Report
Reference
Interannual variability and global irradiance evaluation
INEICHEN, Pierre & Solar Heating and Cooling IEA Task 36
Abstract
Ten to fourteen years ouf ground data acquired at 19 different sites are used to analyze the interannual variability of the solar irradiance and to compare it to average and/or interpolated data, software generated typical years and satellite derived data.
INEICHEN, Pierre & Solar Heating and Cooling IEA Task 36. Interannual variability and global irradiance evaluation. Geneva : Solar Heating and Cooling IEA Task 36, 2009, 15 p.
Available at:
http://archive-ouverte.unige.ch/unige:23515
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Interannual variability and global irradiance evaluation
Pierre Ineichen University of Geneva November 2009
Abstract
Ten to fourteen years ouf ground data acquired at 19 different sites are used to analyze the interannual variability of the solar irradiance and to compare it to average and/or interpolated data, software generated typical years and satellite derived data.
Knowledge Management
1. Introduction
Models converting satellite images into the different radiation components become increasingly performing and give often better estimation of the solar irradiance availability than ground measurements if the station is not situated in the near vicinity of the application.
Two different kinds of model are used to circumvent the lack of ground measurements:
«average» models based on 10 to 20 years of ground measurements and interpolation between stations, and satellite based models that give «real» time series for specific years.
The present study analyzes the interannual variability of the solar irradiance and compares it to the corresponding annual irradiance obtained from different evaluation models.
2. Ground measurements
Data from 13 European and 6 American ground stations were collected to conduct the study. The geographic locations of the stations cover latitudes from 35°N to 60°N, altitudes from sea level to 3000 m and a great variety of climates. For stations part of the SurfRad [Surfrad], BSRN [BSRN] and CIE [CIE 1994] networks, high precision instruments [WMO 2008] such as Kipp and Zonen CM10 and Eppley PSP pyranometers, are used to acquire the data. For the other stations, it was not possible to determine the exact type of instruments. A stringent calibration, characterization and quality control was applied on all the data by the person in charge of the measurements (following IDMP recommendations [CIE 1994]), the coherence of the data was verified by the author.
The list of the stations is given on Table I.
3. Derived data
Two different derived data sets are analyzed. The first set of data are «average» data, obtained from 10 to 20 years of measurements, and partially interpolated between stations. Some of them are corrected with the help of satellite images. These are derived within the following networks, programs or software:
- PVGIS: Photovoltaic Geographical Information System provides a map-based inventory of solar energy resource and assessment of the electricity generation from photovoltaic systems in Europe, Africa, and South-West Asia (available from http://re.jrc.ec.europa.eu/pvgis/index.htm).
- WRDC: the World Radiation Data Centre Online Archive contains international solar radiation data stored at the WRDC, which is a central depository for data collected at over one thousand measurement sites throughout the world (available from http://wrdc-mgo.nrel.gov/).
- RetScreen: The RETScreen Clean Energy Project Analysis Software is a unique decision support tool developed with the contribution of numerous experts from government, industry, and academia. The software, provided free-of-charge, can be used worldwide to evaluate the energy production and savings, costs, emission reductions, financial viability and risk for various types of Renewable-energy and Energy-efficient Technologies (RETs).(available from http://www.retscreen.net).
- NASA SSE is a renewable energy resource web site of global meteorology and surface solar energy climatology from NASA satellite data on 1 by 1 degree resolution (available from http://eosweb.larc.nasa.gov/sse/).
- EMPClimate: this database contains monthly means of solar irradiance (downwelling shortwave irradiance), minima, maxima and mean values of air temperature at 2 m, minima, maxima and mean values of relative humidity at 2 m and covers the whole world. It has been created by data fusion techniques applied to satellite data, meteorological re-analyses from the National Centers for Environmental Prediction and the National Center for Atmospheric Research (NCEP /NCAR USA) and orography for the period 1990-2004 by Mines ParisTech (available from the MESOR1 portal at http://www.mesor.org).
