With the number of PV systems on the rise, it is vital to ensure that they are safe and comply with applicable regulations. Rob considers the role for dedicated meters such as the new Sonel PVM-1530 meter in ensuring safety standards are met.
The energy sector is transforming from a conventional and centralised model to a distributed model with the new approach heavily reliant on renewable energy sources, such as wind and PV power plants. In tandem with the installation of hundreds of thousands of microgeneration PV systems, large PV farms with substantial generation capacities are also being constructed.
The rapid increase in system numbers is not always matched by an increase in the quality of their components which can increase risks, reduce operational safety and shorten service life. This is why it is crucial for a system to be installed in line with applicable regulations and, once commissioned, to comply with all safety requirements.
Inspections, tests and measurements are essential in assessing the condition of PV systems. The primary assessment document is IEC 62446, a multi-part standard which defines the method and scope of safety checks for PV systems. Compliance with the standard’s guidelines ensures that the risk of shock or fire is reduced. IEC 62446-1 defines the tests necessary to check not only the safety of a system (Category 1), but also its efficiency and that of its components (Category 2).
Offering a range of tools for comprehensive testing of solar PV systems, Sonel has added the PVM-1530 meter to its portfolio which facilitates IEC 62446-1 assessments and is designed for the measurement of PV systems operating at voltages up to 1500V.
IEC 62446 procedures
Prior to making any measurements, a visual check of the PV system is vital to ensure that the electrical equipment has been correctly selected and installed, and that there are no visible irregularities or damaged components.
Once the visual inspection is complete, you can start to make the measurements. IEC 62446-1 divides testing into category 1 and 2 test procedures along with some additional tests.
Category 1 tests assess the safety of the system:
- Continuity measurement of protective connections and equipotential bonding with 200mA
- Polarity test
- Connection tests in DC junction boxes
- Measurement of the open circuit voltage of panels
- Measurement of the short-circuit current of a panel chain
- Measurement of the operating current
- Functional tests (measurement of DC and AC power on both sides of the inverter)
- Measurement of insulation resistance of DC circuits without short-circuiting panels
Category 2 tests
Recommended for larger and more complex solar PV systems, and can be performed once all Category 1 tests have been completed and passed. The Sonel PVM-1530 meter makes it possible to measure the I-U characteristics of panels with a maximum power of 45kW.
Additional tests enabled by the meter are:
- Blocking diode test with 1000V or 1500V
- Assessment of shading using the Sonel IRM-1 irradiance meter
Measuring I-V characteristics
I-V characteristics are very helpful in assessing PV system performance and identifying potential issues.
IEC 62446-1 specifies that irradiance must be at least 400 W/m2 for this type of measurement. IEC 61829 clarifies that the total in-place irradiance should be at least 700 W/m2 for measurements of characteristics to be extrapolated to STC (Standard Test Conditions).
PV panel manufacturers list parameters measured under laboratory conditions for STC: temperature 25°C, insolation 1000 W/m² and air mass factor AM 1.5.
For comparison purposes, the Sonel PVM-1530 can automatically convert measurement results to STC in accordance with IEC 60891. This is done with the Sonel IRM-1 solar and temperature meter, which works with the Sonel PVM-1530 wirelessly and with the built-in PV panel base.
A reliable solar PV system meter for professionals
The Sonel PVM-1530 and associated equipment comply with IEC 61557 and IEC 61010 safety standards and have the relevant CE declaration. IEC 61010-30 qualifies PV panels as belonging to the CAT III measurement category and, crucially, with its high CAT III 1500V DC measurement category, the meter can measure panels working at voltages up to 1500V.
Housed in a carrying case, the meter is IP67 rated when the lid is closed. Its advanced cooling system efficiently dissipates heat, enabling frequent measurements without overheating. A large, clear to read touchscreen enables easy operation and high brightness means it is visible even in full sunlight. The built-in Li-Ion rechargeable battery offers a long autonomous operating time, and an internal power supply unit makes it possible to simultaneously charge the battery and make system measurements if the battery fully discharges during operation.
With its comprehensive set of standard equipment, the Sonel PVM-1530 enables engineers and contractors to make the full range of measurements for PV systems in accordance with IEC 62446-1 to maintain them in good condition for many years.
Image credit: Power Quality Expert Ltd
