More than a billion people still lack access to electricity inrural regions throughout the world. Rural electrification is thepart of the Development Engineering rearch field that studies thisissue. In theory, rural electrification is achieved through energytiers, going from low to high. In practice, low tier stand-alonesystems are very difficult to upgrade to higher-tiers micro-grids.This constitutes amissing linkthat locks millions in poverty. Inthis work, modular power electronics are analyzed as the potentialsolution to thismissing link. This paper proposes a theoreticalframework to analyze modular power converters for multi-tierrural micro-grids expansion.Five different tier scenarios areextracted from the literature and used to analyze two modularpower converter topologies. The results are summarized throughthe ”expansion signature” tool which can be used as a basis forfuture analysis