Field testing of portable led flasher for nominal power measurements of pv-modules on-site

Nominal power measurements of individual PV modules are needed to quantify the critical modules of PV plants offering lower energy production than expected. Today’s state of the art procedure of shipping a small number of modules to a laboratory is time- and cost intensive and it bears the chance of accidental damage. The Portable LED Flasher (PLF) was developed to require no dismounting of the modules. The quality of the PLF was tested on three PV plants in Switzerland. Additionally, ten PV modules of each plant were measured in the certified indoor laboratory of SUPSI, resulting in a maximum deviation of 3% of the STC values. Furthermore, a round robin test on a single crystalline silicon reference module at 25°C was performed at the JRC’s ESTI laboratory, the Swiss Mobile Flasher Bus and SUPSI resulting in a maximum deviation of the mean values below 1% compared to the PLF. A throughput of up to 150 modules or 500 modules respectively per day is expected and the total measurement costs are estimated to be about a tenth of the costs compared to an indoor laboratory. Module temperature measurement is crucial for a low total uncertainty. Thus, methods such as pre-shadowing of the module and approximation of cell temperature are the current focus of further improvement of the PLF measurement method

State-of-the-art for assessment of solar energy technologies 2019

To realize the EU target of energy transition to a carbon neutral energy system, wide scale deployment of photovoltaic solar energy is required. This report describes the contribution of the European Solar Test Installation to enable this transition.JRC.C.2-Energy Efficiency and Renewable

State-of-the-art for assessment of solar energy technologies

Photovoltaics (PV) are expected to make a major contribution to achieving European and global climate change mitigation goals over the coming 35 years. It is the renewable energy technology with the largest scope for cost reduction and efficiency gains, as well as exploiting the largest resource. The rapid technical evolution needs to be matched by standards to ensure the highest level possible of product quality, reliability and sustainability, as well as transparent market conditions. This requires reliable, reproducible and widely applicable measurement protocols for the assessment of electrical performance of PV devices of traditional as well as emerging PV technologies. The Joint Research Centre (JRC) plays a prominent role in developing, validating and implementing such measurement protocols, exploiting more than 35 years of expertise developed in the European Solar Test Installation (ESTI), the European Commission’s reference laboratory to validate electrical performance and lifetime of PV devices. The JRC works together with policy makers, industry and the research community to monitor the progress of PV technology and helps develop the solutions for the future. This directly supports the European Union’s objective of attaining an increasing share of renewable energies in the market (20% in 2020 and at least 32% in 2030). ESTI is an ISO/IEC 17025 accredited calibration laboratory. As such, it is involved in benchmarking, intercomparisons (bilateral and round robin (RR)) and proficiency tests to maintain and improve its measurement capabilities for solar irradiance and electrical performance of PV devices. The results of these international activities is directly used, mainly through the International Electrotechnical Commission’s Technical Committee 82 (IEC TC 82), as input for revision of existing standards or for development of new standards for assessment of the electrical performance of PV devices. This work concerns both measurement methods and PV technologies. Furthermore, ESTI actively promotes transfer of knowledge about the measurement procedures to the European and International research community, provides the PV traceability chain by generating PV reference materials for its partners and clients and offers verification of PV devices (mainly based on new technologies). In this report the activities of 2018 are summarised. Starting from the traceability chain of solar irradiance measurements according to international standards, the activities of ESTI in establishing the PV traceability chain at its own laboratory is outlined. Then the activities in international intercomparison measurements for the major instruments used in the traceability chain are described, starting from cavity radiometers and spectroradiometers to PV devices (both cells and modules). These serve to establish the traceability, stability and conformity of ESTI calibration measurements. This in-house metrology activity is then used to provide the PV traceability chain to clients and partners by generating reference materials, i.e. by calibrating PV cells and modules for them under the ISO/IEC 17025 accreditation as calibration laboratory. Another crucial activity is to verify those PV devices which claim to have achieved extraordinary performance, be it world record efficiencies or other performance beyond the usual. Last not least, the activities on measurement methods are described, which span from the actual development of new methods and their validation to their implementation into the ESTI quality system and ISO/IEC 17025 accreditation scope. Thereby, this annual report: — verifies the status of ESTI’s unique independent traceability chain for solar irradiance measurements; — summarises benchmarking activities with peer external international organisations; — summarises results of PV device calibrations performed for EU industry and research organisations; — provides an update on the adequacy of measurement methods used to assess the electrical performance of PV products and prototypes.JRC.C.2-Energy Efficiency and Renewable

Analysis and Mitigation of Measurement Uncertainties in the Traceability Chain for Calibration of Photovoltaic Devices

This paper describes the traceability chain for photovoltaic devices and the measurement methods employed to perform the various transfer steps. The measurement uncertainties are analysed in detail based on the accreditation of the European Solar Test Installation (ESTI) for calibration of photovoltaic devices. The various contributions to the overall uncertainty are critically analysed for various traceability chain options. A major contribution is the uncertainty in the calibration of the primary reference device. The overall measurement uncertainty is reduced using ESTI reference cell set compared to the traceability from the world photovoltaic scale (WPVS). For the maximum power of photovoltaic modules, the expanded combined uncertainty is reduced from ±2.6% to below ±2%. Recommendations are made on the scope for further reduction of uncertainty and for the best calibration strategy for various PV technologies.JRC.F.8-Renewable Energy (Ispra

