Low-power wide-area networks (LPWAN) have been rapidly gaining ground in recent years, triggered by their capability to satisfy important market segments. Narrowband Internet of Things (NB-IoT) is one of the most appealing LPWAN technologies, foreseen to play an important role in the fifth generation mobile communication (5G) network. In order to guarantee a worldwide coverage to the low-cost devices distributed all over the globe, satellite connectivity is a key asset due to their large footprint on Earth, especially in remote areas where the investment towards a terrestrial infrastructure is not justified. However, such terrestrial networks aiming at deploying satellite systems either as an integrated part of it or a stand-alone solution, would require a careful and detailed analysis covering several aspects and all the layers of communication. In this paper, we demonstrate the link budgets of a satellite-based NB-IoT system under different parameters, providing some simulation results as a benchmark for further study. In addition, we analyze and discuss the impact that different power budgets would have in important features of the NB-IoT network, such as delay, capacity and device battery life.