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

Comparison of Spectral Characterization Measurements on Pulsed Solar Simulators and Impact on the Calibration of a Multijunction Thin Film Module

The large variety of photovoltaic (PV) technologies today available on the market makes the characterization of the spectral content of the used light sources a key parameter for calibration and energy yield estimation of PV devices. The use of pulsed, artificial light sources is spread worldwide but these solar simulators have the disadvantage of producing light beams with a spectral content rather different from the Air Mass 1.5 global (AM1.5g) standard spectrum, thus requiring a careful correction of the spectral mismatch between actual and standard spectral conditions. The spectral mismatch correction factor (MMF) may be difficult to apply in the PV module calibration process if reference and calibrating devices have different spectral responsivities and/or if the calibrating device is a multi-junction one. This paper describes the comparison results on the spectral measurements of three pulsed solar simulators performed at two ISO 17025 accredited PV calibration laboratories. Two fast spectroradiometer systems calibrated and traceable to SI units were used for the purpose. Moreover, the impact these results may have on a multi-junction thin film PV module calibration will be analyzed and reported.JRC.F.7-Renewables and Energy Efficienc

Uncertainty propagation of Spectral Matching Ratios measured using a calibrated spectroradiometer

The international standard IEC62670-3 (International Electrotechnical Committee) “Photovoltaic Concentrators (CPV) Performance Testing—Part 3—Performance Measurements and Power Rating” sets the guidelines for power measurements of a CPV device, both in indoor and outdoor conditions. When measuring in outdoor conditions, the acquired data have to be filtered a posteriori, in order to select only those points measured with ambient conditions close to the Concentrator Standard Operating Conditions (CSOC). The most stringent requirement to be met is related to the three Spectral Matching Ratios (SMR), which have all to be within the limit of 1.00 0.03. SMR are usually determined by the ratio of the currents of component cells to monitor the outdoor spectral ratio conditions during the CPV device power measurements. Experience demonstrates that obtaining real world data meeting these strict conditions is very difficult in practice. However, increasing the acceptable range would make the entire filtering process less appropriate from a physical point of view. Given the importance of correctly measuring the SMR, an estimation of their associated measurement uncertainties is needed to allow a proper assessment of the validity of the 3% limit. In this study a Monte Carlo simulation has been used, to allow the estimation of the propagation of uncertainties in expressions having the and integral form. The method consists of applying both random and wavelength correlated errors to the measured spectra and to the measured spectral responses of the three CPV cell junctions, according to the measurement uncertainties of the European Solar Test Installation (ESTI). The experimental data used in this study have been acquired during clear sky conditions in May 2016, at ESTI’s facilities in Ispra, northern Italy (45490 N 8370 E).JRC.C.2-Energy Efficiency and Renewable

New Correction Procedure for IV Curves Measured Under Varying Irradiance

The IEC standard 60891 describes the translation of measured IV curves from the measured irradiance and temperature to the desired irradiance and temperature. The equations given are applicable for IV curves measured at an irradiance which is constant during the IV sweep. In the case of a varying irradiance during the acquisition of the IV curve, as is the case on pulsed solar simulators with a decaying light intensity, the equations have to be modified. This paper illustrates the limitations of the existing standard, proposes a solution for these cases and provides evidence of its proper functioning.JRC.F.8-Renewable Energy (Ispra

DETERMINATION OF INTERNAL SERIES RESISTANCE OF PV DEVICES: REPEATABILITY AND UNCERTAINTY

ABSTRACT: Accuracy and reliability in the determination of series resistance RS of PV devices is an important issue, not only in industrial production environment, because of the parasitic and power consuming nature of this intrinsic parameter, but also in measurement and test laboratories, due to its influence during the translation of measured IV curves to reporting conditions. This work follows standard IEC 60891 ed.2 (2009) for the determination of the internal series resistance and focuses on the repeatability of the result and its uncertainty. The latter is studied in particular considering a possible variation of device temperature during the I-V measurements for the RS determination. An analytical expression is derived for quantifying the additional apparent series resistance ∆RS due to temperature variation. Experimental results confirm the derived expression. Although the standard IEC 60891 ed.2 (2009) states that a constant device temperature is required during the I-V curve measurements, it sets the limits for stability within ±2°C. Here it is found that this would lead to a deviation ∆RS, which is comparable to RS itself. However, if the temperature variation is limited to ±0.1°C, which is achievable on pulsed solar simulators, the deviation of RS is limited to ±5%. The repeatability of RS was found to be typically better than 5%. Conservatively, simply adding the two components, the overall combined expanded uncertainty (k=2) for the determination of RS is found to be ±10%. It is recommended to revise IEC 60891 ed.2 concerning the device temperature during determination of RS.JRC.F.7-Renewables and Energy Efficienc

