Comprehensive set for measurements of photovoltaic installations – Sonel MPI-540-PV Solar

The Sonel MPI-540-PV multifunctional meter for electrical installations parameters has enormous measuring capabilities not only in the area of photovoltaics, but also of low-voltage recipient installations, power quality or – with the use of additional accessories – electromobility.

In PV installations, we can use it mainly for category 1 measurements as defined by EN 62446, such as:

continuity of protective connections,
resistance of ground,
insulation resistance on the DC side,
open circuit voltage UOC,
short-circuit current ISC,
operating currents and power on the DC and AC side,
inverter efficiency.

Photo 1. Measurements using the Sonel MPI-540-PV

Irradiance measurement with the Sonel IRM-1 meter

The EN 62446 standard indicates that all tests on the AC side of the recipient installation must be carried out before category 1 measurements can be performed. Their scope, in turn, is defined by the HD 60364 standard. The Sonel MPI-540-PV will also be useful in such cases. However, we can further enhance the meter's capabilities in photovoltaic measurements by adding an optional accessory – the Sonel IRM-1 insolation and temperature meter. With its help, we can measure the temperature of the photovoltaic panel or its surroundings and, above all, the level of solar radiation, i.e. irradiance. Measuring the irradiance and temperature of photovoltaic panels only will not tell us much about the condition of the photovoltaic installation. These are the parameters that define the prevailing environmental conditions around the measured panel. The Sonel IRM-1, thanks to its built-in compass and inclination sensor, is also able to determine the orientation and direction of the panels' exposure and their tilt. A built-in recorder enables all measured parameters to be recorded over an extended period of time. We can therefore use the device to diagnose the shading of panels in a particular location or to gather data to help design the installation. 5,000 memory records are overwritten during continuous operation, and PC software allows for downloading of measurements to be used for analysis or documentation. The device is mounted on the PV panel using the included set.

Photo 2. Sonel IRM-1 insolation and temperature meter

Sonel MPI-540-PV + Sonel IRM-1 = perfect combination

So how and why should you use the Sonel IRM-1 combined with the Sonel MPI-540-PV? First and foremost, some of the safety measurements taken with the popular combine require conversion to STC (Standard Test Conditions – 25°C, 1000 W/m²). Manufacturers of photovoltaic panels provide their basic parameters, such as the short-circuit current Isc, or the open-circuit voltage Uoc measured under these conditions. In order to compare measurements on the installation, the results must be converted to STC using appropriate formulas. These formulas include the temperature and insolation value at a given time. Of course, everything happens automatically and measured values from the Sonel IRM-1 are fed into the Sonel MPI-540-PV at the time measurements are taken. If you feed the panel parameters provided by the manufacturer into the database, the meter will also automatically convert to STC and give you a set of results for comparison.

Photo 3. PV installation measurements using Sonel MPI-540-PV and Sonel IRM-1

More than Bluetooth – Sonel LORA-S1

A Sonel LORA-S1 USB adapter is included in the Sonel IRM-1 set intended to cooperate with the multifunction meter, which – when installed in the USB socket of the multifunction meter – will enable communication between the two devices. LoRa Long Range) radio transmission protocol was chosen by the manufacturer for a good reason – it is much more reliable and works at much greater distances than the popular Bluetooth interface – up to 300 m. Wireless transmission also has an unquestionable advantage over communication via cable. We usually see a situation in which the electrical switchgear where we perform measurements is placed far from the photovoltaic panels themselves. The panels are often located on the roof of the building. Our solution allows for the results to be read on the Sonel IRM-1 in real time under almost any conditions. Even if there is an interruption of the transmission, data is automatically synchronised with the master meter shortly after recovery – thanks to the reSYNC function.

Together or separately – Sonel MPI-540-PV Solar

The offer of the Sonel company includes a dedicated Sonel MPI-540-PV Solar set containing accessories for PV measurements along with a Sonel IRM-1 insolation and temperature meter. The IRM-1 MPI insolation measurement set (WMPLIRM1MPI) can also be purchased separately if you own the Sonel MPI-540-PV model.

Author:
Tomasz Gorzelańczyk
SONEL S.A.