- Meteonorm is a comprehensive meteorological reference software, incorporating a catalogue of meteorological data and calculation procedures for solar applications and system design at any desired location in the world. It is based on over 23 years of experience in the development of meteorological databases for energy applications (see http://www.meteonorm.com).
- EMPA DRY and NASA TMY: Design Reference Year and Typical Reference Year contain hourly climate data for a specific location, arranged as hourly sets of simultaneous climate parameters. The basic requirement for a DRY or a TRY are that it correspond to an average year, both regarding monthly or seasonal mean values, occurrence and persistence of warm, cold, sunny or overcast periods.
- ESRA: the European Solar Radiation Atlas is oriented towards the needs of the users like solar architects and engineers, respecting the state of the art of their working field and their need of precise input data. From best available measured solar data complemented with other meteorological data necessary for solar engineering, digital maps for the European continents are produced. Satellite-derived maps help in improving accuracy in spatial interpolation (see http://
www.helioclim.com). TRY are included.
- Satel-Light is a Meteosat image based data server developed within a Joule XII European project that provides 5 years of half hourly data of solar irradiance and
1) MESOR: Management and Exploitation of Solar Resource Knowledge. The MESoR project is a European funded Coordination Action which aims at removing the uncertainty and improving the management of the solar energy resource knowledge. The project includes activities in user guidance (benchmarking of models and data sets;development of a handbook on best practices on how to use solar resource data), unification of access to information (use of advanced information technologies; offering one-stop-access to several databases), connecting to other initiatives (INSPIRE of the EU, POWER of the NASA, SHC and PVPS of the IEA, GMES/GEO) and to related scientific communities (energy, meteorology, geography, medicine, ecology), and dissemination (stakeholders involvement, future R&D, communication).
daylight components with a spatial resolution of 10km by 10km. It covers all Europe and part of North Africa (available from http://www.satel-light.com).
The second set of data is obtained from satellite images, and is representative of «real»
data for specific years:
- Helioclim is part of the Soda project. It is an integration of information sources of different natures within a smart network. These sources include databases containing solar radiation parameters and other relevant information (meteorology, geography, terrain elevation, satellite-borne sensor parameters). Several of these databases, especially the solar radiation data, originate from an advanced processing of remote sensing images. At the time, three version of helioclim are available on the Soda project server, HC-1 covering the whole world on a monthly basis and HC-2 and HC-3 covering Europe on an hourly basis. The year 2005 is available for free (http:/
/www.soda-is.com and http://www.mesor.org).
- Solemi: Solar Energy Mining is a service providing irradiance data derived from Meteosat satellite images by the Deutsches Zentrum für Luft- und Raumfahrt - German Aerospace Center (DLR). Global horizontal and direct at normal irradiance are available from 1991 to 2005 for Europe and Africa, and from 1999 to 2006 for Asia. The temporal resolution is one hour and the spatial resolution about 2.5 km at sub-satellite. The free sample (available from http://www.mesor.org) is limited spatially to Europe and to the year 2005.
- EnMetSol: the database provided by the University of Oldenburg covers Europe from 1995 onwards. Data for Africa and Asia are processed on request. Global and direct irradiance values are derived from Meteosat data with full spatial resolution of the Meteosat images, corresponding to 2.5 km x 2.5 km at the sub satellite point for Meteosat First Generation (MFG, 1995-2004), and to 1 km x 1 km at the sub satellite point for Meteosat Second Generation (MSG, from 2005 onwards). Time series are delivered optionally with hourly or 30 minutes resolution for MFG, and 15 minutes resolution for MSG. The data is available on request. In addition, validation studies for the required regions are offered, if ground data is available.
- State University of New York at Albany (SUNY)
These two different categories of products will be compared separately against corresponding ground data sets.