Uncertainty Propagation of Spectral Matching Ratios Measured Using a Calibrated Spectroradiometer

The international standard IEC62670-3 (International Electrotechnical Committee) “Photovoltaic Concentrators (CPV) Performance Testing—Part 3—Performance Measurements and Power Rating” sets the guidelines for power measurements of a CPV device, both in indoor and outdoor conditions. When measuring in outdoor conditions, the acquired data have to be filtered a posteriori, in order to select only those points measured with ambient conditions close to the Concentrator Standard Operating Conditions (CSOC). The most stringent requirement to be met is related to the three Spectral Matching Ratios (SMR), which have all to be within the limit of 1.00 ± 0.03. SMR are usually determined by the ratio of the currents of component cells to monitor the outdoor spectral ratio conditions during the CPV device power measurements. Experience demonstrates that obtaining real world data meeting these strict conditions is very difficult in practice. However, increasing the acceptable range would make the entire filtering process less appropriate from a physical point of view. Given the importance of correctly measuring the SMR, an estimation of their associated measurement uncertainties is needed to allow a proper assessment of the validity of the 3% limit. In this study a Monte Carlo simulation has been used, to allow the estimation of the propagation of uncertainties in expressions having the and integral form. The method consists of applying both random and wavelength correlated errors to the measured spectra and to the measured spectral responses of the three CPV cell junctions, according to the measurement uncertainties of the European Solar Test Installation (ESTI). The experimental data used in this study have been acquired during clear sky conditions in May 2016, at ESTI’s facilities in Ispra, northern Italy (45°49′ N 8°37′ E)

Analysis of temperature coefficients of bifacial crystalline silicon PV modules

Bifacial c-Si photovoltaic (PV) modules can increase the performance of traditional PV modules because both sides of the cells, front and rear, absorb solar radiation. The knowledge of the temperature coefficients (TCs) is relevant to compare indoor and on-field performance of PV devices. In this paper, the TCs of c-Si bifacial PV modules from five different manufacturers were measured under natural sunlight and simulated indoor condition with a large-area steady-state solar simulator and the data were compared with the datasheet values. The effects on the TCs of an opaque and a reflective rear cover were also analyzed. There were no relevant differences between indoor and outdoor and for front and rear side TCs (within the measurement uncertainty). Slight differences with respect to the datasheet values were found for most of the modules under test for the TC for current α and for maximum power δ coefficients. However, since the manufacturers do not declare the TC uncertainty, a definitive statement cannot be made.JRC.C.2-Energy Efficiency and Renewable

Uncertainty Propagation of Spectral Matching Ratios Measured Using a Calibrated Spectroradiometer

The international standard IEC62670-3 "Photovoltaic Concentrators (CPV) Performance Testing – Part 3 - Performance Measurements and Power Rating" sets the guidelines for power measurement of a CPV device, both under indoor and outdoor conditions. When measuring under outdoor conditions, the acquired data have to be filtered “a posteriori”, in order to select only those points measured with ambient conditions close to the Concentrator Standard Operating Conditions (CSOC). The most stringent requirement to be met is related to the three Spectral Matching Ratios (SMR), which have all to be within the limit of 1.00 ± 0.03. SMR are usually determined by the ratio of the currents of component reference cells set to monitor the outdoor spectral ratio conditions during the CPV device power measurements. Alternatively the SMR can be calculated from measured spectral irradiance if the spectral responsivities of the junctions are known. Experience demonstrates that obtaining real world data meeting these strict conditions is very difficult in practise. However, increasing the acceptable range would make the entire filtering process less appropriate from a physical point of view. Given the importance of correctly measuring the SMR, an estimation of their associated measurement uncertainties is needed to allow a proper assessment of the validity of the 3% limit. In this study a Monte Carlo simulation has been used, to allow a preliminary estimation of the propagation of uncertainties for SMR measured with a calibrated spectroradiometer. The method consists of applying both random and wavelength correlated errors to the measured spectra and to the spectral responses of the three CPV cell junctions, accordingly to the measurement uncertainties of the European Solar Test Installation (ESTI). The experimental data used in this study have been acquired during clear sky conditions in May 2016, at ESTI's facilities in Ispra, northern Italy (45°49′N 8°37′E ). Several considerations are then inferred in the case of SMR measured with component reference cells.JRC.C.2-Energy Efficiency and Renewable