1. Solar Radiation Data
2. Solar Radiation Data Handbook For Employers For College

The updated 1991-2010 National Solar Radiation Database holds solar and meteorological data for 1,454 locations in the United States and its territories (see Figure 1.) Currently this site holds a solar research version of the NSRDB with additional solar fields (without meteorological data).

• According to the Occupational Outlook Handbook, employment of geophysicists is expected to grow more slowly than the average for all occupations through.
• Solar radiation which we receive as heat and light can be converted to useful thermal energy or for production of electricity either through solar photovoltaic route or through solar thermal route. Availability of reliable solar radiation data is vital for the success of solar energy installations in different sites of the country.

Our data is measured from approximately 5000 US ground stations andanother 3500 international stations. With few exceptions, our data hashalf the error of satellite and modeled data. This difference is enough tomake a solar plant appear profitable on paper when in fact it is not!The US daily data is collected every week from dozens of sources such as the USDA, NationalForest Service, and universities. This process takes between 40 and 50hours. After collecting the data, we convert all of the disparate formatsinto a single database with consistent units and perform multiple levels ofquality control - including custom solar envelopes for each NOAAclimate region and nearby station comparisons. Finally, we generate thecontour maps for our.We have learned after two years that it is impossible to automate this processcompletely, so weekly maintenance is required to preserve the integrity of thedata.

Data AccuracyWe recently consulted with a large, multi-national company who relied heavily onaccurate solar radiation data for their agricultural research. They proudlydescribed their real-time data feed with solar radiation data for every 5 kmblock of the US, updated every 15 minutes.

We asked how the measurements weremade. They didn’t know, but gave us the name of their supplier. We contacted thesupplier. The supplier didn’t know how the measurements were made – they simplyprovided the surface modeling and gridding. We obtained the name of theirsupplier, and so on, only to find that there was not a single measurement ofsolar radiation anywhere in the chain. All of this mission-critical informationon solar radiation was being estimated from cloud cover and humidity atairports.

Desktop software makes it easy to fit data with colorfulcontours and interpolate the surface down to very fine grids. It can give theuser a false sense of precision and makes it easy to mask the key question: Howaccurate is the data?US Solar Radiation DatasetsHistorical datasets of solar radiation are a key element in designing solarpower systems and energy efficient buildings; however finding accuratemulti-year data near the design site has always proved challenging.

There areonly 100-200 sites in the US providing research-quality observations of solarradiation, so this data is generally not available for engineering orarchitectural purposes.Typical Meteorological YearPerhaps the solar radiation dataset most widely used by US engineers andarchitects is the Typical Meteorological Year version 3 (TMY3) from the NationalRenewable Energy Laboratory (NREL). Each month in a TMY3 dataset containshistorical observations. Twelve specific months from a 10-30 year history wereselected as representative of the location and concatenated into a typicalmeteorological year. TMY3 data is intended only for relative comparisons ofdesigns at one location or estimates of long-term solar radiation at a site, notfor detailed engineering design or simulations (see).Satellite-Based ObservationsThe best known alternative to the TMY3 dataset issatellite-based observations of solar radiation. In fact, a significant portionof the NREL’s TMY3 incorporates SUNY (State University of New York) griddedsatellite data.

All satellite observations of solar radiation are modeled, sincethey must estimate ground radiation based on clouds and atmospheric conditions.The most widely used models in the US were developed. The NASA observations hadthe highest daily total error (27%), TMY3 and SUNY had similar errors (19%) andthe medium-quality ground measurements showed significantly lower errors (9%).The monthly total errors were similar for all datasets. The bias errors (rME) inthe observations of GHI are shown in Figure 6. NASA observations had the highestdaily bias error (16.7%), TMY3 and SUNY had similar daily bias (9.2% and 8.1%)and the medium-quality ground measurements showed significantly lower daily biaserror (3.1%). The monthly bias errors were similar for all datasets. The similarity oferrors between the TMY3 and SUNY datasets should not be surprising, since asignificant portion of the TMY3 data comes from the SUNY gridded data in theNational Solar Radiation Database.

Leaving out TMY3, a more comprehensivecomparison can be made between the NASA, SUNY and ground-based data. The nextcomparison used all of the data from 2002-2005 where there was overlap betweenthe SUNY gridded data in the National Solar Radiation Database and seven USCRNstations in the southern half of the US (259 location- months of data). NASAsatellite data for the locations was obtained from their POWER website. Theprovided corresponding ground-based measurements from oneor more stations at each area. All ground stations were within 20 miles and 500feet elevation of the USCRN reference stations. The same procedure was used tocalculate the total and bias errors in the various datasets. Figures 7 and 8show that daily observations from medium-quality ground stations had less thanhalf the errors of the NASA and SUNY observations.Figure 7 - Total errors in observations of globalhorizontal irradiance from various sources.Figure 8 - Bias errors in observations of globalhorizontal irradiance from various sources.

Solar Radiation Data

These results are similar toother published comparisons. Figure 9 -Total and bias errors in global horizontalirradiance observations from paired high-quality stationsSummaryVignola, et al. Suggest that there is a place for both satellite andground-based measurements in forming a comprehensive solar radiation databasefor the entire US, with satellite data providing general coverage augmented byground-based data for detailed engineering and scientific purposes.

Solar Radiation Data Handbook For Employers For College

Solar measurement for Solar Site AssessmentThe sun irradiation differs from site to site. Thus it is essential to measure the local irradiation to design profitable solar power plants. There are certain methods and technologies to measure the irradiation.