In this paper we present a new approach to obtain pointwise Thévenin equivalents from electrical measurements of non-linear sources. The classical technique to obtain the Thévenin equivalent can not find equivalent circuits of nonlinear sources. Using pointwise Thévenin equivalents it is possible to obtain equivalent circuits for non-linear sources point by point of operation. We used a photovoltaic (PV) module to show how the pointwise Thévenin equivalents work and how it compares with the classical Thévenin equivalent.