European project leads to new standard for photovoltaic classification
European researchers developed a new classification system for photovoltaic (PV) devices, which can be used to reliably estimate their efficiency under real operating conditions.
The findings of the EURAMET ENG55 PhotoClass Project, which involved a consortium of six European National Metrology Institutes (NMIs), the Scuola Universitaria Professionale della Svizzera Italiana (Switzerland), TÜV Rheinland Energy GmbH (Germany) and the European Commission’s Joint Research Centre (JRC) have been recently published in the project’s final report and have led to the new IEC 61853 standard. Its application will help governments and industry to make informed decisions and invest more wisely, by reducing the uncertainty due to the inappropriate standard test conditions which were used previously.
PV devices are made up of solar cells that use the properties of semiconductor materials to convert energy from the sun into electricity; since they operate without generating any greenhouse gases or pollution, they have rapidly been adopted as a viable, renewable energy source.
PV devices are currently sold according to their output power under fixed standard test conditions. These conditions represent a cloudless sunny day in the middle of the USA, with an unrealistically low device temperature of 25°C. The real climate almost everywhere in Europe is significantly different and, since the device efficiency varies with the environmental conditions, output power estimates done with this metric often do not correspond to the energy generated under real operating conditions.
Decisions on how to invest public (government) and private (industry/consumers) money on PV installations were also made based on power efficiency numbers that do not correlate with the real energy output under operational conditions. Since the world market for PV devices approximately amounts to 50 billion Euros per year, being able to reliably predict the real energy output of a PV installation during the planning phase could generate global yearly savings of several hundred million Euros.
The consortium set out to solve this problem by developing a new classification metric that is not based on the peak power but rather on different standardised climate zones. Therefore, hourly irradiance and weather conditions had to be extracted out of satellite and ground based data for a standard year and for a representative place for each climate zone. Using the calibration capacities built up within the project, the solar device properties, required for the new metric, can be determined. Once the relevant parameters for a particular device are known, they can be used to predict its expected energy yield in any climate zone.
A three-day training course was hosted at JRC Ispra from 5-7 April 2017 on best practice for PV measurement procedures. This training course was attended by members of the scientific community from higher education and public research organisations and was highly praised by the participants.
The facilities and measurement methods developed at the JRC during the project have in the meanwhile been implemented in the laboratory quality system and are available for researchers and customers.