4. «Average» year evaluation
A reference period is used for the evaluation of the first category of data sets, i.e
«average» or representative year. This period covers data from 1999 to 2006, sequence where data are available for all the considered stations. The yearly total is determined by the average over the reference period, a root mean square deviation from the average or standard deviation is also evaluated. The different products are then compared to the average over the reference period, and its root mean square deviation. For Meteonorm,
three different possibilities are investigated: monthly values obtained from the MeSor portal (http://www.mesor.org), product based on average ground data from 1983 to 1992, and on 1981 to 2000 average. The results are illustrated on Figure 1 for the station of Zürich, data acquired by the Swiss meteorological institute. The relative deviations of the measured yearly total with respect to the 1999-2006 average are represented by the blue bars. On the right of the graph, the deviation of the average over the whole period is represented in grey. The yellow bars represent the relative deviation of the different products. The root mean square deviation derived from the reference period is also given, here ±4.7%. It can be seen for this station that except for RetScreen, NASA-SSE and EMPClimate (which is a prototype), the different products give values within one standard deviation of the considered reference period. The evaluated products can therefore be used with a good precision for photovoltaic powerplant sizing (only the annual total is required in that case).
On Figure 2, the seasonal evolution of the monthly global irradiance obtained from the different products is represented for the station of Payerne, data from the BSRN network.
The interesting point is that in most of the cases, when a model over- or underestimates the irradiance, it does it over the whole year, i.e. the bias is not linked to a seasonal effect as for example the albedo variation. The results are given in Table IIa and IIb, where the deviation from the average over the reference period is given in absolute and relative values. In the «average» column, the standard deviation over the reference period is given. The two stations in grey in Table IIaare excluded from the bottom average line, due to partial snow cover in winter that affects the surface albedo. This effect is not taken into account in the models.
5. Evaluation based on a «real» year
The second set of evaluated data is compared to the a specific year, 2005 for the European sites. The Figure 3 illustrates the results for data acquired in Vaulx-en-Velin within the CIE IDMP network in a similar form than on Figure 1, but with respect to 2005 instead of the reference period. It has to be noted that the Satel-Light product should be in this category, but as its period covers only 1996 to 2000, which is not the same period than all the other models, the comparison was done with the averaged value over the 5 years.
For Vaulx-en-Velin, except for Helioclim 1 which is known to underestimate, the models are within± one standard deviation (calculated over the reference period).
The same observation as illustrated on Figure 2 for the first category can be made, no specific seasonal effect occur for any of the products. Table III gives the results for the second category of evaluated irradiance data for the European stations. Here again, the two sites with high altitude and snow coverage in winter are not included in the bottom line.
Only the data derived by SUNY are evaluated for the American sites. As the same period than for the ground measurements is available, the interannual variability analysis is done year by year and described in the following section.
6. Year by year comparison on American sites
For the six American sites, data for 10 to 14 years sequences are available, including satellite product derived by SUNYA. To remain coherent with the previous evaluation for the European sites, a reference period is defined for the same years: 1999 to 2006. The
«average» products are compared to this reference period, and the «real» satellite product is compared year by year for the whole acquisition period.
The results for Goodwin Creek (MI) are illustrated on Figure 4. As for the previous comparison, the measurements are represented by blue bars, the green bar for the 1999-2006 average and the grey bars for the average over whole period. The derived data are represented by the yellow bars, their average over the reference period in orange. All the annual values are normalized to the ground measurements average calculated over the reference period.
Two conclusions can be drawn from this graph:
- the majority of the «average» products remain within one standard deviation for this station and for the reference period,
- even if the derived data present a bias, except for the 1995-1997 period, it has always the same tendency, and the derived data interannual variation follows satisfactorily the ground measurements variations. The three first years have to be considered separately, the deriving algorithm has changed in 1998. This can be seen on Figure 5 for the same site, where the 12 monthly averages are plotted separately for each year, derived data against ground measurements. Two linear best fits are also represented for the data before and after 1998. A higher dispersion and a different bias can clearly be seen on the figure for the first three years. The same behavior occurs for the other American sites. The change of algorithm in 1998 is even more visible at the site of Table Mountain, where the new algorithm gives much better results as shown on Figure 6.
The annual total irradiance, the bias year by year, the 1999-2006 average and the average over the whole period are given on Table IV for all the American stations. The table confirms the bias high variability for the period before 1998, and its stabilization after 1998.
