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SunPower Cell & Module Technology overview
Stefano G. Alberici, PhD, Sr. Trainer EU,
SunPower Corporation
New Delhi, 17.10.2012, Rooftop Workshop India
2 PV classical stereotypes…:
“Come on: A module is a module: they are
all the same. The only thing that counts is
the price. Why should I bother with other
items?”
“Come on: A kWp is a kWp: they are all
the same. Their production (kWh/kWp/y)
does not change when changing the
module. The only thing that counts is the
price. Why should I bother with other
items?”2
Most powerful PV modules in the market
Why you should bother? Here is why:SunPower – a differentiated technology
Industry leading panel efficiency: 20%, leading cell efficiency: 22,5%
Produce up to 50% more than conventional panels and up to 4 times more
than thin film panels per unit area
Best energy performance (kWh/kWp), averaged +7 to +9 %/y more than the rest of PV
Solid reliability & quality
Industry’s first 25-year combined power and product warranty
3
Maxeon
Technology
SunPower technology is better
444
Mo
du
le E
ffic
ien
cy
Standard
Efficiency
(16% cell)
HiT
(20% cell)
Selective
Emitter
(19% cell)
SunPower
E-Series
(22.5% cell)
20%
18%
16%
14%
14%
44
16%
19%
20%
22%
12%
Thin Film
CdTe
(12.2% mod)
Maxeon
Technology
Conventional solar: warranty returns
Reliability of PV Systems. J Wohlgemuth. Proceedings of SPIE, presented 11-August-2008
86% of conventional solar panel warranty
returns:corrosion / cell /
interconnect breaks
Maxeon
Technology
5
Front contact cellsSunPower Cell
Back side copper plating provides significant degradation advantage
Plated interlaced copper conductors
Ductile metal provide much more strength to the Silicon
Even if the Silicon cracks, the copper fingers maintain full conductivity, so a cell crack causes no loss of cell area and no measureable power drop.
Copper/tin plating is very robust against corrosion, and very easy to solder
Screen-printed metal paste
The baked-on paste offers no structural strength… all the strength is from the brittle Silicon wafer itself.
Very thin silver front-side metal lines oxidize/corrode over time
Lines are
alternating
(+) and (-)
copper
conductors
Maxeon
Technology
6
SunPower returns rate from 2006 to 2012:
33 ppm (200 / 6 milions)
Most efficient cells in the industry
7
SunPower Cells
22.5% efficiency
Conventional cells
Monocrystalline 15-17% efficiency
Conventional cells
Polycristalline 14-16% efficiency
SunPower cells are up to 50% more efficient than conventional
solar cells due to unique all-back contact design
Maxeon
Technology
Conventional Design Breakthrough Design
Stronger Materials
Front
Contact
Cell
Compared to SunPower Maxeon cell technology
Back
Contact
Cell
Conventional Monocrystaline
Technology
SunPower Maxeon
Cell Technology
More metal on the back = Higher durability & toughnessBack contacts = robust cell to cell connection & long-term operating lifeNo shading losses
Maxeon
Technology
SunPower panels produce up to 50% more power per m2
13
20%
19%
18%
17%
16%
15%
14%
13%
12%
SunPower
Panasonic
Sanyo
SunTech
SolarWorld RECKyocera
Solar Sharp BP Solar
As published in Photon International, July 2011
Highest Panel Efficiency by Manufacturer
Maxeon
Technology
15
Voltage builds rapidly at low insolation levels
Better performance in overcast conditions
Inverter wakes up earlier and runs later
Better low-light performance
SunPower SPR-90
Mono Crystalline Silicon
Poly Crystalline Silicon
CuInSe2
Amorphous Silicon
SunPower solar cells
generate more power at
low light levels relative to
other technologies
Sharper knee of curve at low light
levels is indicative of better low
light performance
Maxeon
Technology
Comparison SunPower vs. non SunPower:the effect of the Anti-Reflecting Glass on panels
