EUROPEAN COMMISSION SEVENTH FRAMEWORK PROGRAMME THEME ENERGY-NMP (Joint Call) ENERGY NMP

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1 EUROPEAN COMMISSION SEVENTH FRAMEWORK PROGRAMME THEME ENERGY-NMP (Joint Call) ENERGY NMP GA No Accelerated development and prototyping of nano-technologybased high-efficiency thin-film silicon solar modules Deliverable No. FAST TRACK D6.1 Deliverable Title Dissemination level Report on the requirements for the standardization of module testing Written By Jörg Stanzel (IVX), Paul Sommeling (ECN), Wim Soppe (ECN), Marko Topic (UL) Checked by Jörg Stanzel (IVX) Approved by Aad Gordijn (Jülich) Issue date

2 Publishable summary Well established module characterization procedures are of utmost importance for the assessment of new concepts for silicon based thin film photovoltaic modules. Within the framework of the Fast Track project work package 6 is dedicated to the development of common standards for the characterization of photovoltaic modules that are to be manufactured in the scope of work package 5. Moreover, the work package aims at providing the availability of the necessary testing facilities at different partner sites. In the following report, requirements for successful module testing of prototype modules are defined. The factors that lead to deviations of measurement results at different testing facilities are identified. The hitherto gained experiences from the module round robin test have been taken into account. 2/11

3 Contents 1 Executive summary Introduction Experience from Round Robin test conducted so far Requirements for standardized module testing Parameters to be determined Calibration of Flasher Module related requirements Further requirements Risk Register Conclusion Acknowledgment /11

4 1 Executive summary Work package 6 is dedicated to the development of common standards for the characterization of photovoltaic modules that are to be manufactured in the scope of work package 5. Moreover, the work package aims at providing the availability of testing facilities with common standards at different partner sites. In this report, the requirements for successful module testing are discussed. Experiences from the initial module round robin are taken into account to formulate requirements for a measurement procedure. The following requirements related to the scope of measurements, i.e. the parameters, to be determined during module testing, are proposed: I/V curve at standard testing conditions according to IEC 61646:2008 (1000 W/m², 25 C, spectral distribution according to IEC ) including the maximum power (P mpp ), short circuit current (I SC ), open circuit voltage, fill factor (FF), series resistance (R s ), and parallel resistance (R p ). I/V curve at low irradiance conditions (200 W/m², 25 C, spectral distribution according to IEC ), including Pmpp, Uoc, Isc, FF, Rp, Rs Temperature coefficients for Isc, Uoc, and Pmpp (,,), determined using mini modules Light induced degradation according to IEC 61646:2008, determined using mini modules Spectral response characteristics, determined using mini modules Requirements for the calibration procedure: Manufacturing of so called gold modules; i.e. modules with known performance parameters that are used for calibration of the respective flasher at each testing facility. These modules will be made available on each testing facility, to allow for calibration of the measurement equipment. Standards for storage and light soaking of the gold modules need to be defined Further details on the procedure: Light induced degradation and temperature coefficients of the modules that are to be tested can be determined using so called mini modules on small scale Standards for the proper selection of mini modules from full size modules need to be developed With the establishment of such standards that are to be discussed in details, the performance parameters of prototype modules can be determined at the different testing facilities. We expect a measurement uncertainty of less than 5%. 4/11

5 2 Introduction In the following report the requirements for successful module testing of prototype modules are discussed. The factors that lead to deviations of measurement results at different testing facilities are identified. Based on the experience gathered during the first module round robin, requirements are formulated, that enable the different measurement sites to obtain results that are in agreement within a certain measurement error. 5/11

6 3 Experience from Round Robin test conducted so far A round robin has been started with standard modules by Inventux, Hyet and 3SUN. Characterization was done at Inventux, ECN and the respective module manufacturers. The hitherto gained results of the round robin are shown in the 12M report. The following conclusions are drawn Minimum standards for electrical wiring are needed (especially for outdoor tests) Module size needs to be taken into account, as deviations can occur, when the size of the illuminated area of the respective flasher differs significantly from the size of the module to be measured Low irradiance measurements should be done by applying the standard lamp intensity of 1000 W/m² in combination with attenuating grey filters Temperature coefficients need to be determined in order to account for different measurement temperatures (differing from 25 C) Spectral mismatch factor need to be taken into account Light induced degradation must be determined 6/11