7. Conclusions
10 to 14 years ouf ground data acquired at 19 different sites are used to analyze the interannual variability of the solar irradiance and to compare it to average and/or interpolated data, software generated typical years and satellite derived data.
The main results is that the majority of the tested state of the art products gives yearly values within the natural interannual variability of the solar irradiance. When dealing with specific year and «real» satellite derived data, their interannual variability follows satisfactory the ground measurements, especially with the newset algorithms.
References
BSRN. Baseline surface radiation network.
Available from: <http://bsrn.ethz.ch/>.
CIE (1994). Guide to Recommended Practice of Daylight Measurements. CIE 108, ISBN: 3 900 734 50x.
Meteonorm 6.1, 2009. Global Meteorological Database for Engineers, Planners and Education, <http://www.meteotest.com>
MESOR 2009. Management and exploitation of solar resource knowledge. Hoyer-Klick C. et al. Solar Paces 2009 Conference proceedings, Berlin, Germany, 2009.
SURFRAD Network––Monitoring Surface Radiation in the Continental United States.
NOAA, Surface Radiation Research Branch.
Available from <http://www.srrb.noaa.gov/surfrad/index.html>.
WMO (2008). Guide to meteorological instruments and methods of observation see <http://www.wmo.int/e-catalog/detail_fr.php?PUB_ID=509&SORT=N&q=>
Figure 1 Blue bars: relative deviation of the measured yearly total from the 1999-2006 ave- rage. In grey: the deviation of the total period average . In yellow: the relative deviation of the different products from the reference period. The root mean square deviation derived from the referenc period is given in light red, here ± 4.7%.
Figure 2 Seasonal evolution of the monthly global irradiance.
Figure 3 Blue bars: relative deviation of the measured yearly total from 2005 total. In grey: the deviation of the total period average . In yellow: the relative deviation of the different products from the reference year 2005 and in orange, the deviation of the reference period from 2005.
Figure 4 Total annual irradiance normalized to the annual value of the reference period. The measurements are represented by blue bars, the green bar for the 1999-2006 average and the grey bar for the average over whole period. The derived data are represented by the yellow bars, the reference average in orange.
Figure 5 Derived monthly global irradiance versus the corresponding measurements, year by year for the station of Goodwin Creek. A best fit is represented for two separate period: before and after 1998.
Figure 6 Derived monthly global irradiance versus the corresponding measurements, year by year for the station of Table Mountain. A best fit is represented for two separate period: before and after 1998.
Table I List of the stations.
European sites climate period latitude ° longitude ° altitude m
Carpentras (F) mediterranean 1990-2006 44.08 5.06 100 BSRN - Météo France
