Power Rating of Multi-junction Solar Cells: Focus Thin Film

Transcription

Power Rating of Multi-junction Solar
Cells: Focus Thin Film
Content:
1. Basics of current matching – a short review
2. Requirements on Solar Simulator
3. Status of Test labs concerning thin film tandem
Prof. Dr. Franz Baumgartner, ZHAW, 2010-04-22, Solarpraxis Berlin; [email protected]; https://home.zhaw.ch/~bauf/
1
Measurement of the Current Voltage
Characteristics of Standard PV Modules
Single Junction
Swiss Mobile Flasher Bus comes to the plant site,
high number of samples up to 100 a day
www.ekz.ch/solarlab
Maximum Power
Pmp
F. Baumgartner, EUPVSEC, Hamburg Sept 2009
Franz Baumgartner, www.engineering.zhaw.ch/en/ ; 2010-04-22; Solarpraxis Berlin,
Slide 2
Standard Method of PV Power
Measurement
Device under Test
I STC = I DUT ,meas
PSTC
PREF ,meas
⋅ SMMF
IEC 60904-7 Mismatch correction
STC Standard Test Conditions
AM1.5 Spectra, 1000 W/m2, 25°C
Flash
light
Typical today's Measurement Uncertainty
of typ. 2 to 3% (k=2) at the best test labs
possible for single junction cr-Si Modules
Reference Cell
(costs about 100 to 500€ / per test incl. logistics)
Slide 3
Stability +/-1%, Flasher Pulse
IV Curve Measurement
Internal Data from Corina Droz, Pasan; 15. Dec 08
Slide 4
Power Tolerances of PV modules
Standard cr-Silicon Modules
Manufactures PV Modules Datasheet: high eff. Si
- 5%
- 10%
199.5W 205W
Data sheet 09/09
210W
Nominal
power
231W
Manufactures PV Modules Datasheet: poly cr. Silicon
Power tolerance +/-3%
+ Sorting: flasher report
- 3%
PN [W] 200
Power Warrenty 25 years
Slide 5
205
- 3%
210
215
Nominal
power
220
225
230
Law in action - To go to court?
Manufacturers Datasheet: 210W (+/-3%) Tolerance
Effective
Tolerance
-5%
204
210
216
Independent Testlab Results: 201W (+/-2% uncertainty k=2)
-u(T)
+u(T)
205W > guaranteed upper limit 204W
Justice decision: The independent test result can not prove that
manufactures data specification failed! Result: OK !! Effective Tolerance (+/-5%)
Testlab Results failed if below ( datasheet tolerance + testlab uncertainty)
Slide 6
PV World Market and Uncertainty
of nominal Power
Turnover 2008 PV Module end customer 15 000 Mio €;
2% uncertainty in Pn ► 300 Mio €
Installations Europe 4800 MW
Only Thin-film Production Capac.
A. Jäger-Waldau; Aug 2009; ISBN 978-92-79-12800-4; http://re.jrc.ec.europa.eu/refsys/
Slide 7
Spectral Characteristics /PV Technologies
of single junctions / single band gap cell
H. Mulejans, JRC, EUPV Conf 2008, Valencia
Slide 8
4) Solar Spectra: Spectral Mismatch Factor
MMF
SR
∫
=
∫ SR
DUT
DUT
( λ ) ⋅ E eSTC ( λ ) ⋅ d λ ⋅ ∫ SR REF ( λ ) ⋅ E eIN ( λ ) ⋅ d λ
( λ ) ⋅ E eIN ( λ ) ⋅ d λ ⋅ ∫ SR REF ( λ ) ⋅ E eSTC ( λ ) ⋅ d λ
Slide 9
Quelle: http://www.hmi.de/pr/bildarchiv/solarenergie/grafiken, 18.03.2009
Singel cell’s and tandem cell’s
energy lift
Tandem cell
Standard single bandgap
red photon
red photon
blue photon
blue photon
Single cell Eg1
Output
2e-
- -
-
Voc ~2/3 Eg1/e
-
Energy level of the electron
-
Top cell
Eg2
-
Bottom cell
Eg1
Output
1eVoc ~2/3 Eg1/e
+ 2/3 Eg2/e
higher voltage!
Slide 10
-
Simple model of the tandem cell –
circuit schema / multi-junction
BOTTOM CELL LIMITIED SPECTRA at Vm=0V
TOP CELL LIMITIED SPECTRA at Vm=0V
Im
Im
Isc_top
Isc_top
Im
Im
Isc_bot
Isc_bot
•
The photo generated currents of the bottom and the top cells are different in real tandem cells, due to
each specific spectral cell response behaviour exposed to the given light spectra.
•
One serial resistance and two parallel resistance complete the simple model
Slide 11
IV of tandem cell
IV-curve tandem cell - serial connected
0.4
bottom cell
top cell
tandem V_top+V_bot
0.2
0.0
current [A]
-1
-0.5
0
0.5
1
1.5
-0.2
IV curve at
Vm=0V
limited by
bottom cell
V_bottom_cell
V_bottom_cell
-0.4
-0.6
-0.8
Isc of the tandem cell is limited by
the Isc of the bottom cell
(or reverse IV characteristics)
-1.0
voltage [V]
Cell with the smallest Isc dominates terminal Isc (it no reverse break through).
Slide 12
1. Conclusion: Current Limit
• The current at maximum power of the tandem-cell is limited by
the lowest short circuit current of the sub-cells.
Slide 13
Indoor have to adapted for
outdoor spectra
F.P. Baumgartner et. al.; EUPVSEC Dresden 2006
Slide 14
Spectra and Top/Bottom Cell Performance
K. Yamamoto, Kaneka, Osaka PV Conf (2003)
Slide 15
Current matching high eff. cells
InGaP / GaAs
Current
matching
Patent US20040187912, Sharp 2004
Slide 16
2. Conclusion: Thickness design
• The effective optical thickness of the top and bottom cell is the
most important design parameter in a-Si/uc-Si Tandem cell to
