This paper presents a system stability analysis of a grid-
connected inverter from a linear system viewpoint. A
Photovoltaic (PV) inverter model is derived using a system
identification method, specifically the Hammerstein-Wiener
model. The PV inverter is supplied by a controllable DC power
supply and the inverter output is connected to a 220 V utility
grid. The input and output characteristics on the inverter
terminals are collected and the nonlinear model of the inverter is
obtained. The inverter model is decomposed into three parts
follow as nonlinear input, linear middle part and nonlinear
output. Both nonlinear parts are deemed static where the
dynamical behavior is described by the middle part. The
stability of the inverter is analyzed based on a linearized model
of the nonlinear system. Frequency response analysis is
performed for insight on the system dynamical behavio