The individual sensitivity of a Kipp & Zonen radiometer is determined under the measurement conditions stated on its calibration certificate and is valid at the date of first use. If the radiometer is carefully stored in dark, warm and dry conditions and desiccant is changed as required, the sensitivity will not change. 

Many factors affect the measurement uncertainty of a radiometer under varying measurement conditions that differ from the calibration conditions, but the non-reversible effect on sensitivity is mainly caused by exposure to solar radiation. The physical properties of any optical radiometer change due to ultraviolet (UV) radiation affecting diffusers, optical filters, photodiodes, and the black absorber coating of thermopile detectors.

Kipp & Zonen specifies this ageing affect as ‘non-stability (change/year)’ and, in general, it will take about 2 years to noticeably affect the accuracy of measurements. It is for this reason that Kipp & Zonen recommends you calibrate your radiometers at least once every two years.

However, industrial customers using our products in testing, quality or process control (including solar energy) may have internal QA/QC procedures that require annual calibration. Certain industry standards, such as IEC 61274-1, Ed 2.0, July 2021 Photovoltaic system performance – Part 1: Monitoring, may also specify a two-yearly calibration interval.

Factory standard radiometer calibrations always nearby

For your convenience, Kipp & Zonen operates a network of centrally managed calibration facilities around the world that can also offer the most common pyranometer repairs.  The main office in Delft is ISO/IEC 17025 accredited for pyranometer and pyrheliometer calibrations.

Your advantages are:

• short turnaround times (5-10 working days, excluding shipment)
• instrument inspection, functional test and desiccant replacement included
• most common repairs can be done according to factory standards
• calibration fully according to factory standards, controlled by Kipp & Zonen head office, according to ISO 9847:1992 type IIc by professionally trained staff
• new calibration certificate and pyranometer label
• plug & play installation after calibration of SMP series smart pyranometers with sensitivity and calibration history updated in the instrument for direct use
• instrument calibration history available in central database to check reliability, stability trends and uncertainty.

In addition, our office in the USA can calibrate albedometers, most pyrgeometers and the CNR4 net radiometer; using the same equipment and procedures as at the factory.

Pyrheliometers, UV radiometers and some specialised products can only be calibrated at the factory.

For information and quotations regarding calibration contact your local calibration point.