Solar PV Testing and Analysis

Engaging CPS National as your asset management partner provides you with the security and continuity of technical support from a large Australian owned company. We are committed to ensuring your equipment operates as designed, remains in service and is statutory compliant.

As part of Ampcontrol Group we can carry out the following services:

  1. Aerial thermography
  2. Ground thermography
  3. Switchboard thermography and HV switchyard thermography
  4. Onsite Electroluminescence testing
  5. Site image mapping
  6. IV curve tracing
  7. VOC testing
  8. Ground fault testing and fault finding
  9. AC analysis temporary or permanent solution with integrated software
  10. AC fault analysis with integrated software
  11. AC low voltage testing
  12. AC high voltage testing
  13. MV/HV transformer testing
  14. Ring main unit testing
  15. Oil testing
  16. Relay injection testing
  17. Onsite rectification
  18. O&M solutions

Assigning ongoing analysis and rectification of your electrical assets to CPS National provides the assurance of optimum performance and availability.

For more information on CPS National’s Solar PV Testing and Analysis services, contact us.

solar pv testing drone IR imaging
Download Commercial Solar PV Testing Brochure
Download Solar Analysis and Rectification Brochure

Understanding the health of your system

As can be expected, different components and faults require different tests to ascertain their condition. The below outlines some of the main tests and analysis undertaken by CPS National to ensure system health and maximum output.

Electroluminescence (EL) Testing

EL testing utilises electroluminescence imaging. CPS National have developed both onsite insitu and factory/workshop imaging capabilities.

EL testing detects hidden defects in the structure of the PV cell. This capability allows both EPCs and manufactures to verify a number of issues that may not be identifiable otherwise, including:

  1. Microcracks
  2. Grid finger interruptions
  3. Snail trails
  4. Over tightened panels
  5. Damage from hail
  6. Damage from mishandling
  7. Potential induced degradation (PID)

Arial and ground based solar panel thermography

By using infrared cameras, both hand-held and drone mounted, thermal images can gathered from a wide range of angles and vantage points, creating a detailed map of the solar module health.

Thermal imaging can identify a range of issues including:

  1. Interconnection issues
  2. Hotspots
  3. Complete panel failure
  4. Soldered connection failures
  5. Defective Cells
  6. Identify de-energised systems
  7. Internal short circuits

I-V curve tracing

I-V curve tracing is an electrical test of photovoltaic performance. Focussing on a single string at a time, I-V curve tracing measures current and power as a function of voltage. This measure is compared to the expected result and can therefore immediately identify a problem, right down to the specific wire, connector or module within the string.

The immediacy of I-V curve testing means technicians can identify and repair issues in the field. In addition, such tests can generate comprehensive reports on the condition and performance of the system.

Benefits include immediate issue identification and repair, creating system baselines, warranty claim data and detailed reporting.

I-V refers to:

I: the short-circuit current (Isc) which is the current through a solar cell when the voltage across the solar cell is zero;

V: the open-circuit voltage (Voc), this is the voltage that is read with a multi-meter when the module is not connected to any load. You would expect to see this number listed on a PV module’s specification sheet.

Voc testing

Open-circuit voltage (Voc) is the voltage that is read with a multi-meter when the module is not connected to any load. You would expect to see this number listed on a PV module’s specification sheet.

Ensuring accurate Voc in the solar modules is crucial in avoiding over voltage and damaging electronics.

Tests on a live site can be performed when voltage is produced in the morning when the sun first comes up and the panels are at their coolest, but the connected electronics haven’t woken up out of sleep mode yet.

Switchboard and HV switchyard thermography

Handheld or ground infrared can measure all areas of electrical components to assess for any hotspots. Used much like drone IR but employed for items like DC combiner boxes, connectors, AC switchboards and inverters.

Gloss Meter Reading

Gloss reflectance meter readings helps determine the reflectance on the panels prior to carrying out drone infrared scanning. Measured in Gloss Units (GU), it provides an initial reading prior to cleaning, and a follow up reading post clean to compare. Doing this assists with the drone infrared calibration. If there is excessive soiling on the panels, the reflectance of heat may be hiding hot spots.

Battery Maintenance

Battery maintenance plays an important role in any hybrid or off grid systems. Battery energy storage systems affect the efficiency of solar PV systems as excess energy created through the day is stored and dissipated through the night.

Regular discharge testing including voltage and impedance readings are recorded to test the integrity of each cell.

DC Testing

With the string voltages pushing towards the HV limit of 1,500VDC, a good understanding of the dangers of DC electricity must be taken into consideration.

Faults can occur in mismatched connector type, cheap connectors, loose terminals in combiner boxes, insulation damage due to stainless steel cable ties not being installed with the right tools and a variety of other factors.

AC Testing and Fault Finding

AC testing and fault finding is performed by specialist trained electricians, and ranging from low to high voltage. HV asset testing also makes up an important part of a full regime, including substations and transformer oil and electrical testing.

A Panel Testing Timeline

  1. The Manufacturer
    By utilising cross border partners, testing can potentially begin at the manufacturers premises. Panel manufacturers state their STC results as part of the supply process. These results can be verified prior to the panels leaving the site.
  2. Post Transport
    If a batch of panels has left the manufacturer in good condition, there still remains opportunity for damage in the logistics phase. Post transportation testing can verify no adverse effects in transport.
  3. Post Installation
    Fixing panels to ground mounts or other structures is a predominantly manual task that if not undertaken in a considered manner can result again in panel damage. Sample testing after installation is another insurance level in the supply chain.
  4. Ongoing and Periodic Testing
    Adverse weather such as hail, cyclones and strong winds can result in panel damage. In addition, abnormal panel deterioration may occur. Periodic testing and documenting can mitigate the risk of poor panel performance, and highlight developing problems.

What is solar PV?

Solar PV (photovoltaic) refers to the collection of photons from the sun that are then converted into energy by a process called the photovoltaic effect.

This particular solar technology utilises solar cells generally constructed of silicon acting as a semiconductor. Sandwiched between conductive layers, the silicon atoms are bonded in such a way that prohibits the flow of current. By having two separate layers within the silicon cell, the electron movement leaves one layer positively charged, and one negatively charged.

As photons hit the silicon cells, they can knock electrons loose. An electric field between the silicon layers then directs the electrons through thin metal conductor strips.

This part of a solar energy system is referred to as the solar module.

From this point, a more standard or traditional system organises the available energy into usable and distributable electricity.

The main components of a solar energy system

To make up a full solar PV system, the linking of solar modules creates capacity.

Solar panels, or modules, are linked together by wires in what is called a string. At this point, junction boxes are used to combine all the wires from the string, before the main cable then runs to an inverter.

The inverter converts the electrical voltage from DC to AC and passes it through to a low voltage switchboard.

In the case of larger systems and solar farms, a HV switchyard then steps up the voltage with the use of transformers, and distributes the power into the electrical grid.

Efficiency and system losses

Solar photovoltaic (PV) systems are becoming more prevalent across Australia and the world, and efficiencies and technologies continue to develop however, most commercial solar cells are only about 15-20% efficient.

This does not necessarily constitute 80% lost energy, as the systems are designed with this in mind. It does however highlight the need to ensure peak capacity within the designed system itself.

So where can losses and inefficiencies occur? The answer is right across the system from the cells themselves to the electrical distribution system, both being susceptible to degradation and things going wrong.

These include damage to panels that may or may not be seen by the naked eye, poor wiring, bad connections, inverter component break down, switchboard and circuit breaker connections, SCADA monitoring issues, transformer oil degradation, and transformer wiring. All these can succumb to harsh Australian conditions.