双面光伏组件I-V测试方法研究-曾祥超

1 Study on Bifacial module Current-Voltage characteristics Measurement Zeng Xiangchao, XI’AN, NOV 2018 2 01 02 Outline Current status of testing standards for Bifacial Module Bifacial module I-V test experiment Analysis and Summary 03 04 Two- Side Illumination Solar Simulator 3 Current status of testing standards for Bifacial Module 4 Draft Standards 1. IEC 60904-1-2 Draft Technical Specifications 2. Standards of China Photovoltaic Association 3. SEMI Draft Standard 5661C 4. Others： TUV Rhineland， TUV Nord， CQC… The front 3 are in drafting 1. Current status of testing standards for Bifacial Module IEC 60904-1-2 Equivalent Light Intensity, Two – Side Illumination, Outdoor Test Equivalent Light Intensity : minmaxf maxr scf P P, I IBiFi     scr 1. Current status of testing standards for Bifacial Module Test electrical performance of both sides under STC separately ， and then calculate the electrical performance of Bifacial modules Standards of China Photovoltaic Association Formula Method sc sc rear front IR I )1( RI s cI s c f r o n tB i Fi  B i F i B i F i B i F i B i F iP m a x V o c I s c F F   1. Current status of testing standards for Bifacial Module simultaneously illuminate bifacial solar modules on both sides The front light source is direct-light， rear light source is scattered light SEMI Draft Standard 5661C Two – Side Illumination 1. Current status of testing standards for Bifacial Module Comparison of 3 draft standards Equivalent Light Intensity Formula Method Both – Side Illumination Flash Type Single Flash， Light Intensity ＞1200W/m2 Single Flash Front Illumination + Rear Illumination Rear Light Intensity 100W/m2.200W/m2 100W/m2 100-500W/m2 Bifaciality coefficient No need to test Tests 3 times 2 times 1 time Tested Value Front equivalent light intensity test Simulating both sides performance Real Test Advantage Easy Operation Easy Operation and higher precision Ideal testing solutions, highest precision Dis- advantage principle is controversial and test is inaccurate Simulating accuracy is affected by the rear performance More light source are needed minmaxf maxr scf P P,IIBiFi  scr sc sc rearfront IR I 3 Testing Method, which one is the best？ 1. Current status of testing standards for Bifacial Module 9 2. Bifacial module I-V test experiment 2. Bifacial module I-V test experiment Method 1. Using 6 types of solar modules, and 1 pcs for each type 2. Using one machine, test all the solar modules under same conditions 3. Test modules by using Equivalent Light Intensity, Formula Method and Two-Side Illumination Fundamental Testing Data Module Type SN Module Type Front Side (STC) Rear Side (STC) PmaxBiFi IscBiFi MIN（ PmaxBiFi， IscBiFi） Voc Isc FF Pmax Voc Isc FF Pmax 1 60-mono PERC 39.88 9.657 76.92% 296.3 39.21 6.481 76.48% 194.4 65.6% 67.1% 65.6% 2 72-mono PERC 48.16 9.559 78.15% 359.7 48.13 6.667 78.19% 251.3 69.9% 69.7% 69.7% 3 60-poly PERC 39.45 9.561 75.99% 286.6 38.86 6.727 78.55% 205.3 71.6% 70.4% 70.4% 4 60 N type half-cell 39.60 9.944 78.74% 310.1 39.38 8.252 78.91% 256.4 82.7% 83.0% 82.7% 5 60 N type full cell 38.98 9.626 78.36% 294.0 38.65 8.219 79.67% 253.0 86.1% 85.4% 85.4% 6 60 HIT 43.26 9.106 74.45% 293.3 43.07 8.424 74.74% 271.1 92.4% 92.5% 92.4% Remark： Voc Unit V， Isc Unit A， Pmax Unit W. 2. Bifacial module I-V test experiment The Pmax difference between the highest value of the equivalent light intensity method and the formula method and the double-sided glazing method at 200 W/m 2 2. Bifacial module I-V test experiment Equivalent Light Intensity Formula Method-Equivalent Mono PERC (60 Cells) Mono PERC (72 Cells) Poly PERC (60 Cells) N Type (60 Cells, ½ cell) HIT (60 Cells) N Type (60 full cell) -2.7 -1.0 -1.6 -4.6 -6.7 -1.9 -0.4 0.2 0.4 -2.9 -6.3 3.0 -8.0 -6.0 -4.0 -2.0 0.0 2.0 4.0 Pmax value under 200W/m2 Isc difference under 200W/m2 Light Intensity 2. Bifacial module I-V test experiment -0.093 -0.002 -0.056 0.000 -0.223 0.012 -0.086 -0.007 -0.030 -0.028 -0.215 -0.010 -0.250 -0.200 -0.150 -0.100 -0.050 0.000 0.050 Equivalent Light Intensity Formula Method-Equivalent Mono PERC (60 Cells) Mono PERC (72 Cells) Poly PERC (60 Cells) N Type (60 Cells, ½ cell) HIT (60 Cells) N Type (60 full cell) The Isc difference between the highest value of the equivalent light intensity method and the formula method and the double-sided glazing method at 200 W/m 2 FF is the highest by using Front STC 2. Bifacial PV module I-V test experiment FF Difference by 3 methods 200W/ m2 Light Intensity Two –Side Illumination Equivalent intensity Front STC Data Analysis 1. By using different methods, the Pmax value is different. Under 200W/m2 rear light intensity, Max power difference is even 6.7W（ 1.9%） by using Two- Side Illumination and Equivalent Light Intensity. 