Davos Dorf (CH) semi-continental alpin 1990-2008 46.81 9.84 1610 WRDC - Met Office
El Saler (Spain) semi arid 1999-2006 39.35 -0.32 10 FluxNet
Geneva (CH) semi-continental 1990-2009 46.20 6.13 420 CIE - UNIGE
Nantes (F) oceanic 1995-2007 47.15 -1.33 30 CIE - CSTB
Payerne (CH) moderate maritime/continental 1993-2006 46.82 6.95 490 BSRN - Météo Suisse
Sion (CH) dry alpine 1990-2008 46.22 7.33 489 ANETZ - Météo Suisse
Sonnblick (A) temperate alpine 1994-2007 47.05 12.95 3105 WRDC - ZAMG
Thessaloniki (GR) mediterranean temperate 1993-2006 40.63 22.97 60 WRDC - Met Office
Toravere (Estonia) cold humid 1999-2008 58.27 26.47 70 BSRN - EMHI
Vaulx-en-Velin (F) semi-continental 1994-2007 45.78 4.93 170 CIE - ENTPE
Wien / Hohe Warte (A) continental 1994-2007 48.25 16.35 203 WRDC - ZAMG
Zürich (CH) temperate atlantic 1990-2008 47.38 8.57 558 ANETZ - Météo Suisse
ANETZ Automatisches meteorologisches Mess-und Beobachtungsnetz
BSRN Baseline Surface Radiation Network
CIE Commission Internationale pour l'Eclairage CSTB Centre Scientifique et Technique du Bâtiment
DWD Deutscher Wetterdienst
EMHI The Estonian Meteorological and Hydrological Institute
ENTPE Ecole Nationale des Mines de Paris
UNIGE University of Geneva
WRDC World Radiation Data Center
ZAMG Zentralanstalt für Meteorologie und Geophysik/Geodynamik
United States sites climate latitude ° longitude ° altitude m
Bondville (IL) 1995-2008 40.05 -88.37 213 SurfRad - NREL
Desert Rock (NV) desert 1999-2008 36.62 -116.02 1007 SurfRad - NREL
Fort Peck (MO) 1995-2008 48.31 -105.10 634 SurfRad - NREL
Goodwin Creek (MI) 1995-2008 34.25 -89.87 98 SurfRad - NREL
Penn State (PY) 1999-2008 40.72 -77.93 376 SurfRad - NREL
Table Mountain (CO) semi-arid 1996-2008 40.13 -105.24 1689 SurfRad - NREL
NREL National Renewable Energy Laboratory
SurfRad Surface Radiation Network
operated by
operated by
Table IIa Products comparison and annual variability for the European stations. In the average column, the standard deviation calculated on the reference period is given in abolute an relative values. For the products, the deviation from the average is given.
average(99-06) PVGIS(81-90) WRDC(81-93) RetScreen(61-90) NASA-SSE(83-93) EMPClimate(Mesor) MN6(Mesor) MN6(83-92) MN6(81-00) EMPA(DRY) ESRA(81-90) Satellight(96-00)
Carpentras BSRN Year total [kWh/m2] 1581 Year total 1492 1511 1348 1491 1352 1520 1504 1522 1501 1599
fluctuation [kWh/m2] 37 -89 -70 -232 -90 -228 -61 -77 -59 -80 18
fluctuation [%] 2% -6% -4% -15% -6% -14% -4% -5% -4% -5% 1%
Davos WRDC Year total [kWh/m2] 1344 Year total 1296 1334 1371 1274 1022 1478 1405 1405 1339 1343 1117
fluctuation [kWh/m2] 43 -48 -10 27 -70 -322 134 61 61 -5 -1 -228
fluctuation [%] 3% -4% -1% 2% -5% -24% 10% 5% 5% 0% 0% -17%
Geneva CIE Year total [kWh/m2] 1258 Year total 1215 1201 1283 1283 1057 1211 1209 1208 1207 1211 1277
fluctuation [kWh/m2] 51 -43 -57 25 25 -201 -47 -49 -50 -51 -48 19
fluctuation [%] 4% -3% -5% 2% 2% -16% -4% -4% -4% -4% -4% 1%
Nantes CIE Year total [kWh/m2] 1252 Year total 1231 1200 1223 1181 1111 1226 1219 1226 1256 1231