High spatial resolution system for measuring solar and circumsolar radiation

Concentrating photovoltaic systems (CPVs) are sensitive to a correct alignment with current sun position because of the optical principle at the basis of their operation; indeed, the higher the concentration factor, the more sensitive they are. Therefore, solar trackers and high-quality focusing optics are used to maximize the cells’ exposure to sun disk’s radiation. This increases costs, so that viability of CPV systems strongly depends on the location and on high quality information or model of the irradiance conditions. For this purpose, pyrheliometers (or, sometimes, collimated isotype cells) are used to acquire on-site data for direct normal irradiance, but they are not perfectly suitable for CPVs because they have a wider field of view (5°) and so they overestimate the actual irradiance seen by the concentrating system. As an alternative, a collimated sun-scanning setup with an aperture angle of 0.13° has been developed for measuring the solar and the circumsolar radiation distributions with high spatial resolution. In fact it has an angular positioning accuracy of ±0.002° and an angular pointing precision of ±0.007°. It is also intended to provide a simple but effective tool for building up a consistent database of local sunshapes.JRC.F.7-Renewable Energ

Analysis and Mitigation of Measurement Uncertainties in the Traceability Chain for Calibration of Photovoltaic Devices

This paper describes the traceability chain for photovoltaic devices and the measurement methods employed to perform the various transfer steps. The measurement uncertainties are analysed in detail based on the accreditation of the European Solar Test Installation (ESTI) for calibration of photovoltaic devices. The various contributions to the overall uncertainty are critically analysed for various traceability chain options. A major contribution is the uncertainty in the calibration of the primary reference device. The overall measurement uncertainty is reduced using ESTI reference cell set compared to the traceability from the world photovoltaic scale (WPVS). For the maximum power of photovoltaic modules, the expanded combined uncertainty is reduced from ±2.6% to below ±2%. Recommendations are made on the scope for further reduction of uncertainty and for the best calibration strategy for various PV technologies.JRC.F.8-Renewable Energy (Ispra

Polycrystalline silicon PV modules performance and degradation over 20 years

The presented paper reports the results of the experimental work performed at European Solar Test Installation (ESTI), using an array of 70 polycrystalline silicon photovoltaic (PV) modules by the same manufacturer. After almost 20 years of continuous outdoor exposure, the modules were subjected to a comprehensive indoor test plan; in particular, electrical performance measurements were performed, together with a detailed visual analysis. It was also possible to perform a comparison between final and initial data (in particular IV characteristics): module average performance decay is 4,42% for the whole period. Degradation mechanisms, together with their effect on module lifetime, were also analyzed. Results of such a measurement exercise clearly show how photovoltaic device reliability over decades can guarantee safe investments, for the benefit of all PV users and stakeholders. The authors are currently installing the modules for further 20 years of outdoor exposure.JRC.F.7-Renewable Energ

Traceable calibration of photovoltaic reference cells using natural sunlight

To calibrate the electrical performance of photovoltaic (PV) modules, the incident irradiance of the natural or simulated sunlight is measured by PV reference cells. This measurement is the most difficult part concerning traceability and contributes significantly to overall measurement uncertainty. At the European Solar Test Installation (ESTI) PV reference cells are calibrated traceably to the World Radiometric Reference (WRR) using natural sunlight. These calibrations are shown to be fully consistent with other methods directly traceable to SI units. Based on the combined calibration results for a set of PV reference cells, the World PV Scale (WPVS) is established. This provides a useful means for routine calibration of other PV devices.JRC.C.2-Energy Efficiency and Renewable

Performance of Thin Film PV Modules

Estimation of the electrical yield of a PV module is expected to be a more useful predictor of performance for installers than Wp alone. A method for the Energy Rating of PV modules based on performance surfaces under development at the ESTI laboratory uses the module temperature and incident irradiance as independent variables and has been successful in prediction of real energy production for crystalline Si modules. However, it was found to be more difficult to accurately predict the performance of thin film modules, and it was therefore necessary to explore the reasons. One potentially significant parameter not included in the standard performance surface is the effect of spectral variations and this has been studied during indoor and outdoor testing on CIS and a-Si modules. The outdoor measurements were performed on a tracker so as to preclude angle of incidence effects. Module I-V curves and the solar spectrum were measured at frequent intervals over a range of air mass values during the course of a number of days. A crystalline Si reference device and a pyranometer were used as irradiance sensors in order to explore the effect of the choice of reference device used. The spectral mismatch factor is calculated from measurements of the solar spectrum and device spectral responses and is applied to correct the individual module measurement points. The dependence on air mass i.e. the details of the solar spectrum of these devices has also been shown, so employing only total irradiance and device temperature may not be sufficient when an energy rating is being made. This effect is most pronounced for the a-Si module tested, for which a significant part of this dependence was corrected by the application of the relevant mismatch factors.JRC.H.8-Renewable energie