Climate Forecasting Unit

WINTERSeasonal Forecasts for Global Solar PV Energy

Melanie Davis, Francisco Doblas-Reyes, Fabian Lienert

Climate Forecasting Unit

Fig. S1.4.1: Winter solar GHI availability from 1981-2011 (ERA-Interim)

m/s

Stage A: Solar GHI (Global Horizontal Irradiance) Resource Assessment Solar PV energy potential: Where is it the sunniest?

Darker red regions of this map show where global solar GHI is highest in winter, and lighter yellow regions where it is lowest. N.b. This information is based on reanalysis* data (ERA-Interim) not direct observations.

* Reanalysis information comes from an objective combination of observations and numerical models that simulate one or more aspects of the Earth system, to generate a synthesised estimate of the state of the climate system and how it changes over time.

WINTER Solar PV Forecasts(December + January + February)

Climate Forecasting Unit

Fig. S1.4.2: Winter solar GHI inter-annual variability from 1981-2011 (ERA-Interim)

m/s

Stage A: Solar GHI Resource Assessment Solar PV energy volatility: Where does the wind vary the greatest?

Darker red regions of this map show where global solar GHI varies the most from one year to the next in winter, and lighter yellow regions where it varies the least.

N.b. This information is based on reanalysis* data (ERA-Interim) not direct observations.

WINTER Solar PV Forecasts(December + January + February)

Climate Forecasting Unit

Europe

Winter solar GHI availability Winter solar GHI inter-annual variabilitym/s

Areas of interest: Whole

ContinentS.Continent

S.E.Continent/E.India

Australia/New Zealand/Papua New Guinea/Pacific Isles

S.America Africa Asia Australia

S.Continent

N.America

S.Iberian Peninsular/Mediterranean

Stage A: Solar GHI Resource Assessment Where is solar PV energy resource potential and variability highest?

By comparing both the winter global solar GHI availability and inter-annual variability, it can be seen that there are several key areas (listed above) where solar GHI is both abundant and highly variable. These regions are most vulnerable to solar GHI variability over climate timescales, and are therefore of greatest interest for seasonal forecasting in winter.

WINTER Solar PV Forecasts(December + January + February)

Climate Forecasting Unit

Fig. W2.4.1: Winter solar GHI ensemble mean correlation(ECMWF S4, 1 month forecast lead time, once a year from 1981-2010)

time

forecast + 1.0

obs. forecast - 1.0

forecast example 1

forecast - 1.0

example 2

example 3

Stage B: Solar GHI Forecast Skill Assessment1St validation of the climate forecast system:

Can the solar forecast mean tell us about the solar GHI resource variability at a specific time?

The skill of a climate forecast system, to predict global solar GHI variability in winter 1 month ahead, is partially shown in this map. Skill is assessed by comparing the mean of a winter solar GHI forecast, made every year since 1981, to the reanalysis “observations” over the same period. If they follow the same variability over time, the skill is positive. This is the case even if their magnitudes are different (see example 1 and 2).

Perfect Forecast

Same as Climatology

Worse than

Clima-tology

WINTER Solar PV Forecasts(December + January + February)

Sol

ar G

HI

Climate Forecasting Unit

Fig. W2.4.1: Winter solar GHI ensemble mean correlation

(ECMWF S4, 1 month forecast lead time, once a year from 1981-2010)

Stage B: Solar GHI Forecast Skill Assessment1St validation of the climate forecast system:

Dark red regions of the map show where the climate forecast system demonstrates the highest skill in winter seasonal forecasting, with a forecast issued 1 month in advance. White regions show where there is no available forecast skill, and blue regions where the climate forecast system performs worse than a random prediction. A skill of 1 corresponds to a climate forecast that can perfectly represent the past “observations”.

Perfect Forecast

Same as Climatology

Worse than

Clima-tology

WINTER Solar PV Forecasts(December + January + February)

Can the solar forecast mean tell us about the solar GHI resource variability at a specific time?

