Spectral irradiance, ground and crop dynamic reflectance. Key determinants in predicting photocurrent for agrovoltaic systems

Abstract

This research delves into the nuanced dynamics influencing photocurrent generated in bifacial photovoltaic modules within the framework of agrovoltaic applications. Our findings underscore the necessity of using spectral data over absolute values regards to the wavelength dependence for precise energy yield predictions. Particularly, it is demonstrated that the ground reflectance plays a pivotal role. The type of soil (compact or tilled) and crop growth cycle contribute to temporal variations, significantly affecting energy production.

In order to validate the proposed methodology for estimating photocurrent generated by APV systems based on spectral data, we conducted tests in two different irradiance conditions, deliberately chosen for their contrast: clear sky and hazy sky conditions. Experimental measurements were conducted for global, direct, and diffuse irradiance spectral components in both atmospheric scenarios. Additionally, we performed comprehensive spectral reflectance measurements for various soil types and crops throughout an entire growth cycle to depict the temporal variations in these values. It is observed an overestimation in the ratio between front and rear photocurrent generated by the bifacial PV module when the model relies on absolute values of solar irradiance and ground reflectance, compared to utilizing spectral input data. Furthermore, the analysis of absolute values fails to reveal a significant dependence on atmospheric conditions.

In summary, this research discussed the implications of spectral data, geometry and atmospheric conditions, for bifacial PV modules in agrovoltaic applications.