Estimating Solar Irradiance Using Sky Imagers

TL;DR

This paper introduces a novel framework that estimates solar irradiance from sky images captured by ground-based sky cameras, enabling improved short-term solar energy forecasting by analyzing cloud coverage and movement.

Contribution

The paper presents a new method for deriving solar irradiance estimates directly from sky images, validated against pyranometer data, enhancing short-term solar energy prediction accuracy.

Findings

Achieved better solar irradiance estimation accuracy than existing methods.

Successfully captured short-term variations in solar irradiance.

Validated model performance with co-located pyranometer data.

Abstract

Ground-based whole sky cameras are extensively used for localized monitoring of clouds nowadays. They capture hemispherical images of the sky at regular intervals using a fisheye lens. In this paper, we propose a framework for estimating solar irradiance from pictures taken by those imagers. Unlike pyranometers, such sky images contain information about cloud coverage and can be used to derive cloud movement. An accurate estimation of solar irradiance using solely those images is thus a first step towards short-term forecasting of solar energy generation based on cloud movement. We derive and validate our model using pyranometers co-located with our whole sky imagers. We achieve a better performance in estimating solar irradiance and in particular its short-term variations as compared to other related methods using ground-based observations.