FRAUNHOFER INSTITUTE FOR SOLAR ENERGY SYSTEMS ISE

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1 FRAUNHOFER INSTITUTE FOR SOLAR ENERGY SYSTEMS ISE The impact of half cells on module power and costs Max Mittag Fraunhofer Institute for Solar Energy Systems ISE Webinar PV-magazine Freiburg,

power Power cells > power module cell-to-module loss (CTM)

2 Cell-to-Module Analysis Motivation Power loss = financial loss ( /Wp) Module materials (BoM) and module design influence power Power cells > power module cell-to-module loss (CTM) Analysis of losses allows techno-economic optimization of PV modules 2

Cell-to-Module Analysis Motivation CTM-optimization increases revenue Solar cells are bought at /Wp PV modules are sold at /Wp Goal: Increase module power without

3 Cell-to-Module Analysis Motivation CTM-optimization increases revenue Solar cells are bought at /Wp PV modules are sold at /Wp Goal: Increase module power without using solar cells with higher power Are half cell modules a promising approach? PV-Module with 5.6% cell-to-module gain, manufactured at Fraunhofer ISE Module-TEC (2016) 3

Mismatch Scientific models allow analysis and prediction Optical gains and losses in PV modules 4

4 Cell-to-Module Analysis Gain and Loss Factors Geometry: inactive areas near the frame and cell spacing Optics: reflection, absorption, transmission, internal shading, light management Electrics: Resistances, Mismatch Scientific models allow analysis and prediction Optical gains and losses in PV modules 4 Haedrich, I. et al, Unified methodology for determining CTM ratios: Systematic prediction of module power, SiliconPV, 2014

5 Cell-to-Module Analysis SmartCalc.CTM free demo-version CTM Geometrie Optik Elektrik Graphical User Interface of SmartCalc.CTM 5 M. Mittag et al., Systematic PV module optimization with the cell-to-module (CTM) analysis software, Photovoltaics International, no. 36

6 Module Design for Half and Full Cell Modules Necessary adaptions for modules with half cells Cell spacing Number of cells Module size full cell half cell Full and half cell module with identical size and cell spacing but with different active area Cell spacing Backsheet reflection gains, electrical losses Number of solar cells Module power, costs Module size costs front glass encapsulant solar cell backsheet Mechanism of backsheet reflection, gains depending on cell spacing 6 M. Mittag et al., Analysis of Backsheet and Rear Cover Coupling Gains for Bifacial Solar Cells, 33 rd EU PVSEC, 2017

7 Cell-to-Module Analysis Half and Full Cells SmartCalc.CTM free demo-version Assumptions necessary to compare concepts, modules and materials Module design for comparative CTM-Analysis Same module size Identical active area Different cell distances Chosen designs are exemplary Full cell Half cell Same module area, same active area, different cell spacing 7

8 Cell-to-Module Analysis Input parameters Full Cell Half Cell Solar cells Length [mm] Width [mm] Cell distance [mm] String distance [mm] Module area [m²] Active area share 87.9% 87.9% Solar cells and other materials are identical in both modules 8

9 Cell-to-Module Analysis Full Cell Module SmartCalc.CTM free demo-version!! 9

Cell-to-Module Analysis Concept Comparison SmartCalc.CTM www.cell-to-module.com Full cell module Full Cell Half Cell Power [Wp] 305 313 CTM power [%] 98.1 100.

10 Cell-to-Module Analysis Concept Comparison SmartCalc.CTM Full cell module Full Cell Half Cell Power [Wp] CTM power [%] Efficiency [%] Reduced electrical losses Larger number of cell spacings Half cell module +0.4 Wp +7 Wp Reduced cell distances Only minor additional gains from internal reflection 10

11 Cell-to-Module Analysis Concept Comparison Full Cell Half Cell Power [Wp] Wp CTM power [%] % abs Efficiency [%] % abs Initial cell power identical in both modules Higher module power with half cells through improved CTM Module area unchanged ( identical BoM) Results change for other module designs detailed analysis necessary Economical analysis possible after calculating the module power 11

12 Techno-Economic Analysis CTM-analysis shows advantages of half cells regarding module power Exact module setup necessary to quantify advantages Module power Cost Calculation Material costs Processes Cost of Ownership Wp 12 J. Shahid et al., A Multidimensional Optimization Approach To Improve Module Efficiency, Power And Costs, 35 th EU PVSEC, 2018

