Acceleration of Degradation by HAST and air-HAST … · Acceleration of Degradation by HAST and...
Transcript of Acceleration of Degradation by HAST and air-HAST … · Acceleration of Degradation by HAST and...
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Acceleration of Degradation by HAST and air-HAST in c-Si PV Modules
Tadanori Tanahashi2, Soh Suzuki1, Takuya Doi2, and Atsushi Masuda2 (1ESPEC CORP., 2AIST)
SAYURI-PV 2016 (Tsukuba, JP) 2016/10/4
Main parts of this presentation have been published in The Japanese Journal of
Applied Physics, Vol. 55, No. 2, p. 22302, Feb. 2016.
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EL Images of c-Si PV Modules Exposed in Identical Outdoor Site (ca. 30 Years)
Mfg. in 1983 Pmax: -40.5% Isc: -19.0% Voc: -1.2% FF: -25.6% (vs. Name Plate)
Mfg. In 1984 Pmax: -43.9% Isc: -9.5% Voc: -0.6% FF: -31.7% (vs. Name Plate)
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% C
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ge o
f IV
Par
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Model: a Model: g Model: d Model: e Model: f Model: b
% Changes of PV Parameters in Long-Term Exposed c-Si PV Modules under Outdoor Conditions
Large Reduction of Isc & FF
A Little Reduction of Voc
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0.2
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ize
d P
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A-1 B-1 C E F G H I J K M N 0
Massive Survey for the Degradation Profiles of Commercial PV Modules Extended Damp Heat Test: 13 Models (multi- / mono-c-Si, FY2011~)
Initial Value
DH: 1,000 h
DH: 2,000 h
DH: 3,000 h
Mean +/- SD (N = 10 or 5)
5% P / F Criteria
Asia Standards and Conformity Assessment Promoting Project (METI), 2011-2014
Mono-c-Si
Multi-c-Si
4
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0 1000 2000 3000
Pmax
Isc
Voc
FF
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Massive Survey for the Degradation Profiles of Commercial PV Modules Extended Damp Heat Test: 13 Models (multi- / mono-c-Si, FY2011~)
Asia Standards and Conformity Assessment Promoting Project (METI), 2011-2014
Model C Model I Model E
Duration of DH Test (h)
No
rmal
ize
d P
V P
aram
ete
r
Large Reduction of Isc & FF
A Little Reduction of Voc Similar Reduction
with those Observed in Outdoor Exposed PV Modules
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Motivation
Hygrothermal Stress Test defined in IEC 61215: 10.13 Damp Heat Test: 85oC / 85% rh, 1,000 h
“To determine the ability of the module to withstand the effects of long-term penetration of humidity”
Moisture Ingress (Penetration of Humidity): -> Corrosion, Delamination, Discoloration, Loss of Elasticity / Adhesion in Polymer Materials, and Other failures ====> Power Loss of PV Modules (> 2,000 h)
Objectives To Precisely Address the Effects of Hygrothermal Stress (i.e., Identification of Power-Loss Mechanisms) To Establish a Novel-Accelerating-Hygrothermal Stress Test (Time Saving, Actual Stress reflecting field exposure)
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Encapsulant (EVA)
Glass
Encapsulant (EVA) PV cell
Backsheet(T / P / T)
Mini-Module Architecture
No Frame / No Edge Seal
= practically “No Guard” to Moisture Ingress
Mini-Module (1 cell)
Experiment: c-Si PV Mini-Module
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Power Loss with Hygrothermal Stresses
Time (h)
D P
max
(%
)
Mean +/- Std. Error
85 / 85
95 / 95
HAST 105 /100
HAST 120 /100
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Artificial Degradation in HAST: 120 / 100 (200 h)
PVF (T)
PET
PVF (T)
EVA Module Architecture
Delamination of Backsheet Component(s)
EVA
Glass
EVA PV cell
Backsheet(T / P / T)
View from Backside of PV Module
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Temp. (oC)
Humid. (% RH)
Total Pressure(kPa [A])
Water Vapor P. (kPa [A])
Air Pressure (kPa [A])
Air P. / Water V. Ratio
Air P. / Total P. Ratio
Atmos. 25 60 101.3 1.6 99.7 62.3 0.98
DH 85 85 101.0 49.2 51.8 1.1 0.51
HAST
105 100 120.8 120.8 0 0 0
110 85 121.6 121.6 0 0 0
120 100 198.5 198.5 0 0 0
air-HAST
110 85 249.8 121.6 128.2 1.1 0.51
These values (Pressures, Ratios) are calculated from ideal gas composition.
