Concentrating Solar Systems Radiation Resources Measurements, Data, and Uncertainty

Transcription

1 Concentrating Solar Systems Radiation Resources Measurements, Data, and Uncertainty NREL Electricity, Resources, and Buildings System Integration Center Daryl Myers Resource Information and Forecasting Group 28 February 2011 NREL is a national laboratory of the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy operated by the Alliance for Sustainable Energy, LLC

2 National Renewable Energy Laboratory DISCLAIMER This material was prepared as work sponsored by an agency of the United States government. Neither the United States government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Mention of commercially available manufacturer, firm, equipment, hardware, or software carries no implication of recommendation or endorsement. Now for a Short ride in a Fast Machine.(apologies to musician John Adams)

3 Solar Sensor APPLICATIONS BANKABLE DATA for FINANCIAL INVESTOR DECISIONS highest ACCURACY? BEST data? Minimize RISK? RESOURCE PROSPECTING (siting, land acquisition, etc.) OPERATIONAL MONITORING (TILTED, TRACKING SYSTEMS) resource variability impact SYSTEM PERFORMANCE VALIDATION (TILTED,TRACKING SYSTEMS) acceptance testing for financial backers/contractual obligations SYSTEM OPERATIONAL VALIDATION is it working? is it degrading? is maintenance due? Solar Radiation Models: Development and Validation OPERATIONAL FORCASTING: PAST -> Process -> FORECAST -> VALIDATE 5 minute > 15 minute > hourly > 3 hourly > daily > weekly?

4 Solar Resources: Components

5 National Renewable Energy Laboratory

6 National Renewable Energy Laboratory NREL SOLAR PROSPECTOR:

7 National Renewable Energy Laboratory National Solar Radiation [MODELED] Data Base

8 CORRELATION OF LONG & SHORT TERM DATA National Renewable Energy Laboratory

9 What to Measure? And How? Flat Plate Photovoltaic Flat Plate Solar Thermal Hemispherical (GHI) -Horizontal -Plane of Array (POA) Thermal Detector Silicon Detector Both? Direct Normal (DNI) Concentrating Solar Thermal Photovoltaic

10 What to Measure? And How? DATA QUALITY = COS(Z)+ GHI, DNI, Diffuse (Hz) Component balance; QA; Also Input for conversion models Data INTERVAL (spatial and temporal) NOTE: 15 MINUTES? 1 Second TIME CONSTANT ISSUES 1 Minute easy to downscale 5 Minute long term downscale 15 Minute loose transient info????? WHERE TO SITE?

11 Detectors

12 Instrumentation

13 National Renewable Energy Laboratory Pyrheliometer Design SOLAR RADIATION MEASUREMENTS AND INSTRUMENT CALIBRATION BY SOUTHERN CALIFORNIA ED ISON COMPANY FOR THE WEST SOLAR DATA NETWORK DORR KIMBALL MARCH 5, 1977

14 National Renewable Energy Laboratory Circumsolar Radiation NOT useable by concentrating systems! Lawrence Berkeley Laboratory Reduced Data Base contains about 200 megabytes of information, including detailed intensity profiles of the solar and circumsolar region, the total and spectrally divided direct normal radiation data, as well as the total hemispherical solar radiation in the horizontal plane and the plane facing the sun.

15 Calibration Traceability World Radiometric Reference (WRR, WMO/PMOD ±0.30% SI traceable)

16 PYRANOMETER (GHI, DHI) PYRHELIOMETER (DNI) 8% 1%

17 Estimated Measurement Uncertainties Radiometer Measurement Uncertainty* Pyrheliometer Direct Normal +/- 2% Pyranometer TP Pyranometer PD Global or Diffuse (0 < Z< 60 ) Global Diffuse +/- 5% +/- 8% +/- 15% *U 95 = (Random) 2 + (Bias) 2 Detectors: TP = Thermopile PD = Photo Diode (silicon; LIMITED SPECTRAL RANGE misses H20 impact )

