The values for surface solar radiation and surface solar radiation downwarsd are in J/m^2. In order to obtain the Wm^2, i have divided the values by 3600. However, the irradiance values that I am obtaining are over 7000, which is physically impossible. Is there an issue with irradiance values or the irradiance values should be obtained in some different way?
Solar radiation is an accumulated variable. Have you checked the documentation on Confluence? Conversion table for accumulated variables (total precipitation/fluxes) - Copernicus Knowledge Base - ECMWF Confluence Wiki