Solar PV Testing

Whatever your solar PV testing needs are, we have you covered.

We've been manufacturing solar PV testing solutions for nearly a decade and have become a trusted name within the industry. Whether you are a residential, commercial or utility scale PV installer, or testing 1000V and 1500V installations, we have a PV testing solution for you.

WHAT IS SOLAR PV TESTING?

The term photovoltaic (PV) refers to a system that uses semiconductor materials to convert light into electricity - resulting in a Photovoltaic Effect.  PV systems come in varying sizes and formats, so an understanding of PV components and how they are used is needed before PV testing can be performed.

A basic PV system consists of the following:

PV module, could be one or many modules that are linked together to form a PV array. Modules connected in series are called strings. The role of a PV module is to convert the light energy from the Sun into DC electrical energy using semiconductor materials. Some systems can be optimized (DC optimizers) to compensate for shading of the PV modules, an effect that can greatly reduce system performance.

Inverter, converts the DC output from a module into AC electricity. The output of an inverter can be fed to a storage system, a load centre, or both.                    

AC Modules are a combination of both the PV module and inverter in one unit. These components use microinverters, which are small inverters attached to the back of the module, to produce AC electricity directly from the PV module.

In addition, more complex PV systems can incorporate combiner boxes (to take multiple strings), fused connectors, ground (Earth) fault protection, charge controllers (voltage regulators) and switchgear etc.

PV testing is carried out by qualified PV technicians / PV engineers, many of whom are qualified electricians. Testing can be carried out at various stages, for example, at the pre-installation stage (testing of individual modules), while commissioning (where the system is being installed) or during the ongoing operation and maintenance stage (to ensure the PV system integrity and performance is maintained).

WHY DO WE TEST SOLAR INSTALLATIONS?

Solar PV systems have been, and are being, installed in vast numbers all over the World. Such systems are expected to perform for decades, but also during this period, operate safely. Unfortunately, many PV systems have not been correctly installed or placed into service with little ongoing maintenance, which ultimately leads to a loss in potential revenue from the installation but could be a danger to life.

Due to the nature of where they are installed, PV systems can be prone to extreme environmental conditions and therefore it is particularly important to make sure any system deterioration is detected and controlled or rectified.

All PV systems should be tested for safety and performance conformation. However, the category of testing depends on local regulations, system designers and the ability of the commission engineers.

Consideration should be made for changes to the PV system or its surroundings. For example, many PV installs are on roof tops and maintenance to the building structure may be required. Also, over extended periods, additional building or electrical works may appear in the vicinity of the PV array.

HOW DO WE CARRY OUT SOLAR PV TESTING?

Unlike most other electrical systems, the DC side of PV cannot always be switched off or made dead to allow electrical testing to be performed – you cannot switch off the Sun. In any case, certain electrical tests require irradiance data (Solar power per unit area) to be considered as part of the testing procedure (when comparing to Standard Test Conditions, STC).

Verifying any electrical system generally falls into two parts; the first, a visual inspection, which should be performed before any of the electrical testing is undertaken.

A visual inspection can help to ensure there are no problems with the PV system, for example, damage to the modules, cable connectors, wiring or other PV components such as invertors or combiner boxes. Visual inspection should happen, not only as part of the commissioning process, but also, during periodic testing.

If we consider AC testing, AC Modules, micro-inverters or DC optimizers as beyond the scope of this article, we need to consider electrical testing of the DC side of a PV system. This testing, however, falls into two categories; System Testing and Measurement and System Performance Testing.

1, System Testing and Measurement; testing of the DC side of a PV system generally incorporates the following;

Continuity testing, or resistance testing, is undertaken to verify the integrity of the protective earth, grounding or equipotential bonding conductors and connections.  Correct grounding / earthing of a PV system is required to reduce the risk of electrical shock to personnel. Please note, not all PV systems, especially small older systems, are grounded or earthed.

Polarity testing is required to ensure correct connection to other components in the system such as inverters, charge controllers or batteries where cross polarity can result in a loss in efficiency as a minimum, but at worst, be extremely dangerous.

Voltage and current testing is performed to verify the PV system is operating within the design specifications. The Open Circuit Voltage (Voc) and Short Circuit Current (Isc) are commonly used to confirm these characteristics.

Insulation resistance testing is used to identify faults to the insulation by testing the integrity of wiring and equipment.

Functional testing ensures items such as switchgear and other control devices, are mounted, connected and operating correctly.

2, System Performance Testing;

Performance testing of PV systems is required to ensure the PV system is operating according to the system design. This generally involves voltage and current measurements and can include I-V Curve tracing. Comparison to Standard Test Conditions (STC) must be performed which takes into consideration the temperature, irradiance and spectral data (at the time of measuring) and, when combined with the electrical measurements, is used to verify the power and energy of the PV system and enables comparison to manufacturers specifications.