Lowering the LCOE of Photovoltaic Systemsucsolar.org/files/public/documents/12-9-11 present...
Transcript of Lowering the LCOE of Photovoltaic Systemsucsolar.org/files/public/documents/12-9-11 present...
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Lowering the LCOE
of Photovoltaic Systems
Levelized Cost of Energy
Methods to reduce the LCOE
PV Researches at UC Merced
Yong Sin “Shon” KimDec. 09 2011
School of Natural Science, University of California at [email protected]
http://ucsolar.org
2011 UC Solar Research Symposium
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Cost of EnergyCost of Energy
• System: $/MWh (₡/KWh)• Components: $/W
Credit: California Public Utilities Commission
PG&E Average Bundled Rates by Class
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Levelized Cost of Energy (LCOE)Levelized Cost of Energy (LCOE)
• Definition– The unit cost of energy generated over its economic lifetime.
• Widely used to compare different technologies
• Calculation
where r1 is a system degradation rate and r2 is a discount rate.
Ref: International Energy Agency, ‘Projected Costs of Generating Electricity’ (2010)
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Levelized Cost of EnergyMethods to reduce the LCOEBy a Material scientist
By a Optic designer
By a Electrical engineer
By a System engineer
PV Researches at UC Merced
Yong Sin “Shon” KimDec. 09 2011
School of Natural Science, University of California at [email protected]
http://ucsolar.org
2011 UC Solar Research Symposium
Lowering the LCOE
of Photovoltaic Systems
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What a Material Scientist doesWhat a Material Scientist does
• Cost ↓
• Efficiency ↑
• Acceptance angle ↑
• Degradation ↓
Credit: NREL
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Thin film/silicon based PV –Concentration : 1x–Wide acceptance angle– Low efficiency–Temperature coefficient:
• Thin film ~ ‐0.2%/K• Silicone based ~ ‐0.4%/K
Concentrating PV–Concentration
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High Efficiency ModuleHigh Efficiency Module
• CPV highest efficiency
Credit: SolFocus
Higher efficiency lower LCOE?
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Proper PV Systems around the WorldProper PV Systems around the World
Latitude(°)
Lo
ng
itud
e ( °
)Annually averaged DNI(kWh/m2/day)
-180 -120 -60 0 60 120 180-90
-60
-30
0
30
60
90
0
1
2
3
4
5
6
7
8
9
Silicon PV Thin film CPV
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• Maximum power point tracking– Either embedded into inverters or controlled separately– Tracking efficiency > 99.8%
• Inverter Efficiency– Power Electronics is matured area– Maximum Efficiency > 98%
• Reducing the cost– Reducing the cost of each components
What an Electrical Engineer doesWhat an Electrical Engineer does
Ref: International Energy Agency, ‘Projected Costs of Generating Electricity’ (2010)
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Power Optimization RoadmapPower Optimization Roadmap
Source: SMA
Source: SMA
?Source: NSC, Enphase, SolarEdge
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Distributed PV SystemsDistributed PV Systems
• Enphase• SolarMagic
• Ref: SolarMagic.com, enphase.com
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SunPower Embraces Microinverters SunPower Embraces Microinverters
• SunPower offers AC solar panels with 25‐Warranty (Oct. 17, 2011).
• Enphase has strengthened the warranty of its microinverters to 25 years
• A panel with a micro inverter vs a panel and a micro inverter
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• Capacity factor• Ground coverage ratio
What an System Engineer doesWhat an System Engineer does
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Levelized Cost of Energy
Methods to reduce the LCOE
PV Researches at UC Merced
Yong Sin “Shon” KimDec. 09 2011
School of Natural Science, University of California at [email protected]
http://ucsolar.org
2011 UC Solar Research Symposium
Lowering the LCOE
of Photovoltaic Systems
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Smart Monitoring SystemSmart Monitoring System
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• Short circuit current of individual cells
• Currently working on defining–The series resistance Rs
• Partial masking techniques–Previous works define
• Rsh and Isc
Characterizing individual cell in a moduleCharacterizing individual cell in a module
123456
Row
2.5
2.6
2.7
1 2 3 4 5 6 7 8 9 10 11 12123456
Column
Row
4.2
4.3
4.4
50% masked
20% masked
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Mismatch LossMismatch Loss
• Distributed MPPT– MPPT for each module– ±5% mismatch : 3.34%– ±10% mismatch : 5.78%
• String level MPPT – 6 modules in series– ±5% mismatch : 4.00%– ±10% mismatch : 8.24%
4.6 4.7 4.8 4.9 5 5.1 5.2 5.3 5.4
0.0050.01
0.050.1
0.25
0.5
0.75
0.90.95
0.990.995
Data (A)
Pro
babi
lity
dens
ity
5%10%
These cells limit the string current
0.050.1
0.25
0.5
0.75
0.90.95
Pro
babi
lity
dens
ity
4.6 4.7 4.8 4.9 5 5.1 5.2 5.3 5.4
0.050.1
0.25
0.5
0.75
0.90.95
Data (A)
Pro
babi
lity
dens
ity
10% Mismatch
5% Mismatch
Mismatch is assumed to normal distribution with 3σ at 5% or 10% of their mean value
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SelfSelf‐‐shading Lossshading Loss
0
0.5
1
1.5
2
2.5
3
Po
we
r o
f (a
) (K
W)
Centralized
String
AC ModuleDC Module
w/o MPPT
0 0.2 0.4 0.6 0.8 10
0.5
1
1.5
2
2.5
3
Fraction of self-shading
Po
we
r o
f (b
) (K
W)
Centralized
String
AC ModuleDC Module
w/o MPPT
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• UBS–Fast tracking–No oscillation–No ad hoc parameter
• Problems of previous methods–Slow tracking–Oscillation–ad hoc parameters
Unbounded Binary Search for MPPTUnbounded Binary Search for MPPT
Patent Pending
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• Fixed voltage scheme–Sets the voltage that inverter has its maximum efficiency
• Fixed current scheme–Uses the reference module w/o MPPT
• AC output sensing–Maximize ac power
Inverter in a Distributed SystemInverter in a Distributed System
Y.S. Kim, S.M. Kang, R. Winston: submitted to ISCAS12
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• Shading diagram–The darker the color, the more the place is shaded.
• CPV trackers installed at UC Merced
Shading by a Tracker ArrayShading by a Tracker Array
North-south Spacing(m)
Eas
t-w
est S
paci
ng(m
)
-10 0 10 20 30
0
5
10
15
20
25
Ref: Kim, Y. S., Kang, S.‐M. and Winston, R. (2011), Modeling of a concentrating photovoltaic system for optimum land use. Patent Pending
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Performance (Performance (±±5% mismatch)5% mismatch)
• Tracker array– Single tracker – w/o self‐shading
• Module array– 3‐by‐4 modules
• Optimum distance @GCR=0.2– ΔX(NS)=11m– ΔY(EW)=9m
0 5 10 15 20 250
10
20
30
40
50
Local time (H)
To
tal p
ow
er
(KW
)
CentralizedStringAC ModuleDC Modulew/o MPPT
w/o MPPT Centralized String DC module2‐by‐2 0.938 0.965 0.975 0.9963‐by‐3 0.908 0.960 0.973 0.9954‐by‐4 0.885 0.957 0.973 0.9955‐by‐5 0.871 0.955 0.972 0.994
Ref: Kim, Y. S., Kang, S.‐M. and Winston, R. (2011), Modeling of a concentrating photovoltaic system for optimum land use.
Normalized performance to AC module (micro inverter)
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ConclusionConclusion
System Engineers
Thank You