7 4 Requirements for standardized module testing Based on the experience gathered during the module round robin, the following requirements are proposed. 4.1 Parameters to be determined For module characterization purposes the following parameters must be determined: I/V curve at standard testing conditions according to IEC 61646:2008 (1000 W/m², 25 C, spectral distribution according to IEC ) including the maximum power (P mpp ), short circuit current (I SC ), open circuit voltage, fill factor (FF), series resistance (R s ), and parallel resistance (R p ). I/V curve at low irradiance conditions (200 W/m², 25 C, spectral distribution according to IEC ), including Pmpp, Uoc, Isc, FF, Rp, Rs Temperature coefficients for Isc, Uoc, and Pmpp (,, ) Coefficients of light induced degradation for Pmpp, Uoc, Isc, FF, Rp, Rs Spectral response characteristics We explicitly mention performance parameters like temperature coefficients and low irradiance performance, as these parameters play a crucial role for the annual energy yield in terms of kwh produced electricity per kwp installed module power. 4.2 Calibration of Flasher A critical point for the characterization of a Si/µc Si tandem devices is its spectral response characteristic and the spectral mismatch of the light source of the flasher. Consistent results can be achieved by 1. Manufacturing of so called gold modules, i.e. modules with known performance parameters that are used for calibration of the respective flasher at each testing facility. The parameters of the gold modules (see parameters list 4.1) are characterized in the scope of a module round robin at different testing facilities. Two gold modules are stored at each testing facility for flasher calibration purposes. The following issues need to be considered o A procedure for stabilization of gold modules is necessary o Defined storage conditions for gold modules at respective testing facility, An alternative reference for calibration purposes could be a (stable) crystalline silicon cell or module equipped with an appropriate filter to get its QE close to that of the test module. o Known Quantum Efficiency (QE) curve for the gold modules and for the modules to be tested (QE measurement of gold modules by external institutes?) QE curves of gold reference and test module should be very close matching 2. Determination of spectral mismatch factor of each flasher for top and bottom cell limited modules using a crystalline and amorphous reference cell flasher spectrum is required for this, as well as QE for test module and reference module o QE curve determined on mini module level (mini modules are small sample modules with the dimensions 100x100 mm) 3. An alternative reference for calibration purposes could be a (stable) crystalline silicon cell or module equipped with an appropriate filter to get its QE close to that of the test module. After discussing the different options, the partners finally agreed to choose the first method, i.e. manufacturing of gold modules, for the calibration of the flashers. 7/11

8 4.3 Module related requirements Minimum standards for connector to allow for better reproducibility of measurement Standards for stabilizing modules outdoor. Determination of light induced degradation outdoor and comparison with results on mini modules The use of mini modules with the same production process to determine o Coefficients of light induced degradation o Temperature coefficients o Quantum efficiency curve 4.4 Further requirements In cases, where the area of the test module is much smaller than the illuminated area of the flasher, measurement uncertainty due to spatial in homogeneity of the flasher can be taking into account by performing measurements at different positions inside the flasher. 8/11

9 5 Risk Register Risk No. What is the risk Level of Solutions to overcome the risk risk 1 WP6.1 The Determination of temperature coefficients and light induced degradation on mini module level might be insufficient due to in homogeneity issues 2 Mini modules from different positions on the substrates are used. Cross check with outdoor results on fullsize modules WP6.2 Degradation effects on gold modules during storage. This might affect Flasher calibration. 2 Standard production recipes are used with proven stability. 1 Risk level: 1 = high risk, 2 = medium risk, 3 = Low risk 9/11

10 6 Conclusion Based on the work conducted during work package 6, requirements are proposed for successful module characterization of prototype modules on different testing facilities. With the proposed measures taken into account, we expect a measurement uncertainty of 5% for Pmpp, Uoc, and Isc, and light induced degradation, a measurement uncertainty of ± 10 % for determination of temperature coefficients and relative low irradiance efficiency. 10/11

11 7 Acknowledgment This project is co funded by the 7th FP (Seventh Framework Programme) of the EC European Commission DG Research Disclaimer The FP7 project has been made possible by a financial contribution by the European Commission under Framework Programme 7. The ation as provided reflects only the authors view. Every effort has been made to ensure complete and accurate information concerning this document. However, the author(s) and members of the consortium cannot be held legally responsible for any mistake in printing or faulty instructions. The authors and consortium members retrieve the right not to be responsible for the topicality, correctness, completeness or quality of the information provided. Liability claims regarding damage caused by the use of any information provided, including any kind of information that is incomplete or incorrect, will therefore be rejected. The information contained on this website is based on author s experience and on information received from the project partners. 11/11