2. Under 200W/m2 rear light intensity, Max Isc difference is 0.223A（ 2%） by using Two- Side Illumination and Equivalent Light Intensity. Conclusions： The electrical performance parameters obtained by the three test methods are inconsistent and not regular 2. Bifacial PV module I-V test experiment 16 3. Analysis and Summary 17 3. Analysis 01  As the Bifacial Coefficient obtained by the equivalent Light Intensity is the Minimum of (PmaxBiFi, IscBiFi), and that selected by the Formula Method is IscBiFi. Two values of different modules are not totally same.  Series Loss Effect FF tested by Equivalent Light Intensity and Two-Side Illumination is lower than Front STC method 18 02 If there is serious inconsistency or shield rear , Isc may not be affected, but Pmax values definitely is affected Rear STC Test Two Side Illumination 3. Analysis Step Two- Side Illumination Rear side Illumination 19 03 With the light intensity increase, the series resistance decreases in a non-linear way, and the series loss increases in a non-linear way, leading to the reduction of the filling factor FF 0 0.2 0.4 0.6 0.8 1 1.2 1.4 200 300 400 500 600 700 800 900 100011001200 Rs vary with Light Intensity 0.78 0.785 0.79 0.795 0.8 0.805 0.81 0.815 0.82 200 300 400 500 600 700 800 900 100011001200 FF vary with light intensity 0 2 4 6 8 10 200 300 400 500 600 700 800 900 1000 Isc vary with light intensity 40 40.5 41 41.5 42 42.5 43 43.5 200 300 400 500 600 700 800 900 1000 Voc vary with Light Intensity 3. Analysis 20 04 As different cell has different weak light response and series resistance, the Pmax of different solar modules do not increase linearly with light intensity (the light intensity below is normalized to 1000W ), Equivalent Light Intensity method is biased 290 292 294 296 298 300 302 200 300 400 500 600 700 800 900 1000 HIT Pmax 280 282 284 286 288 290 292 294 200 300 400 500 600 700 800 900 1000 1100 1200 Poly PERC Pmax 280 282 284 286 288 290 292 294 200 300 400 500 600 700 800 900 1000 1100 1200 Mono PERC Pmax 298 300 302 304 306 308 310 312 314 316 200 300 400 500 600 700 800 900 1000 1100 1200 N Type Pmax 3. Analysis 21 1. Test 6 types solar modules by using 3 methods respectively , different methods obtain different testing results. 2. Rs, Rsh ,FF, Eff and etc of solar modules change Nonlinear with changes in light intensity, which has a great impact. 3. On the electrical performance of solar modules, the test could not be done simply by increasing light intensity. 3. Summary 22 3. Summary How to Measure Bifacial Module ? 23 The final performance of bifacial module in a power plant depends on the spatial distribution of the irradiance incident on the rear surface of the device, which is strongly affected by site-specific conditions, both direct and reflective light illuminates on solar modules, Different installation surface has different reflective light intensity 3. Summary 24 Indoor test should simulate actual application condition, Two-side illumination is the best and highest precision testing solution 3. Summary 25 4. Two- Side Illumination Solar Simulator Index Front Light Source Rear Light Source Pulse Duration（ ms） 10～ 100 10～ 150 Light Intensity （ W/m2） 700～ 1200 100～ 500 Class A+A+A+ AAA Light Distance （ mm） 3000 900 Light Type Direct - Light Diffuse – reflective light Solar Simulator 4.1 Two – Side Illumination Solar Simulator Dark Room Solar Module Shading Material  Testing Conditions 4.1 Two – Side Illumination Solar Simulator IV Curves Both Side Illumination simultaneously Front Illumination Rear Illumination 4.1 Two – Side Illumination Solar Simulator The current tends to stabilize before the voltage changes Current does not reach steady state The high-capacity battery is tested with a 10ms linear voltage sweep. As the bias voltage rises, the internal capacitance of the battery increases. After each voltage adjustment, the time required for the current to stabilize increases. 4.2 Capacitance effect Early Experiment Capacitance Effects Sweep Time is not enough 4.2 Capacitance effect