Contents

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Spectral mismatch modifier based on precipitable water and

absolute (pressure corrected) airmass.

Syntax

Description

Estimates a spectral mismatch modifier M representing the effect on module short circuit current of variation in the spectral irradiance. M is estimated from absolute (pressure currected) air mass, AMa, and precipitable water, Pwat, using the following function:

$$M = c_1 + c_2 \times AMa  + c_3 \times Pwat  + c_4 \times AMa^{0.5} + c_5 \times Pwat^{0.5} + c_6 \times {\frac{AMa}{Pwat^{0.5}}}$$

Default coefficients are determined for several cell types with known quantum efficiency curves, by using the Simple Model of the Atmospheric Radiative Transfer of Sunshine (SMARTS) [1]. Using SMARTS, spectrums are simulated with all combinations of AMa and Pwat where:

From these simulated spectra, M is calculated using the known quantum efficiency curves. Multiple linear regression is then applied to fit Eq. 1 to determine the coefficients for each module.

Function pvl_FSspeccorr was developed by Mitchell Lee and Alex Panchula,
 at First Solar, 2015. Detailed description of spectral correction
 can be found in [2]

Inputs

Output

Example

Pwat = pvl_calcPwat(25,70) % compute precipitable water at STC temperature of 25C and 70% RH
AMa = 1.2:0.1:5;  % a range for absolute air mass
MxSi = pvl_FSspeccorr(Pwat, AMa, 'xSi');
MCdTe = pvl_FSspeccorr(Pwat, AMa, 'CdTe');

figure
plot(AMa,MxSi,'b.')
hold all
plot(AMa,MCdTe,'r.')
xlabel('Air mass')
ylabel('Spectral mismatch modifier')
legend('x-Si','CdTe','Location','South')
Pwat =

    3.5090

References