Environmental Stresses and Field Analysis of Materials for Distributed PV Applications

Transcription

1 D u P o n t P h o t o v o l t a i c S o l u t i o n s May 29 th, 2018 Environmental Stresses and Field Analysis of Materials for Distributed PV Applications SNEC 2018 Scientific Conference Hongjie Hu, Kaushik Roy Choudhury, William Gambogi, Summer Xia, Oakland Fu, T. John Trout, and Ethan. S. Simon 2018 DowDuPont. All rights reserved.

2 China PV Installations Increased Rapidly in Last 3yrs, Distributed PV (DPV) Had Booming Growth China PV Installations (GW) New Installation DPV Expon. (DPV) Data source: CPIA 2018 DowDuPont. All rights reserved. D u P o n t P h o t o v o l t a i c S o l u t i o n s 2

3 DuPont Collaborates with Downstream Stakeholders to Assess PV Systems, Modules, and Materials in the Service Environment Inspected ~400 solar installations in NA, EU and AP by 2018 Including > 1GW & 4.2 million solar panels Age of 0-30+yrs 2018 DowDuPont. All rights reserved. D u P o n t P h o t o v o l t a i c S o l u t i o n s 3

4 DuPont 2018 Field Analysis and Database - Overview 2018 Analysis 1+ GW inspected Climate sample sizes 2018 Statistical Analysis and Case Studies Data size more than doubled from 2016 to 1+ GW All defects 22.3% Cell related defects 12% Backsheet defects 9.5% kw inspected D u P o n t P h o t o v o l t a i c S o l u t i o n s Internal Use Only 4

5 Defect Rates for Roof vs. Ground Mounted Systems Total Roof mounted 19 MW Overall Higher defect rates for roof vs ground installations Backsheet defects are > 2.5X higher on roof systems Cell defects are similar for Roof and Ground Ground mounted 1028 MW Differences are likely due to higher temperatures for roof systems Roof Systems are typically 15 C higher than Ground Mounted 1 This trend with temperature is similar to the effect seen in climates 1 Creep in Photovoltaic Modules: Examining the Stability of Polymeric Materials and Components (2010) 35th IEEE Photovoltaic Specialists Conference (PVSC 10) Honolulu, David C. Miller, Michael Kempe 2018 DowDuPont. All rights reserved. D u P o n t P h o t o v o l t a i c S o l u t i o n s 5

6 Analysis of Defect Rate vs. Backsheet Materials Backsheet defects increased by 27% vs 2016 Analysis Polyamide increased by 18% PVDF increased by 51% Glass / Glass starting to show up Tedlar rate unchanged 2018 DowDuPont. All rights reserved. D u P o n t P h o t o v o l t a i c S o l u t i o n s 6

7 Tedlar PVF-based backsheets in the field: Low power loss and no degradation SUPSI Switzerland % annual power loss Nara, Japan, % annual power loss SMUD USA % annual power loss SYSU China % annual power loss Mont Soleil, Switz % annual power loss Beijing % annual power loss 2018 DowDuPont. All rights reserved. D u P o n t P h o t o v o l t a i c S o l u t i o n s 7

8 General Requirements for Rooftop PV Systems Durability Aesthetics Fire Safety High Temp. High Efficiency Greater Temp. Range Light Weight & Easy Installation High UV albedo for open rack installation 2018 DowDuPont. All rights reserved. D u P o n t P h o t o v o l t a i c S o l u t i o n s 8

9 Module and backsheet requirements for Rooftop PV Application requirements Impact to module Requirement for Backsheet Fire safety Fire resistance Fire resistance applications (Tedlar as decoration of plane; building membrane structure ) Flame spread index (FSI), (Tedlar class A; AAA class B) Durability Ensure 25yrs lifetime and performance Long term field proven record Superior durability after various aging tests High Temp. High Temp. stability Melting point Thermal resistance (RTI; TI) Greater Temp. Range High TC resistance Strong mechanical properties in MD and TD directions Better co-efficient of thermal expansion (CTE) High Efficiency High Efficiency High reliability to ensure high efficiency output Aesthetics High UV Albedo for open rack installation Light Weight & Easy Installation Color stability; Different colors; New structure designs High Backsheet UV resistance Glass/backsheet structure; flexibility module; new designs Color stability Different colors High UV resistance Avoid to use glass backsheet except BIPV 2018 DowDuPont. All rights reserved. D u P o n t P h o t o v o l t a i c S o l u t i o n s 9

10 Safety First: Rooftop Solar Farm Accidents Caused Serious Losses A large DPV developer in China: 3 installations among ~200 had fire accidents in 2017; Germany had reported 75 rooftop solar farm fire accidents by 2014; Most of the accidents related to electrical faults or high temperature. D u P o n t P h o t o v o l t a i c S o l u t i o n s 10

11 Tedlar Has Exceptional Smoke/Fire Performance and Has Been Used in Aircraft and High-speed Trains Tedlar has US FAA and EU EASA Certifications and has been used in aircraft which have the highest fire-resistance requirements 2018 DowDuPont. All rights reserved. D u P o n t P h o t o v o l t a i c S o l u t i o n s 11

