Light Intensity Modulation and Two-Port Network Analysis of Dynamic Response of Photovoltaic Module

Dynamic testing methods of photovoltaic panels are those which analyze the response of the panel at non-static operating condition. Dynamic characteristics of photovoltaic cells can reveal aging and defects within a device which may not be obvious through static forms of testing. Forms of static testing are more common, namely I-V curve testing and MPPT analysis and can provide end users with information regarding the voltage, current, and power output of a panel with respect to light conditions. However, by considering the AC impedance model of a cell/panel, more insight into panel can be obtained. This paper introduces a new method for measuring the dynamic response of a photovoltaic (PV) module using light intensity modulation. The aim of this work is to capture the frequency response of the panel using the proposed modulation technique and transmission parameter derivation. By controlling the PWM signal used in a switch-mode LED driver, a sinusoidally modulated light intensity of variable frequency is applied to a PV module. A collimating lens and a reflector are used to evenly distribute light across the panel, ensuring each cell is perturbed equally. A two-port network approach is then utilized to represent the dynamic response. Through the two-port network analysis, the ratio of LED current to PV module voltage is used to display the response from the light intensity modulator to the PV module. To validate the proposed method, a 36-cell, 10W PV panel is used. The proposed approach is validated through simulation and experimental testing using a synchronous buck converter to control the optical output of a 100W white LED array. A collimating lens and light reflector are used to optimize light spread across the panel and ensure equal illumination across each cell. The design is tested to show the dynamic response of a 10W solar panel.