13 Cost of Ownership Analysis Scenario A: Low Additional Costs for Half Cells No additional Stringer No increased cell breakage No extra costs for cell handling No power losses through cell splitting No change in BoM (same module size) Increased power for half cell module (+8 Wp) Additional cell splitting machine Max pcs/h, 300 k Invest Glass EVA Solar cells Ribbons Backsheet Junction Box Frame 4 /m² 0.9 /m² 12 ct/wp 3.5 ct/m 2 /m 3 /pcs 1.10 /m Material Cost Assumptions for the Cost of Ownership (CoO) Calculation 13

14 Cost of Ownership Analysis Scenario A: Low Additional Costs for Half Cells Full cell module 75.8 /Module 25.0 ct/wp Half cell module 76.3 /Module 24.4 ct/wp Results Scenario A: Half cell module with higher absolute costs CTM-power gains reduce specific costs ( /Wp) for half cell modules 14 Example production, only manufacturing costs

15 Cost of Ownership Analysis Scenario B: Additional Costs for Half Cells Additional Stringer: +1 Increased breakage rates: 0.1% (+100% breakage at cell splitting) Additional costs for cell handling: +1% on total invest Power loss through cell splitting: -1% No change in BoM (same module size) Increased power for half cell module (+8 Wp) Additional cell splitting machine Max pcs/h, 300 k Invest Glass EVA Solar cells Ribbons Backsheet Junction Box Frame 4 /m² 0.9 /m² 12 ct/wp 3.5 ct/m 2 /m 3 /pcs 1.10 /m Material Cost Assumptions for the Cost of Ownership (CoO) Calculation 15

16 Cost of Ownership Analysis Scenario B: Additional Costs for Half Cells Full cell module 75.8 /Modul 25.0 ct/wp Half cell module 77.3 /Modul 25.0 ct/wp Results Scenario B: 16 Additional costs through processes and technological risks may compensate power gains Detailed analysis necessary Consideration of additional aspects (System + LCoE) Example production, only manufacturing costs

17 Summary Half cells increase module power (~ 2-3%) Full cell modules with lower absolute costs ( ) Advantage ( /Wp) of half cell modules depends on Manufacturing equipment and processes Impact of cell splitting on breakage rates and power losses Results of techno-economic analysis depend on specific inputs (production environment, module design) Change of module design and topology necessary for half cells (serial and parallel connection of strings) Change of BoM may be necessary (change in module size) 17

Compatibility to future trends Half cells compatible to most new approaches in module design Glass-glass, round wire interconnection, Larger solar cells (156 161 mm) Larger currents and

18 Compatibility to future trends Half cells compatible to most new approaches in module design Glass-glass, round wire interconnection, Larger solar cells ( mm) Larger currents and electrical losses (~ +10%) BoM change likely (module size) Bifaciality Larger currents and electrical losses (up to +30% depending on albedo) Detailed analysis of every setup necessary 18

19 Thank you for your attention! Fraunhofer Institute for Solar Energy Systems ISE

20 Preview SmartCalc.CTM SmartCalc.CTM features in development (coming soon) Non-STC modelling Inhomogeneous module operation Bifaciality Free access to software updates for SmartCalc.CTM users 20 A. Pfreundt et al., Rapid Calculation Of The Backsheet Couping Gain Using Ray Groups J. Shahid et al., A Multidimensional Optimization Approach To Improve Module Efficiency, Power And Costs M. Mittag et al. Approach for a Holistic Optimization from Wafer to PV System

21 Non-STC Modelling SmartCalc.CTM Current increases with irradiance Electrical losses in full cell module especially high for high irradiance (STC) P loss, interconnection ~ I² x R Relative disadvantage of full cell module decreases for low irradiances STC measurements and STC-modelling may overestimate half-cell gains Non-STC modelling and extended characterization necessary for concept evaluation advantage of half cells is smaller at low irradiances (but still there) Non-STC modelling results created with SmartCalc.CTM 21

Presented at the 32nd European PV Solar Energy Conference an Exhibition, June 2016, Munich, Germany

Presented at the 32nd European PV Solar Energy Conference an Exhibition, June 2016, Munich, Germany Towards a 3 W P p-type -Module Simulation, Experimental Results and Costs A. Spribille 1, T. Savisalo 2, A. Kraft 1, D. Eberlein 1, M. Ebert 1, T. Fellmeth 1, S. Nold 1, H. Pantsar 2, F. Clement 1 1 Fraunhofer