Programming heterogeneous multiprocessor architectures is a real challenge when facing to a huge design space. Computer-aided design and development tools try to circumvent this issue by simplifying instantiation mechanisms. However, energy consumption is not well supported in most of these tools due to the difficulty to obtain fast and accurate power estimation. To this aim, this paper proposes and validates a power model of such platforms. The methodology is based on micro-benchmarking to estimate the model parameters. The energy model mainly relies on the energy overheads induced by communications between processors in a parallel application. Power modelling and micro-benchmarks are validated using a Zynq-based heterogeneous architecture showing the accuracy of the model for several tested synthetic applications.