A Comparison of Photovoltaic Test Equipment

The challenge

A range of PV testers are available on the market, but most solar PV test instruments are designed for IEC certification, efficiency testing, or Infra-Red imaging. The problem is that only very few instruments are designed for operations and maintenance or even troubleshooting. This neither good or bad, this is just the status in a solar energy market which is maturing and consolidating into an agenda focused on operations and long terms financial wins. Standard meters are often used for complex testing and troubleshooting, but this approach requires dismantling of PV systems, and rigorous “divide and conquer” approaches. The end result is ineffective troubleshooting, that requires many hours spend in the field and many truck rolls in vain. It all has a negative impact on the long term return on investment.

How to test solar panels for faults

Instrument categories

IV Curve tracers

I-V curve tracers are specialist types of test equipment that sweep an electrical load connected to the solar PV module or string and measure both the current and voltage at multiple points during the sweep. This procedure will under optimal weather conditions allow to deduce the conversion efficiency of the PV array.

Thermal Cameras

Thermal camera capture and create an image of an object by using infrared radiation emitted from the object in a process that is called thermal imaging. The created image represents the temperature of the object. In PV these devices are used to detect hot spots in the PV system when the it is fully energised.

String Tester

String Testers usually carry out electrical tests as required by the IEC 62446 standard. The devices will record irradiance and temperature while also testing electrical parameters such as voltage, current and isolation resistance.

The Z200 PV Analyzer

The Z200 PV Analyzer is designed entirely for troubleshooting and diagnosing strings of PV modules in the field. The instrument is different since it can measure the actual position of faults. Also it will detect early signs of degradation. The philosophy is to help field technicians, and to improve the cost efficiency in PV operations and maintenance.

Advantages and user benefits with the Z200 PV Analyzer

When it comes to troubleshooting solar power plants, there are often very high expectations put in the technicians. They must first collect data in a dangerous environment and hereafter make correct conclusions, that can correctly point out the origin of a problem in the field.

Our attitude is that using inadequate test equipment for this task, while also expecting flawless results, is not the best way to increase the economy of a photovoltaic power plant. We can cite Rita Mae Brown (1983, book: “Sudden Death”) and state that: Insanity is doing the same thing over and over again, but expecting different results. In the same way we experience a wish to increase the return on investments, but still for too many companies rely on non automated fault finding methjods in the field of photovoltaics. A schematic representation of various applications of the 4 different instrument categories is shown below.

The basic theme in question is: Application! What is the purpose of the field work? Testing for performance and safety are just some of the potential reasons to go to the field. In a market where more and more focus is on troubleshooting and maintenance, it is important to consider the capability of the equipment you intend to use. Only by doing so, will you be able to build up and maintain adequate tempo and efficiency, that leads to overall improvement in the PV system economy.

Photovoltaic testing equipment
A comparison chart showing the 4 main categories of photovoltaic field test equipment: IV curve tracers, String Testers, Thermal Cameras and the Z200 PV Analyzer.