Issue 12, 2021

Emerging investigator series: quantifying the impact of cloud cover on solar irradiance and environmental photodegradation

Abstract

Environmental photodegradation is dependent on the solar irradiance that reaches the Earth's surface, and photodegradation half-lives of contaminants are typically estimated assuming clear sky (i.e., cloudless) conditions. In this work, the effect of cloud cover on solar irradiance was investigated. Data from the National Renewable Energy Laboratory (NREL), which spanned 3 years of observations (10/2017 to 12/2020), were used to train two machine learning models to predict irradiance based on three inputs – day of year, time of day, and percentage of the sky that was cloudy. Results showed a non-linear relationship between cloud cover and irradiance. Solar irradiance was minimally impacted up to ≈50% cloud cover but decreased by ≈67% at 100% cloud cover. Both random forest and artificial neural network models performed well with relative root mean squared errors of 26–31%, which varied depending on the source of cloud cover data and the spectral region being modeled. Daily irradiance values for a whole year were predicted for varying cloud conditions using the machine learning models; this result was approximated using a quadratic fit of y = 1 − 0.00243x − (4.24 × 10−5)x2 where y is the fraction of clear sky irradiance expected and x is the percentage of cloud cover in the sky. In addition, the model results supported that there was no wavelength dependence for the effect of cloud cover. Therefore, decreases in both direct and indirect photodegradation rates should be proportional to the decrease in irradiance, which has a non-linear dependence on cloud cover.

Graphical abstract: Emerging investigator series: quantifying the impact of cloud cover on solar irradiance and environmental photodegradation

Supplementary files

Article information

Article type
Paper
Submitted
28 iyl 2021
Accepted
01 noy 2021
First published
09 noy 2021

Environ. Sci.: Processes Impacts, 2021,23, 1884-1892

Emerging investigator series: quantifying the impact of cloud cover on solar irradiance and environmental photodegradation

M. G. Nevins and J. N. Apell, Environ. Sci.: Processes Impacts, 2021, 23, 1884 DOI: 10.1039/D1EM00314C

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements