Service-oriented applications (SOA) are a standard-based and technology independent distributed computing paradigm for discovering, binding and assembling loosely-coupled software services. Software product lines (SPL) on the other hand allow a generic architecture to be configured and deployed in different instances. Product lines facilitate systematic reuse through managing variability. Product line engineering is a more established discipline and so may have more solutions to offer SOA and SPL. Thus, in this paper, we will look the synergies accruing from this powerful combination. We will then look at how the technique can be used to evaluate the latest smart energy management innovation in delivering return on investment for utilities.