string voltage and current should be approximately 50V and 500 milliamperes, respectively.
  2. Join the +/- connectors of the PV string’s first and last optimizers to the branch cable. 
  3. Set the insulation tester, and select 500V testing.
  4. Inspect the insulation resistance for the 1-phase solar inverter. It should be 600k ohms; for 3-phase, it would be less or equal to 1 mega-ohm. 
  5. Always use a branch cable to connect the tester’s negative and positive output connectors.

A short or open circuit causes solar inverter faults. If you suspect an isolation fault, turn off the power to the inverter and then disconnect all cables from the inverter. Then, use a test for voltage (multimeter) at different points on your inverter. There may be an isolation fault if none of these points are voltage-positive. 

Solar inverter faults troubleshooting 

Ways to avoid a faulty connection from henceforth again

An isolation fault can occur when there is a loose connection between the solar inverter and the PV array. This can happen if the inverter is not adequately grounded or the wiring is not done correctly. To take safety measures against isolation fault in the future, you need to follow this measuring:

  • Assuring that the PV inverter has connections to the grounded wire.
  • Ensuring that cables are not damped or corrosive.
  • Ensure the DC disconnect switch (DC combiner box) is installed correctly and appropriately.
  • Use proper cable sizing of SWG/AWG to minimize voltage drop.
  • Install surge protection devices at the DC coupling system’s inverter and PV array sides.

Conclusion

The diagnosis and troubleshooting of Solar inverter isolation faults are straightforward. Setting adjustments to reboot your PV system is needed. If you encounter isolation fault errors on your solar inverter, you must fix the problem immediately by contacting an expert to resolve the issue.

 Contact Solar Panel Costing online by filling out the quote form on their web page, or call them at +443301335760 for help with your isolation fault today.

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