Online Electrochemical Impedance Spectroscopy (EIS) estimation of a solar panel

Electrochemical Impedance Spectroscopy (EIS) techniques are useful tools for being able to look at the characterisation of solar panels under different conditions and/or with different material components. However EIS analysis is mostly undertaken offline with bespoke equipment. This paper describes a method of undertaking EIS measurement on-line without the use of additional equipment by manipulating the control of the solar panel connected dc-dc power electronic converter. The power electronic control is used to inject an additional low-frequency signal into the circuit and then sweep this frequency across a range to replicate the functionality of the EIS without the need for a separate excitation circuit while maintaining full operational functionality. This paper describes the methodology and presents some experimental results compared with EIS results under the same conditions to illustrate the concept.