FAQ – Frequently Asked Questions
Frequently Asked Questions
We’ve collected the most common questions from our users
Here you’ll find the answers to the most common questions.
Can the PVPM1540X also be used for measurements on bifacial PV modules?
Yes, the PVPM1540X has been specifically designed for the precise measurement of high-efficiency and bifacial PV modules. Thanks to its modern electronics and high current capability, the device is ideally suited for modules with large short-circuit currents and capacitive characteristics, which are common in bifacial technologies.
For a complete evaluation of bifacial modules, the PVPM1540X supports the measurement of irradiance on both the front and rear sides. Up to three PV reference cells can be connected, with their signals processed by the device and displayed in real time.
In combination with the Curvealyzer software, the measurement data can be graphically analyzed, processed, and documented – including automatic report generation.
With the PVPM1540X, the actual performance of bifacial PV modules can be determined precisely and reproducibly, both in the laboratory and under real outdoor conditions.
How often should a PV measurement device be checked and calibrated?
The frequency of calibration of a PV measurement device is generally at the user’s discretion and depends on the operating conditions, level of use, and internal quality requirements. According to the relevant standards for photovoltaic measurements – for example, DIN EN 60904-1 (equivalent to IEC 60904-1) and DIN EN 60891 – an annual calibration interval is considered appropriate and practical.
For this reason, we recommend an inspection and calibration once per year. This service can be ordered directly from PVe and includes, in addition to standard-compliant calibration, a functional test, safety inspection, and measurement verification.
This ensures that your device remains fully operational, accurate, and safe at all times.
What does the annual inspection of a PVPM measurement device at PVe include?
For long-term measurement accuracy and operational safety, PVe recommends having each PVPM device undergo a comprehensive annual inspection by the manufacturer. This inspection ensures the standard-compliant performance of all measurement, safety, and system components.
As part of the annual inspection, the entire measurement system is carefully checked. This includes:
Visual and functional inspection of the main PVPM device
Inspection and testing of all accessories such as measurement cables, sensors, adapters, and connectors
Recalibration of measurement inputs
Electrical safety test in accordance with the applicable regulations
Issuance of a calibration certificate with documented measurement values and test report
Firmware update to the latest version (if required)
Cleaning and inspection of control surfaces
The annual inspection can be ordered directly from PVe. It ensures that the PVPM device continues to perform precise I-V curve measurements up to 1500 V and that all safety functions operate correctly.
How often should an irradiance sensor or reference cell be checked and calibrated?
For irradiance sensors and PV reference cells, the appropriate calibration interval depends on the operating conditions, environmental influences, and the user’s quality requirements. For precise and reproducible measurement results, the relevant standards – in particular DIN EN 60904-2 (equivalent to IEC 60904-2) – recommend a regular verification and calibration approximately once per year.
PVe therefore recommends having reference cells and irradiance sensors calibrated once a year to prevent measurement deviations caused by aging or contamination of the sensor surface. Calibration can be carried out directly by PVe and also includes a visual and functional inspection.
How should a PVPM device be properly packaged for shipping?
For safe transport, we recommend keeping and reusing the original PVe shipping packaging. It is perfectly matched to the device and provides optimal protection.
Since sustainability is important to us, we use recyclable cardboard packaging that is stable, durable, and reusable. If the original packaging is no longer available, please use a sufficiently large box and secure the device with at least 5 cm of cushioning material on all sides. The device must not be shipped loosely or only in the transport case with a shipping label attached.
For frequent transport, we also offer robust PVe transport cases – durable, stable, and ideal for worldwide use.
I would like to learn more about the background of I-V curve measurement.
Are there any publications available on this topic?
There is a wealth of information available on this topic. We would like to recommend the book Photovoltaic Engineering – Handbook for Planning, Development and Application by Prof. Andreas Wagner. Also very informative is the book “Simulation of Shading Losses in Solar Electric Systems” by Prof. Dr. Volker Quaschning. More details about this book can be found here.
