When a single solar photovoltaic (PV) module is in full sunlight, then is shaded by a cloud, and is back in full sunlight in a matter of seconds, a sharp dip then increase in power output will result. However, over an entire PV plant, clouds will often uncover some modules even as they cover others, resulting in only small changes in plant power output. Thus, the power output of a PV plant is smoother than the power output of a single module. Sandia has published the Wavelet Variability Model (WVM), implemented in Matlab, to model the spatial smoothing of irradiance over a PV plant or neighborhood with distributed PV. The WVM release includes a readme file with details on use of the WVM function and examples showing the WVM function applied to simulate both central and distributed PV.