A free and open source finite-difference simulation tool for solar modules

Inhomogeneities and series resistance have a pronounced impact on solar module performance. In the last few years many tools have been developed which model the impact of lateral inhomogeneities and the series resistance arising from the lateral current transport. Particularly popular are SPICE-based models, which use a SPICE circuit simulator to model the solar module (i.e. the involved differential equations are solved through an electronic network equivalent). In this paper we present our new free and open source solar module simulator. Our simulator features a variable, adaptive mesh, which allows fast and accurate simulation of large devices with small geometrical details. Furthermore, the program provides a flexible set of tools to define and simulate complex geometries. Finally, our tool does not depend on SPICE to do the simulations but has its own built-in solver. This reduces overhead as no netlist needs to be generated for SPICE, and, in addition, it allows to use numerical methods optimized for the given problem where the methods used in SPICE are intended for generic electronic circuits.