reach current matching
(Remark: light trapping has an important effect on current
matching and my change by the angle of irradiance on the
module plane)
Slide 17
Output tandem cell: GaInP/GaInAs
Ga0.65In0.35P/Ga0.83In0.17As
Slide 18
Next Generation Photovoltaics; High efficiency through
full spectrum utilization; ISBN 0 7503 0905 9; ( 2004)
Antonio Mart´ ı and Antonio Luque;
Current Matching: a-Si/uc-Si Tandem
Light-soaking
Slide 19
Seasonal Spectral Change at Noon
Slide 20
Changing Temperature
at the a-Si/uc-Si Tandem
Slide 21
3. conclusion: Real life!
The current matching at STC conditions AM 1.5 will not be
reached in real outdoor operation due to
1. Change in Temperature and the inherent different temperature
coefficients of the sub-cells
2. Spectral changes of sun light due to sun heights (AM 1.5) and
different clouds
3. Unstable sub-cell: light soaking of the a-Si Top cell
4. Light trapping and thus current matching my change at different
angle of irradiance
IEC 61853 „Energy Rating of PV Modules“ have to be modified
Slide 22
Requirements on nominal power
measurement!!
The goal is to have all the relevant data to predict the kWh
electricity production after 25 years! (IEC norms not ready!)
•
Pn Test at one spectra is not enough!
- daily and seasonal changes of sun spectra
- power characteristics as a function of air mass Pm=f(AMxx)
this requires a sun simulator with adjustable spectra!!
•
Temperature coefficient of different matching conditions at
least for bottom or top cell limitation condition have to be given
•
Pn test results just after module fabrication is not enough:
the degradation / light soaking has to be taken into account
•
The spectral characteristics of each sub-cell have to be known
to reduce measurement uncertainty
Slide 23
The optimal light source
and the optimal reference cells
• Solar Flasher Simulator have to fit excellent to AM 1.5
but have to have the potential to shift the spectra to the blue
and to the red. This could by realised either continuously
(additionally filter arrangement) or in discrete steps by the
use of additional light sources like LED’s
• SMMF Spectral mismatch factor have to be applied to the
limiting sub-cell ∫ SR (λ ) ⋅ E (λ ) ⋅ dλ ≠ ∫ SR (λ ) ⋅ E (λ ) ⋅ dλ
TOP
eIN
BOT
eIN
• For each junction of the DUT a spectral fitted reference cell
should be used; for example a-Si/uc-Si
a-Si: (1 filtered cr-Si cell for the top cell i.e. KG3 filter)
uc-Si: (1 filtered cr-Si cell which represent the spectral input
of the bottom cell, extracting the photons absorbed by the
top cell)
Slide 24
High-Fidelity Solar Simulators
AIST Japan
National Institute of Advanced Industrial Science and Technology (AIST)
Yoshihiro Hishikawa and Sanekazu Igari, EUPVSEC Paris, 2004
Slide 25
Tandem moduls:
Status of the PV Test labs
• OUTDOOR Measurements are not different from the standard
setup; High qualified labs believe mostly in outdoor technique to
reach lowest uncertainties (i.e. JRC) measurement takes time!!
• OUTDOOR is no option for industrial production lines with high
throughput
• A few labs in central Europe give uncertainty values for tandem
cells in the range of 3 to 6% (up to 10% for triple cells)
• Select other light spectra than AM1.5 is tested in “fewer” labs
• Figure of merit of Tandem cells current-matching are not
discussed up to now in detail ( AMxx at matching)
Slide 26
Nominal Power and current matching
this 3 tandem modules have the same STC Power
η
PN,STC
AM x1
matching
coeff
blue rich
AM x2
matching
coeff
AM x3
matching
coeff
AM1.5G
Slide 27
red rich
Conclusion
• Up to know most of the most experienced test labs are working
on special indoor test procedures to measure the power of
tandem solar cells
• Measurement uncertainties below 5% are not expected today!
(only in a few selected Labs)
• Nominal power at AM1.5 and the “matching factor – optimum at
AM xx” should be given
• To predict yearly energy performance the low irradiance
characteristics of the tandem cell have to be known. (The
current mismatching at the changing spectra relative to AM
1.5G at low irradiance have to be taken into account)
Slide 28

Power Rating of Multi-junction Solar Cells: Focus Thin Film

Transcription

Similar documents

BerLin UrBAn Living- De ZwArTe HonD ArcHiTecTs

Cannabis `no worse than junk food`

BH_project_BeMobility, Berlin Elektromobil 2

berlin festival - Eran Troy Danner

140516_Beitragsservice ARD

SUMMER 2016

season`s greetings - happy new year

Worldmusic presented by Johannes Heretsch aka DJ Globalution

Student Matinee Study Guide COPPÉLIA

Whatl Saw