Simulating irradiance enhancement dependence on cloud optical depth and solar zenith angle

•Irradiance enhancement (IE) was modeled with a radiative transfer model.•With the sun at zenith, IE increases up to cloud optical depth of 3, then decreases.•IE magnitude increases with increasing solar zenith angle (SZA).•Maximum IE magnitude found to be 1.47 times the clear sky GHI or one cloud.•Two-cloud model used to simulate IE extremes as high as 1.63.