Last update 25 JUL 2022

Photovoltaic and Thermopile Pyranometers: Let’s get some clarity on reference standards

Pyranometers are devices used to measure solar irradiance. According to the operating principle, we distinguish the Thermopile Pyranometers from the photovoltaic one. The latter is called too photovoltaic cell pyranometer, irradiance sensor or reference cell. Each instrument has to follow specific regulations and metrological references.

Photovoltaic Pyranometer: standards rules

For this specific kind of Pyranometer it is necessary to make a differentiation between the referred standards up to 2009 and what entered subsequently into force.
We have to take into account too that up to the first years of the new Millennium the Photovoltaic Pyrometers cells were on the market inaccurate due mainly to two defects. Their measurement is influenced by cell’s temperature and aging. By the way, the best irradiation sensors don’t present these two defects since a long time. In addition, the analyses carried out by photovoltaics research institutes led in 2008 to the creation of the IEC60904 family of standards. It regulates the construction, traceability and calibration of reference cell. While IEC60904-2 regulates manufacturing procedures and calibration, IEC60904-3 determines measurement principles and the solar spectrum reference.

Thermopile Pyranometer: standards rules

Thermopile Pyranometers widespread since the first half of the last century. That is why there were standards already in the ‘90s. For that period the reference standard was ISO9060:1990: it determined specifications and classifications. In 2018 the latter was replaced by ISO9060:2018. It added sensors with other technologies and reclassified Pyranometers into A, B, C classes, based on their accuracy and response speed. About calibration the standard is ISO 9847.

Reference standards for Photovoltaic Pyranometers and Thermopile Pyrometers in PV fields.

In addition to the above standards, big photovoltaic systems companies refer to IEC61724-1. It specifically describes the terminology, appliances, methods and metrology to monitor performance and analysis of photovoltaic systems.
By the way this standard is already at its 3rd edition: the main changes have focused on a greater precision and they preferred pyranometers thermopile. Even if its constructive characteristics lead it to be a less accurate instrument for the measurement of the P.R. compared to a photovoltaic pyrometer, that better represents a photovoltaic module under optimal conditions.

Indepths, soon in a Document on our website currently only in Italian.

Soluzione Solare for both pyranometer technologies complies with the above standards and quality management system certified ISO 9001:2015.