The European energy system is undergoing, and will continue to in the future, a transition towards a more sustainable energy system. An important part of this will be the deployment of smart energy solutions in the household sector, including smart meters, controls, appliances, and their integration in home networks. This study is in support of the Commission's work related to smart energy solutions in the framework of the SET plan, in particular in understanding methods to develop indicators that can be used to measure progress under the Declaration of Intent for the Action 3.1 on Initiative for Smart solutions for energy consumers. First, 'smart energy solutions' are defined and the type of technologies that this includes are detailed. Once the scope has been established, existing indicators that are able to monitor the levels of deployment of such technologies will be reviewed. This includes indicators being proposed or used by international and Member State level energy agencies and other organisations. It is not intended that this study will comprehensively assess the actual deployment of smart energy solutions across all EU Member States. Instead, selected countries who are more advanced in the deployment of such technologies are considered in more detail. These include France, Switzerland, Ireland, UK, and Sweden. Finally, we review estimates of the potential of demand response in Europe to achieve goals related to energy efficiency, cost savings, and renewable energy penetration.