MAC protocols for multi-hop WSNs have to address the challenge of coordinating duty-cycling transmitters with duty-cycling receivers. All the suggested protocols can be classified into three basic paradigms: the synchronization, the preamble and the beaconing paradigm. In this paper, we discuss the suitability of the three paradigms in the context of Energy Harvesting — Wireless Sensor Networks (EH-WSNs) in which nodes are powered by energy that they harvest from their surrounding environment. The two suitable paradigms are modeled and compared to each other. The analysis indicates the specific conditions under which a scheme is more suitable than the other.