The energyEnergy production of solar energySolar energy systemsResource differs fundamentally from that of conventional energy sources. Solar energySolar energy availability is highly dependent on weather conditions, making it inherently variable. Various prediction approaches have been developed to address this variability, depending on the application and timeframe. Solar irradiance nowcasting and short-term forecasting are crucial for integrating solar plants into the electricity grid. Understanding the role of clouds and aerosols in these techniques is essential for enhancing their accuracy. This chapter provides an overview of the methods used to assess solar resourcesResource and predict solar radiation and energyEnergy across different spatial and temporal scales. Special emphasis is placed on short-term forecasting using all-sky imagersAll-sky imagers (ASIs), particularly for predicting rapid fluctuations in solar irradiance caused by cloud movements. Additionally, the integration of three-dimensional (3D) cloud fields into solar forecasting is highlighted as a key factor in improving the accuracy and reliability of solar energySolar energy predictions.