With the promise of delivering immortality, energy har-vesting and wireless energy transfer have become the next research frontier for pervasive computing and networks. The challenge still is to adapt operations along all aspects of a sensing system (sensing, computation, communication), to deal with the varied, unpredictable or possibly intermittent supply of such energy. To understand these challenges, we currently lack sufficient tools to evaluate the impact of dif-ferent energy harvesting and transfer models- which is fur-ther exacerbated due to the high cost of deploying such sys-tems at a large scale. We present a generic, TOSSIM-based simulation framework to model energy harvesting and en-ergy transfer, enabling rapid development of harvesting- and transfer-aware applications, protocols, and system software. Our evaluation shows that even an abstract simulation model can provide useful insights, such as frequent power outages and node reboots due to intermittent energy supply. Based on these insights, we further establish the utility of this frame-work by demonstrating how high level simulations can lead to a better choice of energy scheduling algorithms.