18 National Renewable Energy Laboratory DNI measurement Performance % Differences between cavity reference & three thermopile pyrheliometers (clear sky, calibration conditions) RSR2(corrected) DNI 1 minute data %differences from REF RSR2(corrected) DNI Daily total % difference from REF Scatter from time constant differences (millisecond versus seconds)

19 National Renewable Energy Laboratory MEASUREMENTS U meas (±%) Global Direct Diffuse Uncertainty Model METSTAT SUNY Glo/Dif RMS (U mod ) 8 5 MODELS U mod (±%) Glo/Dif MBE (U bias ) 2 0 Dir RMS (U mod ) Dir MBE (U bias ) 4 1 U opt = (U 2 meas + U 2 mod + U bias2 ) 1/2 (±%) U opt (±%) Model Glo/Dif Dir METSTAT SUNY 8 15 Condition Time shifting Ground snow cover High latitude Condition U add Satellite (±%) Additional Uncertainty U add METSTAT (±%) Additional Uncertainty Short- and med-termfilling Long-term filling Cloud probability derivation Cloud probability nearby site ASOS-only U 95 = (U opt 2 + U add1 2 + U add2 2 ) 1/2 (±%)

20 Solar DATA Current Status LIMITED Measured data Instrumentation accuracy ~2%-5% Slow response (seconds) Expensive Measurement programs come and go Modeled data at different scales Effect of 1991 Mt Pinatubo (Source: NREL) NO high spatial ( ~ 5 km) or temporal (<1 hour) resolution data (Research projects < 1 year old as of 2011) Information Gaps/Needs DOE/NREL Research addressing: Sub-hourly time-synchronous database for temporal variability High time resolution (1 sec 10 sec samples) Higher spatial resolution microclimate/cloud effects; ( 5 km, 1 km,?) Lower uncertainty ground measurement (functional corrections applied) Updated solar resource products (NSRDB > in progress) Reliable solar resource forecasting (Europe, NOAA, NASA, NREL) 20

21 National Renewable Energy Laboratory Station Options

22 Station Considerations: See CSP Best Practices Handbook (Ch. 3) Location: terrain, horizon, obstructions, power, communications, access, electromagnetic interference; spatial density (# of stations) Security: anchoring, fencing (vandalism, theft, wildlife ) Power: grid; PV; Wind; UPS; battery; capacity/autonomy Grounding & Shielding: prevent ground loops, pickup, leakage Data Acquisition: logger calibration, accuracy, traceability, small signal performance, sample interval/speed, time synchronization, storage Communications: cell phone modems, site visit downloads, Wi-Fi Radiometer Calibrations: traceability, standards, stability, interval Radiometer Maintenance: alignment, cleaning, documentation Data Quality Assessment/Control; physical limits, multiple sensors, model comparisons Metadata: periodic recording & updating of records of above items See NREL CSP Best Practices Handbook (Chapter 3) National Renewable Energy Laboratory

23 SUMMARY Measured data SPARSE and EPISODIC Measurement instrumentation and operations are EXPENSIVE Instrumentation uncertainty needs improvement Station design depends on your project data needs; know your instruments! Measured-Model difference ~ 10% - 15% are typical, function of Site, INPUT data and REFERENCE DATA uncertainties Data Sources PROLIFERATING; benchmarking is a RESEARCH project!! International Energy Agency Task 36 on Solar Radiation Knowledge Management U.S. European Satellite Estimates uncertainty comparable Measurements AND Models: Similar Uncertainty Limits: 2%-5% - 10% ; HOURLY & Global Month Mean Daily Total 5%-10%- 15%;HOURLY & Direct Month Mean Daily Total Data accuracy improved by 50% with characterized radiometers! National Renewable Energy Laboratory

24 National Renewable Energy Laboratory

25 National Renewable Energy Laboratory BACKUP SLIDES: FOR FURTHER DISCUSSION

26 HAWAII: DATA FROM 17 STATIONS 12 5-SEC INTERVAL ON 19 MARCH 2010

27 Measurement Uncertainty Examples One MINUTE Angular Response Daily TOTAL