fluctuation [kWh/m2] 47 -21 -52 -29 -71 -141 -26 -33 -26 4 -21
fluctuation [%] 4% -2% -4% -2% -6% -11% -2% -3% -2% 0% -2%
Payerne BSRN Year total [kWh/m2] 1266 Year total 1141 1170 1245 1283 978 1167 1173 1159 1172 1172 1242
fluctuation [kWh/m2] 54 -125 -96 -21 17 -288 -99 -93 -107 -95 -94 -25
fluctuation [%] 4% -10% -8% -2% 1% -23% -8% -7% -8% -7% -7% -2%
Sion ISM Year total [kWh/m2] 1355 Year total 1371 1283 1283 1052 1287 1395 1395 1314 1298 1401
fluctuation [kWh/m2] 45 16 -71 -71 -303 -67 40 40 -40 -57 46
fluctuation [%] 3% 1% -5% -5% -22% -5% 3% 3% -3% -4% 3%
Sonnblick WRDC Year total [kWh/m2] 1484 Year total 1300 1373 1390 1057 1211 1381 1410 1412 1196
fluctuation [kWh/m2] 47 -184 -110 -94 -426 -273 -102 -74 -72 -288
fluctuation [%] 3% -12% -7% -6% -29% -18% -7% -5% -5% -19%
Thessaloniki WRDC Year total [kWh/m2] 1580 Year total 1436 1117 1476 1476 1309 1523 1209 1493 1447 1521
fluctuation [kWh/m2] 40 -145 -463 -105 -105 -271 -57 -371 -87 -133 -59
fluctuation [%] 3% -9% -29% -7% -7% -17% -4% -23% -5% -8% -4%
Toravere BSRN Year total [kWh/m2] 997 Year total 964 1011 1011 864 968 969 964
fluctuation [kWh/m2] 59 -33 14 14 -133 -29 -28 -33
fluctuation [%] 6% -3% 1% 1% -13% -3% -3% -3%
Valencia FluxNet Year total [kWh/m2] 1652 Year total 1525 1724 1549 1820 1575 1677 1615 1616 1730 1669
fluctuation [kWh/m2] 38 -127 72 -103 168 -78 24 -37 -36 78 17
fluctuation [%] 2% -8% 4% -6% 10% -5% 1% -2% -2% 5% 1%
Vaulx-en-Velin CIE Year total [kWh/m2] 1401 Year total 1262 1202 1252 1265 1119 1207 1221 1275 1308
fluctuation [kWh/m2] 61 -139 -199 -149 -137 -283 -194 -180 -126 -93
fluctuation [%] 4% -10% -14% -11% -10% -20% -14% -13% -9% -7%
Wien WRDC Year total [kWh/m2] 1215 Year total 1143 1095 1105 1165 886 1108 1105 981 1093 1155
fluctuation [kWh/m2] 69 -72 -120 -111 -50 -329 -107 -110 -235 -122 -60
fluctuation [%] 6% -6% -10% -9% -4% -27% -9% -9% -19% -10% -5%
Zürich ISM Year total [kWh/m2] 1119 Year total 1096 1096 1231 1231 951 1112 1088 1094 1088 1106 1133
fluctuation [kWh/m2] 53 -23 -23 112 112 -168 -7 -31 -25 -31 -13 14
fluctuation [%] 5% -2% -2% 10% 10% -15% -1% -3% -2% -3% -1% 1%
Average Year total [kWh/m2] 1334 Year total 1261 1258 1273 1317 1114 1273 1249 1262 1195 1309 1354 all stations except fluctuation [kWh/m2] 50 -73 -112 -61 -17 -220 -61 -79 -72 -54 -59 -14
Davos & Sonnblick fluctuation [%] 4% -6% -9% -5% -1% -20% -5% -6% -6% -5% -5% -1%
Deviation from average
Deviation from average
Deviation from average
Deviation from average
Deviation from average
Deviation from average
Deviation from average
Deviation from average
Deviation from average
Deviation from average
Deviation from average
Deviation from average
Deviation from average
Deviation from average
average data
Table IIb Products comparison and annual variability for the American stations. In the average column, the standard deviation calculated on the reference period is given in abolute an relative values. For the products, the deviation from the average is given.