Hygrothermal Conditions (DH, HAST, air-HAST)
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HAST / air-HAST
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Power Loss under DH / HAST / air-HAST Stress Conditions
Jpn. J. Appl. Phys. 55 (2): 22302, 2016
Rate of Power-Loss in HAST and air-HAST was ca. 5-Folds that in DH Stress Test.
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Correlation of Power Loss (ΔPmax) with the Decreases in PV Parameters (ΔVoc, ΔIsc, and ΔFF)
Voc
Voc
Isc
Isc
FF
FF
Jpn. J. Appl. Phys. 55 (2): 22302, 2016
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I–V Curves for Three hygrothermal Stress Tests
DH 85/85 air-HAST110/85 HAST 110/85
In severe degraded conditions, n (diode factor) is Over 2, due to Non-Uniform Contact Resistance .
Ref: A. S. H. van der Heide, A. Schönecker, J. H. Bultman, and W. C. Sinke, “Explanation of high solar cell diode factors
by nonuniform contact resistance,” Prog. Photovoltaics Res. Appl., vol. 13, no. 1, pp. 3–16, Jan. 2005.
Jpn. J. Appl. Phys. 55 (2): 22302, 2016
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Dark I–V Curves at 0 and 800 h after HAST or air-HAST
Jpn. J. Appl. Phys. 55 (2): 22302, 2016
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Jpn. J. Appl. Phys. 55 (2): 22302, 2016
Contents of Acetate Ions in the Peripheral and Central Encapsulant Regions of PV Modules
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Jpn. J. Appl. Phys. 55 (2): 22302, 2016
Visual Images of PV Modules after the Exposure to DH stress, HAST, or air-HAST
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1 2
3 4
5
1 2
3 4
1 2
3 4
5
Colorimetric Positions in c-Si PV Module
Front w/o Cell
Front w/ Cell
Rear
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Brightness : z Difference in Saturation: r Hue: f
Color Difference Level = Distance (d)
L*a*b*Color Space Cylindrical (Axis) System Rectangular Coordinate System
A = Origin B = Terminal
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Jpn. J. Appl. Phys. 55 (2): 22302, 2016
Discoloration in the Front Sites w/o Cell of tested PV Modules
A = Origin (Initial State)
DH
HAST
air-HAST
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Jpn. J. Appl. Phys. 55 (2): 22302, 2016
Increase in Distance (d) in PV modules during the Exposure to DH stress, HAST, and air-HAST Conditions
DH – air-HAST: Apparent Acceleration Factor (AF) Identified by Discoloration Rates in All Sites was Approximately 10-Folds.
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Jpn. J. Appl. Phys. 55 (2): 22302, 2016
Brightness (z) Hue (f) Saturation (r)
Changes in three color attributes (z, f, and r) in PV Modules during the Exposure to DH stress, HAST, and air-HAST Conditions
Front w/o Cell
Rear
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http://dx.doi.org/10.1016/j.polymdegradstab.2013.06.024
in HAST Condition: Inert Conditions due to Exhaust of Air Thermal Oxidation of EVA is Completely Restricted by Inert Conditions
in DH / air-HAST conditions: Oxygen penetrated into EVA Thermal Oxidation of EVA was Occurring with the Penetrated Oxygen
DLO: Diffusion Limited Oxidation M. C. Celina, “Review of polymer oxidation and its relationship with materials performance
and lifetime prediction,” Polym. Degrad. Stab, vol. 98, no. 12, pp. 2419–2429, 2013.
We assume that the ‘Thermal Oxidation’ of EVA proceeded under DH / air-HAST conditions, but not under HAST condition
Of Course, Thermal Oxidation is a Common Reaction Observed in Outdoor Conditions Then, We Should Address the Precise Effect of Oxygen on Discoloration of EVA
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Summary
- air-HAST (110 oC/85% rh, containing air) can accelerate the power-loss,
the accumulation of acetate ions in the front EVA, the discoloration of the encapsulant
similarly to the DH stress test (85 oC/85% rh).
- HAST (110 oC/85% rh, non-containing air) can accelerate the power-loss,
the accumulation of acetate ions in the front EVA, the discoloration of the encapsulant
similarly to the DH stress test (85 oC/85% rh).
- The required duration of the DH stress test will at least be significantly shortened using air-HAST, but not HAST.
X
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