Extending the Spectrum Characterisation of Solar Simulators from 300 nm to 1200 nm: Challenges on Spectral Measurements in the UV and NIR

Innovative photovoltaic technologies with spectral sensitivity exceeding the 400 to 1100 nm limits (as currently defined by the international standard IEC 60904-9) are nowadays available on the market. This poses new challenges in the correct measurement of the spectral content of solar simulators and natural sunlight in those wavelength bands that lie outside these limits. This study proposes an extension of the IEC 60904-9 bandwidth by adding two bands in the UV (300-400 nm) and NIR (1100-1200 nm) regions. This new proposed extension is analysed in terms of spectral match, using spectral measurements of Global Normal Irradiance (GNI) acquired during the 6th European Spectroradiometer Intercomparison by eight independent laboratories. A laboratory is selected to provide reference spectra, and the spectral match of the other ones is calculated, both on a single-measurement level and on a daily average level. The intra-day and inter-day variations are evaluated as well. Results show that all investigated laboratories are capable to assure a spectral match well below the ±25% limit corresponding to class-A simulators. When the more stringent, informal class-A+ corresponding to the ±12.5% limit is considered, four out of seven laboratories are still compliant with it.JRC.C.2-Energy Efficiency and Renewable

Spectroradiometry in PV: how inter-laboratory comparison may improve measurement accuracy

Spectroradiometry is a key metrological discipline for accurate testing of photovoltaic (PV) devices, particularly relevant both for indoor testing on solar simulators and for outdoor testing, where differences between the available thermal energy and the energy usable by PV modules are relevant. In fact, as to indoor testing, the uncertainty in the spectral mismatch between the testing light source and the reference spectral irradiance may give rise to deviations up to 1-3% when measuring the maximum power even on a Class A solar simulator. Experimental uncertainty is expected to increase even further after the publication of the new revision of IEC 60904-9 (“Solar simulator performance requirements”), which is due by 2018. As to outdoor testing, accurate knowledge of solar spectral irradiance is important also for energy rating purposes, in view of the publication of IEC 61853 part 3 (“Energy rating of PV modules”) and part 4 (“Standard reference climatic profiles”). The relevance of accurate measurements of solar spectral irradiance has led the most renowned accredited European solar PV test centres to take part to a series of International Spetroradiometer Intercomparisons that has taken place every year so far since 2011 in various localities in the Mediterranean Basin. The ever-growing number of participating laboratories is both a consequence and a key of success of the whole exercise: ISO 17025 accredited laboratories are willing to receive confirmation of the stability and accuracy of their spectroradiometers and that can be done only when a conspicuous number of testing centres is involved. This paper summarizes the outcomes of the last intercomparisons, trying to highlight whether improvements in measurement reproducibility can be inferred from those partners that have participated since the earliest editions. The work gives new insights into spectroradiometry for both outdoor and indoor testing applications.JRC.C.2-Energy Efficiency and Renewable