The Joint Research Centre’s Smart Grid Interoperability Laboratory is situated at two sites, Ispra (IT) and Petten (NL). It is designed to foster a common European approach to interoperable digital energy, focussing on the smart home, community and city levels. The Smart Grid Interoperability Laboratory is part of a larger activity of the JRC, the science and knowledge service of the European Commission, encompassing electric vehicles, smart grids and batteries. The activities in 2021 are highlighted in this report.