A COMPARISON OF DIFFERENT SOLAR RADIANCE SENSORS FOR PV APPLICATIONS Mavromatakis F., Franghiadakis Y., Chalampalakis G. and Vignola F. TEI of Crete &University of Oregon 9 th International Conference on Deregulated Electricity Market issues in South Eastern Europe Technological Educational Institute of Crete Laboratory of Energy and Photovoltaic Systems

Solar Radiation Measurements PV performance monitoring Resource assessment – Long term – Temporal – Nature (direct or diffuse) – Spectral distribution – Sunshine duration 9 th International Conference on Deregulated Electricity Market issues in South Eastern Europe Technological Educational Institute of Crete Laboratory of Energy and Photovoltaic Systems

 Pyranometer CMP11  PV modules Phaesun USP 10  Reference cell SI12TC  Data logger Campbell Sci. CR1000  Shunt resistances for current measurements  Thermocouples (TC) Sensors and Hardware 9 th International Conference on Deregulated Electricity Market issues in South Eastern Europe Technological Educational Institute of Crete Laboratory of Energy and Photovoltaic Systems

The CMP11 pyranometer Spectral range285 to 2800 nm Sensitivity7 to 14 µV/W/m² Response time< 5 s Zero offset A< 7 W/m² Zero offset B< 2 W/m² Directional error (up to 80° with 1000 W/m² beam) < 10 W/m² Temperature dependence of sensitivity (-10 ºC to +40 ºC) < 1 % 9 th International Conference on Deregulated Electricity Market issues in South Eastern Europe Technological Educational Institute of Crete Laboratory of Energy and Photovoltaic Systems Used for solar irradiance measurements

The Reference cell 1 st Voltage output proportional to solar irradiance 2 nd Voltage output linearly related to cell temperature 9 th International Conference on Deregulated Electricity Market issues in South Eastern Europe Technological Educational Institute of Crete Laboratory of Energy and Photovoltaic Systems

The Phaesun USP module 9 th International Conference on Deregulated Electricity Market issues in South Eastern Europe Technological Educational Institute of Crete Laboratory of Energy and Photovoltaic Systems Can a pv module be used as a solar sensor?

Calibrating a photovoltaic module 9 th International Conference on Deregulated Electricity Market issues in South Eastern Europe Technological Educational Institute of Crete Laboratory of Energy and Photovoltaic Systems

The Short Circuit Current of PV modules I sc (G t, T c, AM, AOI) = I STC [1+α (T c -T STC )] G t /G STC f 1 (AM) f 2 (AOI) I sc Instantaneous Short circuit current I STC Short circuit current at STC conditions α Rate of change of I STC with temperature T c Actual cell temperature T STC Reference cell temperature (25 o C) G t Global irradiance G STC Reference global irradiance (1000 W/m 2 ) 9 th International Conference on Deregulated Electricity Market issues in South Eastern Europe Technological Educational Institute of Crete Laboratory of Energy and Photovoltaic Systems

Spectral effects Spectra acquired by aLI1800 spectroradiometer at Heraklion, Crete. Typical cell spectral responses. 9 th International Conference on Deregulated Electricity Market issues in South Eastern Europe Technological Educational Institute of Crete Laboratory of Energy and Photovoltaic Systems

Spectral effects 9 th International Conference on Deregulated Electricity Market issues in South Eastern Europe Technological Educational Institute of Crete Laboratory of Energy and Photovoltaic Systems

Spectral effects 9 th International Conference on Deregulated Electricity Market issues in South Eastern Europe Technological Educational Institute of Crete Laboratory of Energy and Photovoltaic Systems

Angular effects 9 th International Conference on Deregulated Electricity Market issues in South Eastern Europe Technological Educational Institute of Crete Laboratory of Energy and Photovoltaic Systems

Data selection  Solar Irradiance, G t > 50 W/m 2  Angle of Incidence, AOI < 80 o  Air Mass, AM < 10 Typically data points available for each tilt (1 minute data) 9 th International Conference on Deregulated Electricity Market issues in South Eastern Europe Technological Educational Institute of Crete Laboratory of Energy and Photovoltaic Systems

Results Technological Educational Institute of Crete Laboratory of Energy and Photovoltaic Systems 9 th International Conference on Deregulated Electricity Market issues in South Eastern Europe

Measured vs estimated CMP11 and PV module (0 o tilt angle) Technological Educational Institute of Crete Laboratory of Energy and Photovoltaic Systems 9 th International Conference on Deregulated Electricity Market issues in South Eastern Europe

Horizontal level. CMP11 and PV module 76% of the values lie within ± HWHM (±0.02) 9 th International Conference on Deregulated Electricity Market issues in South Eastern Europe Technological Educational Institute of Crete Laboratory of Energy and Photovoltaic Systems

Measured : CMP11 and Ref cell (0 o tilt angle) 9 th International Conference on Deregulated Electricity Market issues in South Eastern Europe Technological Educational Institute of Crete Laboratory of Energy and Photovoltaic Systems

9 th International Conference on Deregulated Electricity Market issues in South Eastern Europe Technological Educational Institute of Crete Laboratory of Energy and Photovoltaic Systems FWHM :0.04 Measured : CMP11 and Ref cell (0 o tilt angle)

Measured vs estimated CMP11 and PV module cell (30 o tilt angle) 9 th International Conference on Deregulated Electricity Market issues in South Eastern Europe Technological and Educational Institute of Crete Laboratory of Energy and Photovoltaic Systems FWHM: 0.04

9 th International Conference on Deregulated Electricity Market issues in South Eastern Europe Technological and Educational Institute of Crete Laboratory of Energy and Photovoltaic Systems PV = 0.99 * CMP at 0 o tilt PV = 1.00 * CMP11 PV = 1.00 * CMP at 30 o tilt PV = 1.02 * CMP11 REF = 0.93 * CMP at 0 o tilt REF = 0.92 * CMP11

A byproduct of the data 9 th International Conference on Deregulated Electricity Market issues in South Eastern Europe Technological and Educational Institute of Crete Laboratory of Energy and Photovoltaic Systems How do the experimental data compare with those available from PV software ?

Solar Irradiation at the Horizontal Level 9 th International Conference on Deregulated Electricity Market issues in South Eastern Europe Technological Educational Institute of Crete Laboratory of Energy and Photovoltaic Systems

Solar Irradiation at the tilted plane 9 th International Conference on Deregulated Electricity Market issues in South Eastern Europe Technological Educational Institute of Crete Laboratory of Energy and Photovoltaic Systems PV Lab 30 tiltPVGIS 30RETSCREEN kWh/m^ kWh/m^ kWh/m^2

Horizontal and Tilted solar irradiation 9 th International Conference on Deregulated Electricity Market issues in South Eastern Europe Technological Educational Institute of Crete Laboratory of Energy and Photovoltaic Systems Pyranometer data at the horizontal (0 o ) and the tilted plane (30 o ) 1830 kWh/m^ kWh/m^2

To be done  Thorough study of residuals as a function of various parameters. Which affect the most?  Determine average cell temperatures at 0 o and 30 o  Determine monthly means and compare with transposition models  Correlate instantaneous cell temperatures and irradiances 9 th International Conference on Deregulated Electricity Market issues in South Eastern Europe Technological Educational Institute of Crete Laboratory of Energy and Photovoltaic Systems