average(99-06) WRDC(81-93) RetScreen(61-90) NASA-SSE(83-93) EMPClimate(Mesor) MN6(Mesor) MN6(81-00) NREL(TMY3)
Year total [kWh/m2] 1493 1445 1468 1417 1646 1494 1462 1362
fluctuation [kWh/m2] 53 -47 -25 -76 154 2 -31 -130
fluctuation [%] 4% -3% -2% -5% 10% 0% -2% -9%
Year total [kWh/m2] 2082 2003 1973 1863 2127 2098 2077 2020
fluctuation [kWh/m2] 32 -79 -109 -219 45 16 -5 -62
fluctuation [%] 2% -4% -5% -11% 2% 1% 0% -3%
Year total [kWh/m2] 1420 1527 1402 1379 1330 1438 1418 1328
fluctuation [kWh/m2] 39 107 -17 -41 -89 18 -2 -92
fluctuation [%] 3% 8% -1% -3% -6% 1% 0% -6%
Year total [kWh/m2] 1618 1528 1580 1566 1758 1658 1582 1592
fluctuation [kWh/m2] 54 -90 -38 -52 140 40 -36 -26
fluctuation [%] 3% -6% -2% -3% 9% 2% -2% -2%
Year total [kWh/m2] 1367 1180 1333 1351 1600 1503 1503 1341
fluctuation [kWh/m2] 52 -187 -35 -17 232 135 136 -27
fluctuation [%] 4% -14% -3% -1% 17% 10% 10% -2%
Year total [kWh/m2] 1663 1590 1672 1634 1886 1669 1668 1655
fluctuation [kWh/m2] 30 -73 8 -29 223 6 5 -9
fluctuation [%] 2% -4% 1% -2% 13% 0% 0% -1%
Average Year total [kWh/m2] 1607 1546 1571 1535 1725 1643 1618 1550
all stations fluctuation [kWh/m2] 43 -62 -36 -72 117 36 11 -58
fluctuation [%] 3% -4% -2% -5% 7% 2% 1% -4%
Deviation from average Penn State PA
(surfrad) Deviation
from average Table Mountain CO
(surfrad) Deviation
from average Fort Peck MO
(surfrad) Deviation
from average Goodwin Creek MI
(surfrad) Deviation
from average Bondville IL (surfrad)
Deviation from average Desert Rock NV
(surfrad) Deviation
from average
average data
Table III Products comparison against the year 2005. The annual average is given in absolute values, the deviation from 2005 in absolute and relative values.
2005 Helioclim12005 Helioclim22005 Helioclim32005 Solemi2005 EnMetSol2005
Carpentras BSRN Year total [kWh/m2] 1596 Year total 1484 1680 1661 1686 1596
fluctuation [kWh/m2] -111 85 66 91 0
fluctuation [%] -7% 5% 4% 6% 0%
Davos WRDC Year total [kWh/m2] 1338 Year total 1030 1385 1358 1335 1375
fluctuation [kWh/m2] -308 47 20 -3 37
fluctuation [%] -23% 3% 1% 0% 3%
Geneva CIE Year total [kWh/m2] 1305 Year total 1030 1385 1358 1335 1375
fluctuation [kWh/m2] -275 80 53 30 70
fluctuation [%] -21% 6% 4% 2% 5%
Nantes CIE Year total [kWh/m2] 1302 Year total 1057 1337 1339 1335 1280
fluctuation [kWh/m2] -246 35 36 33 -22
fluctuation [%] -19% 3% 3% 3% -2%
Payerne BSRN Year total [kWh/m2] 1294 Year total 978 1254 1241 1305 1348
fluctuation [kWh/m2] -316 -40 -53 11 53
fluctuation [%] -24% -3% -4% 1% 4%
Sion ISM Year total [kWh/m2] 1385 Year total 1350 1482 1664 1412
fluctuation [kWh/m2] -35 97 278 27
fluctuation [%] -3% 7% 20% 2%
Sonnblick WRDC Year total [kWh/m2] 1488 Year total 1295 1303 1411 1041 1241
fluctuation [kWh/m2] -193 -185 -77 -447 -246
fluctuation [%] -13% -12% -5% -30% -17%
Thessaloniki WRDC Year total [kWh/m2] 1613 Year total 1245 1543 1545 1661 1574
fluctuation [kWh/m2] -368 -70 -68 48 -39
