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4th Meeting IEA SHC Task 36 Hamburg 23-25 Oct 2007
Uncertainty for solar products assessment and benchmarking
J. Polo, L. Ramírez, L.F.Zarzalejo, L. Martín, A. NavarroCIEMAT (Energy department – Solar Platform of Almería)
4th Meeting IEA SHC Task 36 Hamburg 23-25 Oct 2007
Uncertainty parameters
1
1
( ) /100
/
n
i ii
n
ii
g y nMBE
g n
Parameters based on deviation of data values (careful with notation)
Mean Relative Error (MRE)
Mean Bias Error (MBE)
RMSE
1
( ) 100n
i i
ii
y gMREg
2
1
1
( ) /100
/
n
i ii
n
ii
g y nRMSE
g n
Parameters based on deviation of distribution functions
KSI and OVER (Integral of KS test complete and
over critical value)
KSE
RIO
( 1 2) / 2KSE KSI w OVER w
( ) / 2RIO RMSE KSE
4th Meeting IEA SHC Task 36 Hamburg 23-25 Oct 2007
Daily analysis (Uncertainty parameters)
Caceres Madrid Murcia Coruña Valencia Santander Valladolid-10
-5
0
5
10
15
20
Unc
erta
inty
par
amet
er (%
)
Statistical uncertainty parameters dor daily irradiation
MREMBERMSE
Caceres Madrid Murcia Coruña Valencia Santander Valladolid0
10
20
30
40
50
60
70
80
90
100Uncertainty parameters for daily irradiation
RMSEIKSOVERKSE-pRIO-p
( ) / 22 1000KSI OVERKSE ( ) / 2RIO RMSE KSE
4th Meeting IEA SHC Task 36 Hamburg 23-25 Oct 2007
Daily analysis (KS Test)
0 2000 4000 6000 8000 10000 120000
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.1
Rangos de rad
Dis
tanc
es b
etw
een
CD
Fs
CoruñaCaceresMadridMurciaSantanderValenciaValladolid
4th Meeting IEA SHC Task 36 Hamburg 23-25 Oct 2007
Hourly analysis (Uncertainty parameters)
Murcia Caceres Madrid Valladolid Santander Valencia Coruña-5
0
5
10
15
20
25
30
Unc
erta
inty
par
amet
er (%
)
Statistical uncertainty for hourly irradiation
MREMBERMSE
Murcia Caceres Madrid Valladolid Santander Valencia Coruña0
10
20
30
40
50
60
70
80
90
100Uncertainty parameters for hourly irradiation
RMSEIKSOVERKSE-pRIO-p
( ) / 21000 2IKS OVERKSE ( ) / 2RIO RMSE KSE
4th Meeting IEA SHC Task 36 Hamburg 23-25 Oct 2007
Hourly analysis (KS Test)
0 200 400 600 800 1000 12000
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.1
Irradiation (Wh m-2)
Dis
tanc
es b
etw
een
CD
Fs
Coruña
Caceres
Madrid
Murcia
Santander
Valencia
Valladolid
4th Meeting IEA SHC Task 36 Hamburg 23-25 Oct 2007
Towards standardization: open issues for discussion
Solar Radiation Product uncertainty: users require one number (Radiation ± U) . Candidates: RMSE, MBE, relative error… Problems with normalization.
Model assessment: we look for more information than uncertainty. strengths and shortcomings of models is also required. Candidates: K-S Test in addition to uncertainty measures MBE, RMSE, deviations at different solar elevation angles, … are useful for this purpose.
Benchmarking of models: We should know a priori the capabilities of different models and we want to compare their response under the same conditions. Candidates: RIO parameter compiles KS test and RMSE information in one single parameter.
4th Meeting IEA SHC Task 36 Hamburg 23-25 Oct 2007
Future activity
Benchmarking exercise on one selected pixel for
one year of hourly global irradiation?
Elaboration of a guide for uncertainty (MESoR)?