12 Rooftop PV Has the Highest Operating Temp. Between ground mounted and roof integrated installations, you should expect a 25 C operating temperature increase. Deficient cells and partial shading conditions add to the operating stresses and represent very significant safety risks. One can minimize the risk of low intensity hot spots by choosing more inherently resistant backsheets. Air Ground Open rack Close fit BIPV Source: Creep in Photovoltaic Modules: Examining the Stability of Polymeric Materials and Components (2010) 35th IEEE Photovoltaic Specialists Conference (PVSC 10) Honolulu, David C. Miller, Michael Kempe 2018 DowDuPont. All rights reserved. D u P o n t P h o t o v o l t a i c S o l u t i o n s 12

13 Shading or Defect can Cause Formation of Hot Spot Low CTE can help to reduce backsheet delamination under hot spot Bubble Cracking Burnt 2018 DowDuPont. All rights reserved. D u P o n t P h o t o v o l t a i c S o l u t i o n s 13

14 Hot Spots Caused Cracking/Bubbling/Burning in Field PVDF, 2yrs, USA PVDF, 3yrs, Israel FEVE coating, 2yrs, China Film softening Temp* Softening temp. of PVDF film is <160 o C Tedlar PVF Film Has 30~40 o C Higher Softening Temperature Than PVDF and Thus Better Hot Spot Resistance JIS K7196 Heat Deformation Test- weighted stylus impinges on sample being heated, thermal transitions noted 2018 DowDuPont. All rights reserved. D u P o n t P h o t o v o l t a i c S o l u t i o n s 14

15 PA-based and PET-based Backsheets Yellowing in Rooftop Solar Farms in Jiangsu, China 4 yrs field modules with PET or PA-based backsheets in one rooftop solar farm; >50% of PET-based backsheets and >10% of PA-based backsheets show front side yellowing issues associated with >2% annual module power degradation DowDuPont. All rights reserved. D u P o n t P h o t o v o l t a i c S o l u t i o n s 15

16 PVDF-Based Backsheet Cracking and Delamination Cracks evolving into delamination Cracked PVDF Remains of backsheet outer layer Significant level of PVDF degradation Starts with cracking Evolves into delamination and large area peel-off 2018 DowDuPont. All rights reserved. D u P o n t P h o t o v o l t a i c S o l u t i o n s 16

17 PVDF Film Brittleness in TD After Aging Created High Risk of Cracking 600 Film TD Elongation (%) After UV Aging Hours UVA 1000 Hours UVA PV 2001 PV 2025 PVDF 1 PVDF 2 PVDF 3 PVDF 4 Significant film elongation loss can result in backsheet cracking PV2001 and PV2025 are Tedlar PVF films 1000hrs UVA is 65 kwh/m 2 UV dosage and equals to ~6yrs UV irradiation on module rear side under desert climate. D u P o n t P h o t o v o l t a i c S o l u t i o n s 17

18 Long-Term Durability of Rooftop PV Installations Require a Reliable Rooftop! Distributed PV often is installed on industrial plants, public buildings, etc. which mainly use metal-color steel tile. This steel is easily corroded. Once the rooftop is corroded/damaged, there is a huge O&M cost to repair the rooftop or change the solar panels. The cost will strongly impact the lifetime and LCOE of the solar farm. Long-term durability of rooftop PV not only needs high quality PV materials, but also a reliable rooftop! 2018 DowDuPont. All rights reserved. D u P o n t P h o t o v o l t a i c S o l u t i o n s 18

19 Covered Steel Tile Covered with Tedlar Film Has 30+ yrs of Field-Proven Reliability Tedlar film covered steel tile wall in Japan (installed in 1984) Tedlar film covered steel tile wall in coal-fired power station in Okinawa, Japan (built in 1986). New installed, 2010 Original installed, 1984 DuPont plant rooftop (installed in 1983) Non-Tedlar steel tile, installed at the end of the 20 th century Tedlar film covered steel tile, installed in 1983 High-corrosion climate near the ocean. Power station was built in 1986 with steel tile covered with Tedlar film. After 27 yrs of service, the wall looks like new and there is no corrosion, not even at edge of the tile DowDuPont. All rights reserved. D u P o n t P h o t o v o l t a i c S o l u t i o n s 19

20 DuPont Polymer Mounting System (DPMS) is a lower substructure and lower installation cost solution than conventional rack mounting systems 270kW demo on DuPont (China) R&D Center, Shanghai

21 DuPont Photovoltaic Solutions Has More Over 40 Years Experience in PV - From Materials to Power Generation 2018 DowDuPont. All rights reserved. D u P o n t P h o t o v o l t a i c S o l u t i o n s 21

22 Thank You 2018 DowDuPont, The Dow Chemical Company, DuPont. All rights reserved. Trademark of DowDuPont, The Dow Chemical Company, E.I. du Pont de Nemours and Company, or their affiliates.