1. Global solar radiation forecasting with non-lineal
statistical techniques and qualitative predictions
from Spanish National Weather Service
Presented by:
LUIS MARTÍN POMARES
ENERGY DEPARTAMENT
Renewable energy division
5rd Experts Meeting of the IEA SHC Task
“Solar Resource Knowledge Management”
&
MESoR Meeting
Wels, Austria
9 – 11 June 2008

2. OUTLOOK
1. TIME SERIES GLOBAL SOLAR
RADIATION HALF DAILY
PROPERTIES
2. CLEARNESS INDEX PREDICTIONS
3. LOST COMPONENT PREDICTIONS
4. LOST COMPONENT + QUALITATIVE
PREDICTIONS
5. CONCLUSIONS
2

3. TIME SERIES GLOBAL SOLAR
RADIATION HALF DAILY PROPERTIES
 Global solar irradiance half daily time series :
Non Stationary
Non Gaussian Data Data Preprocessing
Non Linear
 Removing stationarity from time series:
 Using clearness index.
 Using lost component variable.
 Subtracting each value mean value of 2d+1 days.
 Removing from time series anual armonic (first armonic from
fourier analysis).
 If the time series obtained is not stationary a good
way to achieve so is differencing consecutive days.
3

4. CIES2008, June 17-21,2008, Vigo (Spain)
CLEARNESS INDEX HALF DAILY
PREDICTIONS
45.0 ° N
IMPROVEMENT OVER PERSISTENCE IN TERMS OF %RMSD
 ierrormod el 
42.5 ° N
improvement = 1 − ÷
 ierror ÷
40.0 ° N
• Madrid RRN AEMet
37.5 ° N  persistence 
• Murcia RRN AEMet
MADRID RRN AEMet
35.0 ° N
15.0 ° W12
.5° W10.0° W 7.5 °
W 5.0 ° W 2.5° W 0.0 ° 2.5 ° E 5.0 ° E 7.5
° E 10.0
°E MURCIA RRN AEMet
M adrid: M ejora frente Persistencia M urcia: M ejora frente Persistencia
24 24
M S (2)-A R (1)/P ersistencia
22 N N (10)/P ersistencia 22
A N FIS (6)/P ersistencia
20 20
18 18
M ejo ra % R M SD
16 16 M S (2)-AR (1)/Persistencia
NN (10)/P ersistencia
14 14 A N FIS(6)/Persistencia
12 12
10 10
8 8
6 6
1 2 3
Horizonte Predicción (Sem idías)
4 5 6 1 2 3
4 4
Horizonte Predicción (Sem idías)
5 6

5. CIES2008, June 17-21,2008, Vigo (Spain)
CLEARNESS INDEX HALF DAILY
PREDICTIONS
RMSD FOR BEST MODEL: NN(10)
MADRID RRN AEMet MURCIA RRN AEMet
40 40
N N (1) N N (1 )
38 N N (2) 38 N N (2 )
N N (3) N N (3 )
36 N N (4) 36 N N (4 )
N N (5)
% R M S D P re d ic c ió n S e m id ia ria K t
N N (6) N N (5 )
34 34
N N (7) N N (6 )
32 N N (8) 32 N N (7 )
N N (9) N N (8 )
N N (10) N N (9 )
30 30
PER
N N (1 0 )
28 28 PE R
26 26
24 24
22 22
1 2 3 4 5 6 1 2 3 4 5 6
H orizonte Pre dic c ión (S em idía s ) H o rizo nte Pre d ic c ió n (S e m id ía s )
5

6. CIES2008, June 17-21,2008, Vigo (Spain)
CLEARNESS INDEX HALF DAILY
PREDICTIONS
1
0.9
0.8
KT Semidiario Previsto
0.7
0.6
0.5
0.4
0.3 6
5
0.2
4
0.1 3
2
0
0 0.1 0.2 0.3 0.4 0.5 0.6 1
0.7 0.8 0.9 1
KT Semidiario Observado 0
0 6 0.2 0.4 0.6
Kt Semidiario
0.8 1

7. EUROSUN2008, October 7-10, Lisbon (Portugal)
LOST COMPONENT
PREDICTIONS
6000
5000
4000
Wm-2
3000
2000
1000
0
0 100 200 300 400 500 600 700
Half Day
7
Differencing day by day

8. EUROSUN2008, October 7-10, Lisbon (Portugal)
LOST COMPONENT
PREDICTIONS
5000
4500
4000
Lost Component Wm-2
3500
3000
2500
2000
1500
1000
500
0 100 200 300 400 500 600 700
Half Day
8 Differencies

