Vehicle-to-grid charging (V2G), also referred to as bidirectional charging, means your car battery is not only drawing power from the grid, but might also discharge (back) into the grid. The consequences for the power system are highly consequential, but also from the user perspective: You can save a lot of money if you use your own solar power or use dynamic tariffs. Yet, commercial vendors are slow to offer optimized charging to households, let alone V2G. There are reasons for this, but we set out to show that they are not fundamentally technical. While the industry world is dragging their feet, the power and maturity of open source allowed us to put together an open stack to allow cost-optimized and automated bidirectional charging at home, with a user-friendly UX design built on top, as well. We used strong, existing tools, and added a thin application layer (a HomeAssistant plugin). This design approach should be on the table more often in the open-source community. We will explain the design of this stack, as well as the data we collected and potential monetary benefits for the user. At the moment, the stack is rolled out at the homes of other enthusiastic front-runners. This will make sure the solution becomes more mature and makes steps to scalability. As industry is also dragging their feet on supporting the OCPP protocol, we can only support one charger right now, the Wallbox Qasar, but there is no technical limit to supporting other bidirectional chargers. We are curious if others are interested to support more chargers, and make the stack even easier to install and monitor. Soon, the commercial world will roll out more bidirectional chargers and cars (we use the Nissan Leaf), as well as home energy management solutions which lock users into specific vendor relationships (where the car is just one of the managed services). It's crucial to provide an open-source alternative, to provide independence for users, and to inspire startups.