fluctuation [%] -23% -4% -4% 3% -2%
Toravere BSRN Year total [kWh/m2] 1020 Year total 1086 1015 978 995
fluctuation [kWh/m2] 66 -5 -42 -25
fluctuation [%] 6% 0% -4% -2%
Valencia FluxNet Year total [kWh/m2] 1680 Year total 1551 1786 1821 1826 1788
fluctuation [kWh/m2] -129 106 141 146 109
fluctuation [%] -8% 6% 8% 9% 6%
Vaulx-en-Velin CIE Year total [kWh/m2] 1354 Year total 1104 1395 1339 1375 1353
fluctuation [kWh/m2] -250 40 -16 21 -2
fluctuation [%] -18% 3% -1% 2% 0%
Wien WRDC Year total [kWh/m2] 1160 Year total 900 1193 1164 1196 1231
fluctuation [kWh/m2] -261 33 4 35 70
fluctuation [%] -22% 3% 0% 3% 6%
Zürich ISM Year total [kWh/m2] 1124 Year total 936 1199 1238 1203
fluctuation [kWh/m2] -188 75 114 79
fluctuation [%] -17% 7% 10% 7%
Average Year total [kWh/m2] 1349 Year total 1164 1395 1399 1392 1393
all stations except fluctuation [kWh/m2] -185 46 50 43 45
Davos & Sonnblick fluctuation [%] -16% 3% 4% 3% 3%
Deviation from 2005 Deviation from 2005
Deviation from 2005 Deviation from 2005
Deviation from 2005 Deviation from 2005
Deviation from 2005 Deviation from 2005
Deviation from 2005 Deviation from 2005
Deviation from 2005 Deviation from 2005 Deviation from 2005
Deviation from 2005
real time data
average(99-06) 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 average Year total [kWh/m2] 1493 1437 1412 1384 1369 1533 1450 1500 1489 1488 1481 1552 1447 1506 1460 1465
3 -26 -200 -79 65 -21 -24 1 12 10 5 4 32 21 13 -13
0% -2% -14% -6% 5% -1% -2% 0% 1% 1% 0% 0% 2% 1% 1% -1%
Year total [kWh/m2] 2082 2077 2049 2094 2129 2059 2114 2049 2084 2109 2135 2090
21 23 60 4 19 26 -2 32 6 12 -27 15
1% 1% 3% 0% 1% 1% 0% 2% 0% 1% -1% 1%
Year total [kWh/m2] 1420 1335 1380 1446 1364 1415 1398 1503 1418 1386 1399 1416 1421 1432 1413 1409
20 30 -2 -164 93 3 30 -25 2 40 42 45 23 7 -23 7
1% 2% 0% -11% 7% 0% 2% -2% 0% 3% 3% 3% 2% 0% -2% 1%
Year total [kWh/m2] 1618 1596 1559 1518 1535 1683 1631 1604 1549 1583 1565 1650 1681 1641 1645 1603
32 -185 -46 74 39 7 42 38 50 0 53 22 44 61 12 15
2% -12% -3% 5% 3% 0% 3% 2% 3% 0% 3% 1% 3% 4% 1% 1%
Year total [kWh/m2] 1367 1409 1328 1446 1390 1266 1333 1386 1383 1411 1355 1371
41 40 25 1 30 84 47 59 43 71 91 49
3% 3% 2% 0% 2% 7% 4% 4% 3% 5% 7% 4%
Year total [kWh/m2] 1663 1636 1624 1630 1660 1622 1641 1716 1650 1639 1690 1687 1675 1693 1659
45 -217 -344 78 61 65 35 22 44 53 69 15 -46 -15 -14
3% -13% -21% 5% 4% 4% 2% 1% 3% 3% 4% 1% -3% -1% -1%
Year total [kWh/m2] 1512 1456 1497 1493 1475 1540 1486 1539 1512 1475 1483 1539 1524 1533 1513 1501
26 -54 -114 -125 70 18 29 8 22 35 33 38 27 22 11 10
2% -4% -8% -8% 5% 1% 2% 1% 1% 2% 2% 2% 2% 1% 1% 1%
Average
mbd mbd
mbd
mbd Desert Rock NV
(surfrad)
Fort Peck MO (surfrad)
Goodwin Creek MI (surfrad)
Penn State PA (surfrad)
Table Mountain CO (surfrad) Bondville IL (surfrad) mbd
mbd
mbd
Table IV Annual total irradiance, bias year by year, 1999-2006 average and average over the whole period for the Amercica stations.
