1. SOLAR ENERGY: A Path to Energy Significance 4/12/12
DISPERSED PV GENERATION:
SOLAR RESOURCE VARIABILITY
Richard Perez
Tom Hoff

2. DISPERSED PV GENERATION:
SOLAR RESOURCE VARIABILITY
SPATIAL
© R. Perez & T. Hoff

3. TEMPORAL TIME SCALE
© R. Perez & T. Hoff

4. 0
200
400
600
800
1000
1200
1400
One-Minute Global Irradiance (W/sq.m)
0
200
400
600
800
1000
1200
One-Minute Global Irradiance (W/sq.m)
-100%
-80%
-60%
-40%
-20%
0%
20%
40%
60%
80%
100%
Minute-to-Minute Change (%maximum yield)
-80%
-60%
-40%
-20%
0%
20%
40%
60%
80%
Minute-to-Minute Change (%maximum yield)
SINGLE LOCATION
20 UNCORRELATED LOCATIONS
© R. Perez et al
Relative Variability = 1/√N
N locations
© Richard Perez / Tom Hoff
Variability = σ(∆kt*)

5. 0
200
400
600
800
1000
1200
One-Minute Global Irradiance (W/sq.m)
-80%
-60%
-40%
-20%
0%
20%
40%
60%
80%
Minute-to-Minute Change (%maximum yield)
20 UNCORRELATED LOCATIONS
© R. Perez et al
© Richard Perez / Tom Hoff
Relative Variability = 1/√N
N locations

6. © Richard Perez / Tom Hoff
16 Months of data -- 40 million data points
© R. Perez & T. Hoff

7. Virtual Networks
Time  space = f (cloud speed)
© Richard Perez / Tom Hoff
400x400km satellite-
derived hi-resolution
one-minute data
16 Months of data -- 40 million data points16 Months of data -- 4 Billion data points
Very high density
modular networks
66 stations

8. -0.2
0
0.2
0.4
0.6
0.8
1
0 5 10 15 20 25 30 35 40 45 50
∆Kt*Correlation
Site-pair distance distance (km)
One minute
One minute
© Richard Perez / Tom Hoff

9. -0.2
0
0.2
0.4
0.6
0.8
1
0 5 10 15 20 25 30 35 40 45 50
∆Kt*Correlation
Site-pair distance distance (km)
One minute
5-minutes
© Richard Perez / Tom Hoff

10. -0.2
0
0.2
0.4
0.6
0.8
1
0 5 10 15 20 25 30 35 40 45 50
∆Kt*Correlation
Site-pair distance distance (km)
One minute
5-minutes
15-minutes
© Richard Perez / Tom Hoff

11. -0.2
0
0.2
0.4
0.6
0.8
1
0 5 10 15 20 25 30 35 40 45 50
∆Kt*Correlation
Site-pair distance distance (km)
One minute
5-minutes
15-minutes
30-minutes
© Richard Perez / Tom Hoff

12. -0.2
0
0.2
0.4
0.6
0.8
1
0 5 10 15 20 25 30 35 40 45 50
∆Kt*Correlation
Site-pair distance distance (km)
One minute
5-minutes
15-minutes
30-minutes
One Hour
HAWAII LAND Nov 2011
CLOUD SPEED 13 km/h
© Richard Perez / Tom Hoff

13. NEVADA Jun 1998
CLOUD SPEED 24 km/h
-0.2
0
0.2
0.4
0.6
0.8
1
0 5 10 15 20 25 30 35 40 45 50
∆Kt*Correlation
Site-pair distance distance (km)
One minute
5-minutes
15-minutes
30-minutes
One Hour
© Richard Perez / Tom Hoff

14. HAWAII Dec 2010
CLOUD SPEED 26 km/h
-0.2
0
0.2
0.4
0.6
0.8
1
0 5 10 15 20 25 30 35 40 45 50
∆Kt*Correlation
Site-pair distance distance (km)
One minute
5-minutes
15-minutes
30-minutes
One Hour
© Richard Perez / Tom Hoff

15. CENT. CALIFORNIA Mar 1998
CLOUD SPEED 30 km/h
-0.2
0
0.2
0.4
0.6
0.8
1
0 5 10 15 20 25 30 35 40 45 50
∆Kt*Correlation
Site-pair distance distance (km)
One minute
5-minutes
15-minutes
30-minutes
One Hour
© Richard Perez / Tom Hoff

