Due to ongoing changes in the power grid towards decentralised and highly volatile energy production, smart electricity meters are required to provide fine-grained measurement and timely remote access to consumption and production data. This enables flexible tariffing and dynamic load optimisation. As the power grid forms part of the critical infrastructure of our society, increasing the resilience of the grid’s software components against failures and attacks is vitally important.In this paper we explore the use of Protected Module Architectures (PMAs) to securely implement and deploy software for smart electricity meters. Outlining security challenges and an architectural solution in the light of security features provided by PMAs, we evaluate a proof-of-concept implementation of a security-focused smart metering scenario. Our implementation is based on Sancus, an embedded PMA for low-power microcontrollers. The evaluation of our prototype provides strong indication for the feasibility of implementing a PMA-based high assurance smart meter with a very small software Trusted Computing Base, which would be suitable for security certification and formal verification.