16
NON SPWR
NON SPWR SPWR
Maxeon
Technology
Higher performance at higher temperatures
17
Due to lower temperature
coefficients and lower normal cell
operating temperatures (NOCT),
SunPower panels generate more
energy at higher temperatures
compared to standard c-Si
modules
Temp Coefficient:
SunPower -0.38% / °C
Std c-Si -0.47% / °C
NOCT:
SunPower 45 °C +/-2
Std c-Si 47 °C +/-2
0 5 10 15 20 25 30 35 40
(C°)
Maxeon
Technology
Operating temperatures: SPRW vs. standard c-Si
18
Higher efficiency modules operate at lower temperatures because they convert more
of the sun’s energy to electricity – lower efficiency modules convert it to heat instead
Temperature
difference
Time (h)
Maxeon
Technology
Highly accelerated life test (HALT)
Solar Simulator Dynamic Load
Test
Damp Heat TestAutoclaveUV Tester
Maxeon
Technology
Dynamic Load Test Results
CompetitorPower Loss = 2.1%
SunPowerPower Loss = 0%
Electroluminescence images of a front-contact module and SunPower back contact module
after dynamic load HALT stress (1000 cycles of +/-2400 Pa, equivalent to maximum wind
load, of alternating pressure load on the glass)
Maxeon
Technology
Reliability testing data: damp heat
SunPower cells are highly resistant to corrosion
22
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
110%
0 1000 2000 3000 4000 5000 6000 7000 8000
Po
we
r D
egr
adat
ion
Number of Hours
Performance of SunPower and Traditional Front Contact Modules in Damp Heat (85°C, 85% RH)
SunPower
1
2
3
4
5
6
7
Maxeon
Technology
SunPower performs better in hot arid climates
University of Arizona / Tucson Electric Test Yard
SunPower panels generate 8% more energy than the average of the rest of the field
For current SunPower panels: add 1-3% for AR glass plus 1% for rooftop temps
8%
11% more energy output
Cronin, Alexander, et. al. “Performance Reviews from the Tucson Electric Power Solar Test Yard,” 2011 data update.
23
Maxeon
Technology
6.2%
Average 9% more energy outputin third-party Energy Yield Studies
3rd party study compilation
Compilation of 10 large studies shows SunPower yield is well above the average mono- and poly-crystalline silicon PV Panel yield.
For current SunPower panels: add 1-3% for AR glass plus 1% for rooftop temps
Rose, Doug, et. al. “High-Confidence Prediction of Energy Production fro High-Eff PV Systems,” 25th PVSEC Valencia, Sept. 2010.
24
Maxeon
Technology
Industry’s first 25-year combined power and product warranty
POWER GUARANTEE
– More Power: at least 95% of the Minimum Peak Power for the first five years
– Less than 0.4% annual degradation for the subsequent 20 years
More lifetime energy: 9.1% above the industry standard
PRODUCT WARRANTY
– The solar industry’s first 25 year product and power coverage
– Coverage of warranty replacement costs
– Financial stability and product reliability to back our commitment
26
Maxeon
Technology
27
70
75
80
85
90
95
100
0 5 10 15 20 25
Gu
ara
nte
ed
no
min
al
P (
%)
Years of performance
Industry Standard SunPower Previous Warranty
Power warranty: what’s new
Industry Standard Previous
SunPower Warranty
NEW
SunPower warranty (as from July 1st)
Step:
90%: 10 years
80%: 25 years
Step:
90%: 12 years
80%: 25 years
Linear:
95% for 5 years
Year 6 – 25: -0.4%/yr
Power
warrantyProduct
warranty
SunPower New Linear Warranty
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
Industry leading 25-year product warranty
28
SunPower
Industry Standard Previous
SunPower warranty
The NEW
SunPower warranty (as from July 1st)
5-10 years 10 years 25 years
Jinko Solar
Kyocera NA
Solarworld, Sharp, First Solar,
Suntech, Canadian, Trina, Yingli
Hanhwa
Power
warrantyProduct
warranty
Years of performance
*Source: Companies’ websites & datasheets. Data as of 15 September 2012