16. SOUTH GT. PLAINS Dec 2010
CLOUD SPEED 44 km/h
-0.2
0
0.2
0.4
0.6
0.8
1
0 5 10 15 20 25 30 35 40 45 50
∆Kt*Correlation
Site-pair distance distance (km)
One minute
5-minutes
15-minutes
30-minutes
One Hour
© Richard Perez / Tom Hoff

17. -0.2
0
0.2
0.4
0.6
0.8
1
0
∆Kt*Correlation
-0.2
0 5 10 15 20 25 30 35 40 45 50
Site-pair distance distance (km)
© R. Perez & T. Hoff

18. 0
1
2
3
4
5
6
7
8
9
10
0 5 10 15
CorrelationZeroCrossoverDistance(km)
FluctuationDeltaT(minutes)
© Richard Perez / Tom Hoff
∆t
ZeroCorrellationDistance

19. BASE GENERATION
VARIABLE GENERATION
SOLAR GENERATION STORAGE
CRITICAL TIME SCALE
Seconds Minutes Half Hour Hour
Small PV
Large PV or dist. feeder
Utility
Balancing Area
Application
Technical
Solutions
Interconnection Hardware
Voltage reg. devices
Storage
Load Management, contingency variable generation
SolarAnywhere
High Resolution
SolarAnywhere
Standard Resolution
© R. Perez & T. Hoff

20. CRITICAL TIME SCALE
Seconds Minutes Half Hour Hour
SolarAnywhere
High Resolution
SolarAnywhere
Standard Resolution
© R. Perez & T. Hoff
Measured and simulated
10 second fleet output
for a 4 km x 4 km region

21. © R. Perez & T. Hoff.
© Richard Perez / Tom Hoff

22. -1
-0.5
0
0.5
1
DeltaKt*
-1
-0.5
0
0.5
1
DeltaKt*
-1
-0.5
0
0.5
1
DeltaKt*
single point
-1
-0.5
0
0.5
1
DeltaKt*
single point
20-Second
fluctuations
1-minute
fluctuations
5-minute
fluctuations
15-minute
fluctuations
SINGLE
POINT
© Richard Perez / Tom Hoff

23. -1
-0.5
0
0.5
1
DeltaKt*
-1
-0.5
0
0.5
1
DeltaKt*
-1
-0.5
0
0.5
1
DeltaKt*
-1
-0.5
0
0.5
1
DeltaKt*
20-Second
fluctuations
1-minute
fluctuations
5-minute
fluctuations
15-minute
fluctuations
SINGLE
POINT
40x40 km
AREA
© Richard Perez / Tom Hoff

24. Hourly Variability divided by 5
3-Hour Variability divided by 5
6-Hour Variability divided by 5
0
1
2
3
4
5
6
7
8
9
10
0 5 10 15
CorrelationZeroCrossoverDistance(km)
FluctuationDeltaT(minutes)
∆t = 24 hours
Source: Marc Perez, Columbia University
∆t
ZeroCorrellationDistance

25. Perez et al., ASRC

26. 100oF
80oF
20oF
40oF
60oF
© Richard Perez, ASRC

27. Early 2012 Heat Wave
0 30 60 100
© R. Perez & T. Hoff

28. 0.10 0.23 0.28 0.33 0.38 0.43 0.48 0.53 0.58 0.63 0.68 0.73 0.78 0.83 0.88 0.93 0.98
10 x10 km 0.3% 0.2% 0.2% 0.1% 0.1% 0.2% 0.2% 0.2% 0.3% 0.2% 0.5% 0.4% 0.6% 1.7% 3.9% 11.6% 79.2%
Clearness Index
Distributed
resource
footprint
30x30 km 0.0% 0.0% 0.1% 0.1% 0.1% 0.1% 0.2% 0.3% 0.3% 0.4% 0.3% 0.4% 1.0% 1.9% 2.9% 7.5% 84.3%
70x70 km 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.6% 0.4% 0.8% 3.9% 94.4%
90x90 km 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.1% 2.0% 97.8%
110x110 km 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 2.7% 97.3%
50x50 km 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.1% 0.4% 0.2% 0.4% 1.2% 97.6%
A/C Solar Peak Shaving Guarantee increases with resource distribution
15-year Clearness Index distribution for all hours with T >88F, Central CA
Probability of having less than a 90% ideal solar resource: ZERO
10x10km30x30km50x50km70x70km90x90km110x110km
© R. Perez & T. Hoff

29. More intense cloud impact
More intense turbidity impact
FLAT PLATE vs. CONCENTRATION
Capacityfactor
© R. Perez & T. Hoff

30. Thank you

31. SPARE SLIDES THEREAFTER