Why there is no UI based Peak and off-peak energy tracker. Just enter the timetable for you local grid or even better track it via automation all done without any yaml code or creating template senors.
How would that work for people who are charged a different tariff based on energy used rather than time?
The tools are provided to take account of all use cases (utility meters, weekly schedules, template sensors, etc…), you just have to put them together.
For your use case you could probably get away with a weekly schedule a utility meter and a simple automation. All of which can be set up from the UI.
For flat 24hours same tariff, nothing needs to change.
For variable tariff we needs UI based senor templates options.