Methanol is a crucial commodity in the chemical industry and is employed as precursor for many products. It can be used to store fluctuating renewable energy, specifically benefiting from its liquid state at ambient temperatures. As the demand for green, renewable methanol is projected to soar in the next decades, environmentally friendly and sustainable pathways for its production have to be provided. Through the combination of proton-conducting high temperature electrolysis for the provision of dry H₂ with a heterogeneously catalyzed hydrogenation of CO₂, efficient and simple power-to-methanol production processes can be established. Here, a novel power-to-methanol system model capable of real-time transient simulation is presented and viable operating windows are determined for different key operating parameters of the respective main process stages. A techno-economic assessment is carried out to determine the specific production costs of renewable methanol. Specific methanol production costs of 2419 € t⁻¹ _MeOH for small-scale applications (1.12 MW) were retrieved, which corresponds to a more than fourfold increase over the current market price of conventionally produced methanol. Increases in system scale are found to decrease the methanol production costs due to economy-of-scale effects. The sensitivity of the process economics is assessed with regards to crucial operational and capital characteristics.