9. EUROSUN2008, October 7-10, Lisbon (Portugal)
LOST COMPONENT
PREDICTIONS
3000
2000
Diff Lost Component Wm-2
1000
0
-3
-1000 1.5
x 10
1
-2000
N u m b e r o f S am p les 0.5
-3000
0 100 200 300 400 500 600 700
Half Day 0
-4 000 -3000 9
-20 00 -1 000 0 10 00
D iff L ost C om ponent
2000 300 0 4 000

10. LOST COMPONENT PREDICTIONS
MADRID RRN AEMet MURCIA RRN AEMet
40 40
38 38
NN(1)
36 36 NN(2)
NN(3)
NN(4)
34
34 NN(5)
NN(6)
32
%RMSD
NN(7)
32 NN(8)
NN(9)
30 NN(10)
30 Persistencia
28
28
26
26 24
24 22
22 20
1 2 3 4 5 6 1 2 3 4 5 6
Prediction Horizon Half Daily Prediction Horizon Half Daily
10

11. CIES2008, June 17-21,2008, Vigo (Spain)
LOST COMPONENT
PREDICTIONS
IMPROVEMENT OVER PERSISTENCE IN TERMS OF %RMSD
0.3
0.28
MADRID RRN AEMet 0.26
M adrid: M ejora frente Persistencia
24 0.24 N N /PE R
M S (2)-A R (1)/P ersistencia
0.22
Im p ro v e m e n t % R M S E
22 N N (10)/P ersistencia
A N FIS (6)/P ersistencia
20 0.2
18 0.18
M ejo ra % R M SD
16 0.16
14 0.14
12 0.12
10 0.1
8 0.08
6
1 2 3 4 5 6
0.06
Horizonte Predicción (Sem idías) 1 2 3 4 5 6
Pre dic tion Horizon
11

12. CIES2008, June 17-21,2008, Vigo (Spain)
LOST COMPONENT
PREDICTIONS
IMPROVEMENT OVER PERSISTENCE IN TERMS OF %RMSD
0.3
MURCIA RRN AEMet 0.28
0.26
M urcia: M ejora frente Persistencia
24 0.24
Im p ro vem en t % R M SD
22 0.22
20 0.2
18 0.18
16 M S (2)-AR (1)/Persistencia 0.16
NN (10)/Persistencia
14 A NFIS (6)/Persistencia 0.14 N N /P E R
12 0.12
10 0.1
8 0.08
6
1 2 3 4 5 6 0.06
Horizonte Predicción (Sem idías) 1 2 3 4 5 6
Horizon Prediction Half D aily
12

13. EUROSUN2008, October 7-10, Lisbon (Portugal)
LOST COMPONENT
PREDICTIONS
13

14. EUROSUN2008, October 7-10, Lisbon (Portugal)
AEMet Synoptic Predictions by Site
Total Cloud Cover
ECMWF
HIRLAM/AEMet
PROMETEO
WRF/MM5…. Energy Values
14

15. EUROSUN2008, October 7-10, Lisbon (Portugal)
LOST COMPONENT + QUALITATIVE
PREDICTIONS
MADRID RRN AEMet MURCIA RRN AEMet
40 40
NN(1)
NN(2)
35 35 NN(3)
NN(4)
NN(5)
NN(6)
30 30 NN(7)
%RMSD
NN(8)
NN(9)
25 25
%RMSD
NN(10)
PER
20 20
15 15
10 10
1 2 3 4 5 6 1 2 3 4 5 6
Prediction Horizon Half Daily Prediction Horizon Half Daily
15

16. EUROSUN2008, October 7-10, Lisbon (Portugal)
LOST COMPONENT + QUALITATIVE
PREDICTIONS
MADRID RRN AEMet MURCIA RRN AEMet
0.7 0.7
NN(10)/PER
Improvement %RMSD
0.68 NN(10)/PER
Improvement %RMSD
0.68
0.66 0.66
0.64 0.64
0.62 0.62
0.6 0.6
1 2 3 4 5 6 1 2 3 4 5 6
Horizon Prediction (Half Daily) Horizon Prediction (Half Daily)
16

17. EUROSUN2008, October 7-10, Lisbon (Portugal)
LOST COMPONENT +
QUALITATIVE PREDICTIONS
17

18. EUROSUN2008, October 7-10, Lisbon (Portugal)
LOST COMPONENT + QUALITATIVE
PREDICTIONS
MADRID RRN AEMet
40 40
35 35
30 30
%RMSD
25 25
20 %RMSD 20
15 15
10 10
1 2 3 4 5 6 1 2 3 4 5 6
Prediction Horizon Half Daily Prediction Horizon Half Daily
18