Although metallic nanostructures in solar cells provide versatility in designing useful plasmonic architectures, understanding is still limited on how to exploit their multi-scale contribution as tunable performance. In this article, we suggest a characteristic model that develops into a simple and robust tool for guiding optimization of plasmonic solar devices. The model is conceptually based on the breakdown of the active region into intrinsic and plasmonic sub-circuits, by which the terminal currents are directly correlated with particle geometries and local improvement. Measurements from organic cells support the validity of our theory, and a series of simulation provides further insights into the critical trade-off between voltage and current generation, finally offering a strategy for efficiency enhancement.