Novel fabrication techniques have enabled increasingly controlled microstructural geometries in electrochemical energy devices, including dye-sensitized solar cells. An analytical tool, based on an electrochemical analogy to thermal fin analysis, has been developed to support the design of such microstructures. An adapted version of this tool is presented for analyzing the performance of microstructural geometry in dye-sensitized solar cells. This electrochemical fin model is capable of describing experimentally observed performance gains associated with specific microstructural geometries. The assessment of structures based on nanorod and nanoparticle architectures is addressed, and insights into trade-offs between surface charge transfer reactions and diffusive transport in solid photoelectrode phases are discussed.