Sky InSight™ permits to collect ultra-local information about the clouds passing above it. An infrared camera films a hemispherical mirror, in order to observe the cloud ceiling with a 180° angle corresponding to a 2-kilometer radius. Various cloud cover parameters are then obtained by processing the sky temperature map.
Several weather sensors are also embedded into Sky Insight: a solar reference cell, a thermometer, and a humidity sensor. The compiled data contribute to the optimization of the algorithms for solar forecasting using ground images. The data acquisition and transmission system is directly integrated into Sky Insight, thereby facilitating its on-site operational deployment.
In a nutshell, the use of the infrared camera within all-sky imager offers many advantages in comparison to optical cameras:
- Overcome issues related to optical brightness and contrast variations, for a steady performance in every condition (dawn, sunset, storms…)
- Get rid of the overexposure area around the sun, also named ‘circumsolar’, and which leads to segmentation errors with standard cameras (see image opposite)
- Gather additional information on the altitude and optical thickness of the clouds, that enable to classify them based on their characteristics.