Maintenance services

Maximising the profitability of your investment

Despite having no moving parts, a PV system needs to be inspected at regular intervals to ensure smooth operation. Generally this involves annual detailed visual inspection, cleaning and electrical testing.

Often there may be no immediate visual cues to indicate if there is a fault with a PV system, so it is important to monitor the output to ensure it is functioning correctly.

If there is something wrong, time is of the essence, since any period of inactivity represents irreplaceable lost revenue.

During maintenance visits we frequently find systems installed by others with strings disconnected or that have been running below their optimum output for long periods of time.  These situations lead to totally avoidable loss of income.

Gary Haines Director of Operations
Gary Haines: Director of Operations

Operation and Maintenance

The first stage is a site visit for an initial inspection, which is free of charge.  Once we have a clear idea of the equipment on site and its condition we will then follow up with tailored proposals designed to help you get the most out of your system.  NWT’s Operation & Maintenance package will ensure that any future issues are identified and repaired as soon as possible.

See “Our Projects” for examples of the kind of issues we have encountered.


Electrical testing and inspection is an important aspect of the Operation and Maintenance services because it allows us to reduce the risk of any system down time by ensuring that any minor issues are identified and rectified early.

Electrical testing is concerned with checking physical connections for loose contacts or signs of wear. This is a fire prevention measure and also stops the system from tripping, which can lead to long periods of inactivity or frequent gaps in generation.

Measuring insulation resistance also gives an important indication of whether further electrical issues may be present. At the end of the tests we issue you with a full testing and inspection report, along with a “traffic light” list that covers any issues we find and classifies them in order of how urgent they are. The following inspections will take place at each site visit:


General site inspection

  • Check for vegetation growth or other new shade items.
  • Check for ground erosion near the footings of a ground mount system.
  • Confirm proper system signage is in place.
  • Check for corrosion on the outside of enclosures and the mounting system.
  • Check for cleanliness throughout the site.  There should be no debris in the inverter area or elsewhere.
  • Check for displaced wires and cabling.
  • Check for signs of animal infestation under the array.


Detailed visual inspection

A visual inspection will include the following actions:

  • Inspect the inverter to make sure it does not show signs of cracking or excessive wear. The inverter should be bolted to the wall at all mounting points per the manufacturer installation requirements. Depending on the size, location and accessibility of the system, the inverters and combiner boxes should require tools to prevent unauthorised access to the equipment.
  • Inspect roof drainage is adequate, roof drains are not clogged, and confirm that there are no signs of water pooling in the vicinity of the array.
  • Inspect PV modules for defects that can appear in the form of burn marks, discolouration, de-lamination, or broken glass.
  • Check modules for excessive soiling from dirt build-up or animal droppings.
  • Inspect mounting system for defects including rust, corrosion, sagging, and missing or broken clips or bolts.
  • In roof-mounted systems, check the integrity of the penetrations.
  • Inspect all system isolation points, and look for signs of corrosion or damage.
  • Check to make sure the cabinet penetrations are properly sealed and there is no evidence of water ingress.
  • Perform a visual inspection of the interior and exterior of the inverter. Look for signs of water, rodent, or dust intrusion into the inverter.

 Manufacturer-specific inverter inspection

Each inverter manufacturer will have specific requirements for inspection, testing, Services, and documentation to meet its warranty obligations.  Typical requirements or inverter inspections include:

  • Record and validate all voltages and production values from the display.
  • Record last logged system error.
  • Clean the inside of the cabinet.
  • Check seals.
  • Confirm warning labels are in place.
  • Look for discolouration from excessive heat build-up.
  • Check integrity of surge arrestors.
  • Check mechanical connection of the inverter to the wall or ground.
  • Check internal disconnect operation.
  • Verify that current software is installed.
  • Contact installer and/or manufacturer about any issues found.
  • Document findings for all work performed.
  • Continuity of the equipment earthing at the inverter, combiner boxes, and isolators.
  • Continuity of all system fuses at the combiner boxes, isolators, and inside the inverter(s).
  • Open-circuit voltage (Voc) of all strings with the inverter off; and
  • Maximum power current (Impp) of all strings.

(Used when problems are identified or required by contract terms)

May include:

  • Thermal images of combiner boxes (opened and closed), isolators, inverters (external and internal at a specified operating point), and modules.
  • Short circuit (Isc) testing of strings.
  • Insulation resistance test of conductors at specified voltage.

Inspection after