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

Abstract

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.

Results of the Fifth International Spectroradiometer Comparison for Improved Solar Spectral Irradiance Measurements and Related Impact on Reference Solar Cell Calibration

“…Due to the technical differences among various instruments in the measurement timing, bandwidth and spectral resolution, specific procedures for data acquisition, synchronization and analysis were developed in order to make the spectroradiometers' output data comparable to each other. Data processing procedures are summarized below and described in more detail elsewhere [3][4]. Prior to the intercomparison, each participating laboratory calibrated their own spectroradiometer(s) following their usual procedures, thus allowing evaluating the instrument performance together with its traceability chain and calibration procedure.…”

“…This constraint limited the useful sky conditions to clear or almost clear and discarded acquisitions at early morning and late afternoon. Moreover, the acquired spectra were also convoluted using a Gaussian function in order to increase and harmonize the spectral bandwidth to 4 nm full width half maximum (FWHM); this is done to reduce artefacts when comparing spectra in the atmospheric absorption bands [3][4]. Several analyses were performed on acquired data, both in terms of absolute spectral irradiance and of spectral shape deviations.…”

Uncertainty analysis of a radiative transfer model using Monte Carlo method within 280–2500 nm region

“…This spectral range contains the regions: ultraviolet-B (UV-B, from 280 nm to 315 nm), ultraviolet-A (UV-A, from 315 nm to 380 nm), visible (VIS, from 380 nm to 780 nm), near infrared (NIR, from 780 nm to 1400 nm) and part of short wave infrared (SWIR, from 1400 nm to 3000 nm). The range is broad enough to include the spectral responsivity of all commercially available photovoltaic modules, usually ranging from 300 nm to 1300 nm (Silverman et al, 2014), and next generation PV technologies currently in the lab stadium, as well as of spectroradiometers (Galleano et al, 2015). An aerosol model, which is then modified according to the aerosol properties provided as input, referred to as aerosol default, and corresponding to the model by Shettle and aerosols (1990): a rural type aerosol in the boundary layer, background aerosol above 2 km, spring-summer conditions and a visibility of 50 km.…”

Results of the IX International Spectroradiometer Intercomparison and impact on precise measurements of new photovoltaic technologies

“…Spectroradiometry has become a key discipline in order to achieve precise measurements in the photovoltaic sector, from top-level calibration laboratories to industry in the production chain 1,2 ; new challenges have to be tackled, considering the increasing importance of an energy rating approach 3 Since 2011, the International Spectroradiometer Interlaboratory Comparison (ISRC) takes place in different locations of Europe with the participation of top level laboratories, research institutes and industrail partners. [4][5][6] At present, the need for a precise measurement of the spectral irradiance is due to the ample and continuously increasing variety of technologies and materials used for cutting-edge PV devices, characterized by very different spectral responsivities with respect to the reference devices used for their calibration. 7,8 This latter can be crystalline Si (with or without optical filters for reducing spectral sensitivity) used for outdoor or in indoor solar simulators or pyrheliometers and cavity radiometers for outdoor calibration.…”