How does the import and export process work for service or repairs of a PVPM device?
Shipping a PVPM device for repair is easier than you might think. PVe has many years of experience in international shipping and is happy to assist you with the import/export process.
To ensure a smooth process, we kindly ask you to coordinate and register any return shipments with us in advance. This allows us to prepare all customs and shipping documents correctly and ensure fast processing.
For customers within the EU and also worldwide, our authorized PVe partners are available to assist with shipping, handling, and on-site service.
This keeps the entire repair process simple, safe, and efficient – no matter where you send your device from.
The measurement cables of PVPM devices always consist of multiple conductors. Why is that?
PVPM devices measure both voltage and current at the solar generator. When current flows through a measurement cable, part of the voltage drops due to the cable’s resistance. This would always result in a voltage reading that is too low. To avoid this, a so-called four-wire cable is used: one pair of conductors carries the current, while the second pair measures the voltage. Since almost no current flows through the measuring pair, the voltage remains unchanged – ensuring the high precision required.
The devices of the PVPM series are quite large. Can’t they be made smaller?
We have compelling reasons not to reduce the size: the critical factor here is measurement speed. With a capacitive load, the relationship is clear: the smaller the device, the faster the measurement. However, the faster the measurement, the more errors occur, as capacitive and inductive effects from the PV generator and cabling distort the actual results. For us, the quality and precision of the measurement are far more important than housing size. That’s why PVPM devices are built in the proven format.
The devices of the PVPM series come with a reference sensor and connection cable.
Wouldn’t wireless data transmission be more practical?
A wireless connection of the reference sensor would indeed be easier for the user. However, it also has a major drawback: wireless transmission requires a protocol that takes time. Since solar irradiance can change significantly within milliseconds, precise I-V curve measurement demands that irradiance is captured exactly at the same moment as the curve. For this time-critical measurement, a cable connection is essential to guarantee accuracy. In addition, a cable link can be an advantage in certain situations – for example, when no reliable wireless connection is possible due to distance or shielding conditions.
Does PVe also offer the rental of PVPM measurement devices?
Yes, PVe offers the rental of PVPM measurement devices – ideal for customers who need a device temporarily or wish to carry out specific measurement tasks.
Many providers avoid offering rental devices because they must be regularly tested and calibrated. PVe deliberately takes on this effort to always provide professionally maintained and ready-to-use equipment.
All rental devices are fully inspected, calibrated (if required), and functionally tested before each rental period. A special advantage: rental fees can be credited toward the purchase of a new device at a later date.
So bleibt Ihr Projekt flexibel, wirtschaftlich und technisch auf höchstem Niveau.
Can I connect other reference sensors to the PVPM devices?
You can connect any irradiance sensor to the PVPM that delivers a voltage proportional to irradiance: 0 mV at 0 W/m² and between 10–100 mV at 1000 W/m². The connector on the PVPM is a standard component – you can request the exact designation and pin assignment from us. This flexibility is especially important when measuring modules that are not based on mono- or polycrystalline cells. According to EN 60904, the reference sensor must have the same spectral characteristics as the module under test – meaning you need a matching sensor. For all common technologies, suitable reference sensors are available and can be connected to the PVPM.
Are additional devices required for measurements with the PVPM?
No, PVPM devices work completely independently. Everything you need is already included: the measuring device with its own battery, the reference sensor, connection cables, and the safety load disconnector. With power supply, computer, and graphic display integrated, you are ready to work on site right out of the box.
What is the benefit of knowing the Rs (series resistance) value?
The series resistance Rs is an indicator of the quality of the PV generator’s cabling. Issues such as connector corrosion, cable damage, or undersized wiring will increase Rs beyond the expected value for the module. Since manufacturers usually do not specify Rs, you can calculate it with the PVPM.disp software included with every PVPM device. If the measured Rs is higher than the calculated value, the cabling should be checked for faults.