Climate Forecasting Unit

Fig. S2.4.2: Winter solar GHI CR probability skill score(ECMWF S4, 1 month forecast lead time, once a year from 1981-2010)

Can the solar forecast distribution tell us about the magnitude of the solar GHI resource variability and its uncertainty at specific time?

time

forecast + 1.0

obs. forecast - 1.0

forecast example 1

forecast - 1.0

example 2

example 3

Stage B: Solar GHI Forecast Skill Assessment2nd validation of the climate forecast system:

The skill of a climate forecast system, to predict global solar GHI variability in winter 1 month ahead, is fully shown in this map. Here, skill is assessed by comparing the full distribution (not just the mean value as in the previous map) of a winter solar GHI forecast, made every year since 1981, to the “observations” over the same period. If they follow the same magnitude of variability over time, the skill is positive (example 2).

Perfect Forecast

Same as Climatology

Worse than

Clima-tology

WINTER Solar PV Forecasts(December + January + February)

Sol

ar G

HI

Climate Forecasting Unit

Fig. S2.4.2: Winter solar GHI CR probability skill score(ECMWF S4, 1 month forecast lead time, once a year from 1981-2010)

Stage B: Solar GHI Forecast Skill Assessment2nd validation of the climate forecast system:

Dark red regions of the map show where the climate forecast system demonstrates the highest skill in winter seasonal forecasting, with a forecast issued 1 month in advance. White regions show where there is no available forecast skill, and blue regions where the climate forecast system performs worse than a random prediction. A skill of 1 corresponds to a climate forecast that can perfectly represent the past “observations”.

Perfect Forecast

Same as Climatology

Worse than

Clima-tology

WINTER Solar PV Forecasts(December + January + February)

Can the solar forecast distribution tell us about the magnitude of the solar GHI resources variability and its uncertainty at specific time?

Climate Forecasting Unit

EuropeAreas of interest:

N.Brasil/N.E.Coast/N.W.Coast

Indonesia/N.Philippines/S.Korea/S.Japan/Vietnam

W. Australia/S.New Zealand/Papua New Guinea/Pacific Isles

S.America Africa

Asia Australia

Caribbean/Gulf of California/C.S.W.USA/N.W.Coast Canada

N.America

N.UK/N.Sea/S.Baltic Sea and surrounding land

Winter solar GHI magnitude, and its uncertainty forecast skill

Winter solar GHI variability forecast skill

Solar GHI variability forecast skill only

Solar GHI magnitude and its uncertainty forecast skill

E.Penins-ular/E.Namibia

Stage B: Solar GHI Forecast Skill Assessment

Where is solar GHI forecast skill highest?

By comparing both the winter global solar GHI forecast skill assessments, it can be seen that there are several key areas (listed above) where solar GHI forecasts are skilful in assessing its variability, magnitude and uncertainty. These regions show the greatest potential for the use of operational winter wind forecasts, and are therefore of greatest interest to seasonal solar GHI forecasting in winter.

WINTER Solar PV Forecasts(December + January + February)

Climate Forecasting Unit

Stage B: Solar GHI Forecast Skill AssessmentMagnitude and uncertainty forecast skillVariability forecast skill

m/sm/sm/s

SPRING Wind Forecasts

These four maps compare the seasonal winter solar GHI global forecast skill maps (bottom) alongside the winter global solar GHI availability and inter-annual variability map (top). It can be seen that there are several key areas (highlighted above) where the forecast skill is high in assessing its variability, magnitude and uncertainty, and the solar GHI is both abundant and highly variable. These regions demonstrate where winter seasonal solar GHI forecasts have the greatest value and potential for operational use.

Areas of Interest:(Forecast skill)

Areas of Interest: (Resources)

Solar GHI resource inter-annual variability Solar GHI resource availabilityStage A: Solar GHI Resource Assessment

Variability forecast skillWhere is solar GHI forecast skill highest?

WINTER Solar PV Forecasts(December + January + February)

Where is solar resource potential + volatility highest?

