Results of the fifth international spectroradiometer comparison for improved solar spectral irradiance measurements and related impact on reference solar cell calibration

This paper reports on the results of the fifth spectral irradiance measurement intercomparison and the impact these results have on the spread of spectral mismatch calculations in the outdoor characterization of reference solar cell and photovoltaic (PV) devices. Ten laboratories and commercial partners with their own instruments were involved in the comparison. Solar spectral irradiance in clear sky condition was measured with both fast fixed and slow rotating grating spectroradiometers. This paper describes the intercomparison campaign, describes different statistical analysis used on acquired data, reports on the results, and analyzes the impact these results would have on the primary calibration of a c-Si PV reference cell under natural sunlight

Second international spectroradiometer intercomparison: results and impact on PV device calibration

This paper describes the results of an intercomparison of spectroradiometers for measuring global normal incidence and direct normal incidence spectral irradiance in the visible and in the near infrared, together with an assessment of the impact these results may have on the calibration of the short circuit current (I-sc) of triple-junction photovoltaic devices and on the relevant spectral mismatch calculation. The intercomparison was conducted by six European scientific laboratories and a Japanese industrial partner. Seven spectroradiometer systems, for a total of 13 different instruments/channels using two different technologies and made by four different manufacturers were involved. This group of systems represents a good cross section of the instrumentation for solar spectrum measurements available to date. The instruments were calibrated by each partner prior to the intercomparison following their usual procedure and traceability route in order to verify the entire measurement and traceability chain. The difference in measured spectral irradiance showed to have an impact on the calibration of a set of Iso-Type cells varying from +/- 2% to +/- 14% for middle and bottom cell, respectively

Second international spectroradiometer intercomparison: preliminary results and impact on PV device calibration

This paper describes the preliminary results of an intercomparison of spectroradiometers for global (GNI) and direct normal incidence (DNI) irradiance in the visible (VIS) and near infrared (NIR) spectral regions together with an assessment of the impact these results may have on the calibration of triple-junction photovoltaic devices and on the relevant spectral mismatch calculation. The intercomparison was conducted by six European scientific laboratories and a Japanese industrial partner. Seven institutions and seven spectroradiometer systems, representing different technologies and manufacturers were involved, representing a good cross section of the todays available instrumentation for solar spectrum measurements

Results from the Second International Module Inter-comparison

Most photovoltaic (PV) manufacturers trace their peakwatt rating through calibrations/measurements performed at recognized terrestrial calibration facilities. This paper summarizes the results of one such measurement performed by many different calibration facilities. The participants were selected from around the world based on their designation as a national PV calibration facility, prior participation in inter-comparisons, or as an ISO 17025-accredited PV module qualification or certification facility. Each facility was sent the same devices and was requested to treat them as a regular measurement. The modules were selected from newer thin-film manufacturers - ones that might stretch or exceed the current scope of capabilities of the different participants. A concentrator module was even included as part of the set. Short-circuit current (Isc), open-circuit voltage (Voc), fill factor (FF), and peak power (Pmax) results are reported

Analysis of the output of two isotype cell sets compared to a precision spectroradiometer

Isotype cells can be used to obtain coarse measurements of the solar spectrum relevant for multi-junction photovoltaic outdoor performance characterization. However, the present literature lacks detailed comparisons between these sensors and high quality spectroradiometer systems. A measurement campaign has been performed over several days where the outputs of two different isotype sensor sets are compared against the output of an OL750 spectroradiometer. The current generation of each isotype cell has been calculated using its measured spectral response and the spectrum measured by the OL750. The current generation ratios between the different junctions are then calculated, and compared with the measured isotype outputs. The results show a consistent relationship between both sets of isotype cells and the spectroradiometer, with a standard deviation between values of less than 1%. These results support the use of isotype sensors for obtaining broadband spectral measurements of the solar spectru

Intercomparison of pulsed solar simulator measurements between the mobile flasher bus and stationary calibration laboratories

The Swiss Mobile Flasher Bus (SMFB) is equipped with a standard high-quality flasher and a very high throughput of up to 200 PV modules per day could be reached direct at customer site. Recently an analysis of the SMFB’s measurement uncertainty budget was presented, resulted in an expanded combined uncertainty of ±3% at a 95% confidence level for standard crystalline Silicon modules. This uncertainty value is about 1% larger than values of the best stationary test labs but enables still very accurate measurements at ambient temperature conditions with the advantage to make more measurements directly on customer’s site. In this paper this uncertainty values were tested by intercomparison of measurement results of the SMFB and the stationary JRC ESTI laboratory on the same PV modules performed within the same hour to reduce uncertainty contributions by instability of the device under test DUT. The largest difference of nominal power measurements was found to be smaller 0.5% for polycrystalline standard modules including the precision measurement at Fraunhofer ISE on the same DUT performed 20 months before. Measurements on standard thin film CIS PV modules resulted in deviations up to 3.7% which are within the calculated SMFB overall uncertainty value of 4%. No light pre-conditioning was performed to the CIS modules and different flasher pulse length was used, 10ms for the SMFB and 1.2ms for the stationary laboratory flasher. In a second intercomparison run the spectral response measurement on module level of SMFB and the JRC ESTI was performed by the use of band pass filters of about 50nm width. The good correlation of the results show that the SMFB spectral response measurement is valuable to calculate the spectral mismatch factor to account for different spectral characteristics of measured PV module, the used monitor cell and the flashers spectra to optimise the overall measurement uncertainty of the SMFB

Indoor-Outdoor Characterisation of Luminescent Solar Concentrators at the European Solar Test Installation

Several 5×5 cm2 LSCs have been characterised, both indoor and outdoor at the European Solar Test Installation laboratories at the Joint Research Centre of the European Commission. Performance on several air-mass conditions has been investigated with device mounted both on tracking and static systems. Results stress the advantages in performance of these devices with regard of diffuse light and in comparison with conventional concentrators, which require complex and expensive tracking systems.JRC.F.8-Renewable Energy (Ispra

Improvement of accuracy and precision of spectral irradiance measurements in annual spectroradiometer intercomparison, 35th EUPVSEC, Sept 2018, Brussels, Belgium

Energy yield measurement and radiation yield determination in the field of photovoltaics (PV) are subject to fast development regarding estimation uncertainties and error in prediction [1]. Both are determined mainly by constraints given by equipment development, calibration schemes and operation routines. Further, an increasing range of PV technologies is available on the market showing rather different spectral responsivities. These require precise PV device calibrations, either outdoor or indoor, with accurate measurement of the light-source. Under these boundary conditions accurate spectrally resolved solar irradiance measurements are gaining higher importance compared to recent years. Finally also PV energy yield estimations (predictions) may benefit from more accurate information on the solar spectrum. The International Spectroradiometer and Broadband intercomparison (ISRC) is evaluating measurement devices, measurement routine and equivalence in measurement results. Last year edition involved 9 scientific institutions and 5 commercial partners of 8 countries, testingmeasurement capabilities and best practices in spectrally resolved solar irradiance between 300 nm and 1700 nm. This work compares results and best practice approaches during the recent years of intercomparison. Capability of precision improvements in measurement as well as deviation in measurement approaches, instruments and institutes are highlighted. The analysis aims to conclude on effects of harmonization efforts, spreading of best-practice measurement routines and discussions on certain aspects such as temperature control or traceability of calibration