a comparison of different solar radiance sensors for pv applications mavromatakis f., franghiadakis...

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

9th International Conference on Deregulated Electricity Market issues in South Eastern Europe

Technological Educational Institute of CreteLaboratory of Energy and Photovoltaic Systems

Solar Radiation Measurements

• PV performance monitoring• Resource assessment– Long term – Temporal – Nature (direct or diffuse)– Spectral distribution– Sunshine duration



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



The CMP11 pyranometer

Spectral range 285 to 2800 nmSensitivity 7 to 14 µV/W/m²Response time < 5 sZero offset A < 7 W/m²Zero offset B < 2 W/m²Directional error (up to 80° with 1000 W/m² beam) < 10 W/m²Temperature dependence of sensitivity (-10 ºC to +40 ºC)

< 1 %



Used for solar irradiance measurements

The Reference cell1st Voltage output proportional to solar irradiance

2nd Voltage output linearly related to cell temperature



The Phaesun USP module



Can a pv module be used as a solar sensor?

Calibrating a photovoltaic module



The Short Circuit Current of PV modules

Isc (Gt, Tc, AM, AOI) = ISTC [1+α (Tc-TSTC)] Gt/GSTC f1(AM) f2(AOI)

• Isc Instantaneous Short circuit current• ISTC Short circuit current at STC conditions• α Rate of change of ISTC with temperature• Tc Actual cell temperature• TSTC Reference cell temperature (25o C)• Gt Global irradiance• GSTC Reference global irradiance (1000 W/m2)



Spectral effects

Spectra acquired by aLI1800 spectroradiometer at Heraklion, Crete. Typical cell spectral responses.



Spectral effects



Angular effects



Data selection

Solar Irradiance, Gt > 50 W/m2

Angle of Incidence, AOI < 80o

Air Mass, AM < 10

Typically 450000 data points available for each tilt(1 minute data)



Results



Measured vs estimatedCMP11 and PV module (0o tilt angle)



Horizontal level. CMP11 and PV module

76% of the values lie within ± HWHM (±0.02) 9th International Conference on Deregulated Electricity Market issues in South Eastern Europe


Measured : CMP11 and Ref cell (0o tilt angle)





FWHM :0.04

Measured : CMP11 and Ref cell (0o tilt angle)

Measured vs estimatedCMP11 and PV module cell (30o tilt angle)


Technological and Educational Institute of CreteLaboratory of Energy and Photovoltaic Systems

FWHM: 0.04



PV = 0.99 * CMP11 + 12 at 0o tilt PV = 1.00 * CMP11

PV = 1.00 * CMP11 + 9 at 30o tilt PV = 1.02 * CMP11

REF = 0.93 * CMP11 - 5 at 0o tilt REF = 0.92 * CMP11

A byproduct of the data



How do the experimental data compare with those available from PV software ?

Solar Irradiation at the Horizontal Level



Solar Irradiation at the tilted plane



PV Lab 30 tilt PVGIS 30 RETSCREEN 301966

kWh/m^22096

kWh/m^22110

kWh/m^2

Horizontal and Tilted solar irradiation



Pyranometer data at the horizontal (0o) and the tilted plane (30o)

1830 kWh/m^2

1970 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 0o and 30o

Determine monthly means and compare with

transposition models

Correlate instantaneous cell temperatures and

irradiances



a comparison of different solar radiance sensors for pv applications mavromatakis f., franghiadakis...

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