Troubleshooting an Inverter

Written By: Roger Published In: String Inverters Overview Created Date: 2015-01-21 Hits: 9689

Issues with inverters are often due to external influences, GRID VOLTAGE being one of these. Often a main line which either has several PV installations on it or is near a main transformer with see voltages around the 250 – 253 volts AC. These are on the operating upper levels and surges above this voltage will either trigger a fault code or an inverter to switch off (This will depend on the model and manufacturer but check the inverter specifications).

In the event that this is a common issue, then it may be possible to adjust the tripping point on the inverter but this should be done in consultation with the manufacturer who will advise on the best parameters.

Inverter has stopped working?

 

With all inverters the fact that it has stopped working does not necessarily mean that the inverter is at fault.

 

Most inverters do have error reporting codes and as such this is the first place to look for a clue to the problem.

 

Common issues are RCCD or MCB’s tripping and it worth exploring the possibility of there being either a fault on the 240 volt supply wire from the inverter to the grid connection. This could be damage to the wire or even ingress of water or corrosion.

 

It is important to understand that most major manufacturers of inverters operate their own warranty / service departments and while NuVision Energy is willing to help facilitate the repair /replacement of the inverter it is not within their contract to provide replacements unless expressly requested and agreed with the manufacturers.

 

In the event that the inverter is at fault the following information must be provided in order to process the service request:

 

Inverter manufacturer and Model

Inverter serial Number

Inverter fault code or issue in the event of display failure

Invoice date and installation date 

 

With this information NuVision Energy will contact the manufacturer and be advised by them of the remedy of either an engineer site visit or a replacement.

 

In the event of a replacement most manufacturers operate a standard fee for the installer to visit site and replace the inverter. The installer will be advised of this amount before the replacement inverter is dispatched.    

 

Other Common problems.

 

Issues with inverters are often due to external influences, GRID VOLTAGE being one of these. Often a main line which either has several PV installations on it or is near a main transformer with see voltages around the 250 – 253 volts AC. These are on the operating upper levels and surges above this voltage will either trigger a fault code or a an inverter to switch off (This will depend on the model and manufacturer but check the inverter specifications).

In the event that this is a common issue then it may be possible to adjust the tripping point on the inverter but this should be done in consultation with the manufacturer who will advise on the best parameters.

 

MODULE FAULTS often show up as a code on the display. This can be caused by either a damaged wire or connection or in rare cases moisture ingress into the module between the laminates that then short to the frame.  In this instance the module would need to be replaced and most will be replaced by the module manufacturer.

 

EARTH FAULTS can be difficult to trace and not always attributable to the inverter as there are many instances of faulty wiring or incorrect earthing within properties. Continuity checks are always the first test when this issue presents itself and a reassurance before replacing an inverter.

 

LOW GENERATION. This often caused by under estimation of the effect of shading or orientation but would not normally be below 10% of expected outputs. Bad connections on the DC can also effect the output therefore interrogate the display for the input DC voltages and power. Where there are 2 x MPPT it is possible to compare DC power but it is  important that the 2 arrays are facing in the same direction. Where there is on MPPT it may be necessary to make an assessment over a period of time and if possible (and not already done) connect the inverter to the web for long term data.

 

 

CHECK LIST

DC Switch ON

AC Isolator ON

MBB /RCCB ON

Inverter display ON

Error code or warning light

Interrogate display and check ALL parameters including voltage and power outputs for both MPPT’s

Where possible look at the inverter data online to check long term trends and performance.

When convinced that the inverter is at fault please check the warranty status and then contact the manufacturers service department or NuVision Technical Department.