In green cloud computing (GCC), power management provides many advantages, such as reducing costs, saving the environment and improving system efficiency. It is adopted in various facilities, like datacentres, which are backed by non-renewable energy (NRE) sources. These sources are not only costly, but also drastically impact the environment. This paper introduces a constrained-based power management algorithm, which considers four NRE and RE power supplies of the datacentres, grid, photovoltaic (PV), wind and battery, to fulfil the cumulative load power demand of submitted user requests (URs). The URs are fulfilled in the order of PV, wind and battery, and grid, respectively. The simulation is carried out by taking NRE sources, RE sources and both, and ten instances. The simulation results are compared using overall cost, UR assigned to NRE and UR assigned to RE to show the performance in three scenarios of the proposed algorithm.