Europe

Whole Continent

S.Continent

S.E.Continent/E.India

Australia/New Zealand/Papua New Guinea/Pacific Isles

S.America Africa Asia Australia

S.Continent

N.America

S.Iberian Peninsular/Mediterranean

EuropeN.Brasil/N.E.Coast/N.W.Coast

Indonesia/N.Philippines/S.Korea/S.Japan/Vietnam

W. Australia/S.New Zealand/Papua New Guinea/Pacific Isles

S.America Africa Asia Australia

Caribbean/Gulf of California/C.S.W.USA/N.W.Coast Canada

N.AmericaN.UK/N.Sea/S.Baltic Sea and surrounding land

E.Penins-ular/E.Namibia

Climate Forecasting Unit

%

Fig. S3.4.1: Probabilistic forecast of (future) winter 2011, solar GHI most likely tercile(ECMWF S4, 1 month forecast lead time)

Stage C: Operational Solar GHI Forecast

This operational solar forecast shows the probability of global solar GHI resource to be higher (red), lower (blue) or normal (white) over the forthcoming winter season, compared to their mean value over the past 30 years. As the forecast season is winter 2011, this is an example of solar GHI forecast information that could have been available for use within a decision making process in November 2011.

WINTER Solar PV Forecasts(December + January + February)

N.Brasil/N.E.Coast/N.W.Coast

Indonesia/N.Philippines/S.Korea/S.Japan/Vietnam

W. Australia/S.New Zealand/Papua New Guinea/Pacific Isles

S.America

Asia

Australia

Carribbean/Gulf of California/C.S.W.USA/

N.America

AfricaE.Peninsular/E.Namibia

Areas of Interest Identified:(Resources and Forecast Skill)

Climate Forecasting Unit

%

Stage C: Operational Solar GHI Forecast

The key areas of highest interest are shown, identified in the stages A and B of the forecast methodology. These regions demonstrate where winter seasonal solar GHI forecasts have the greatest value and potential for operational use. The areas that are blanked out either have lower forecast skill in winter (Stage B) and/or lower solar GHI availability and inter-annual variability (Stage A).

Fig. S3.4.1: Probabilistic forecast of (future) winter 2011, solar GHI most likely tercile(ECMWF S4, 1 month forecast lead time)

WINTER Solar PV Forecasts(December + January + February)

N.Brasil/N.E.Coast/N.W.Coast

Indonesia/N.Philippines/S.Korea/S.Japan/Vietnam

W. Australia/S.New Zealand/Papua New Guinea/Pacific Isles

S.America

Asia

Australia

Carribbean/Gulf of California/C.S.W.USA/

N.America

AfricaE.Peninsular/E.Namibia

Areas of Interest Identified:(Resources and Forecast Skill)

Climate Forecasting Unit

%

Stage C: Operational Solar GHI Forecast

This does not mean that the blanked out areas are not useful, only that the operational solar GHI forecast for these regions should be used within a decision making process with due awareness to their corresponding limitations. The primary limitations to a climate forecast are either the forecast skill and/or the low risk of variability in solar GHI for a given region. See the “caveats” webpage for further limitations.

Fig. S3.4.1: Probabilistic forecast of (future) winter 2011, solar GHI most likely tercile(ECMWF S4, 1 month forecast lead time)

WINTER Solar PV Forecasts(December + January + February)

N.Brasil/N.E.Coast/N.W.Coast

Indonesia/N.Philippines/S.Korea/S.Japan/Vietnam

W. Australia/S.New Zealand/Papua New Guinea/Pacific Isles

S.America

Asia

Australia

Carribbean/Gulf of California/C.S.W.USA/

N.America

AfricaE.Peninsular/E.Namibia

Areas of Interest Identified:(Resources and Forecast Skill)

Climate Forecasting Unit

The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under the following projects:

CLIM-RUN, www.clim-run.eu (GA n° 265192)

EUPORIAS, www.euporias.eu (GA n° 308291)

SPECS, www.specs-fp7.eu (GA n° 308378)