Written with people moving from Turkey in mind. The Portuguese rules still apply more broadly.
Simple vs. Bi-Hourly Electricity
When setting up electricity, you can choose between a "Simples" tariff (same price all day) or "Bi-horário" (cheaper at night and weekends, more expensive during the day). Bi-horário is ideal if you can run washing machines or heaters after 22:00.
Check your lifestyle. If you work from home and use AC during the day, the Simple tariff is likely cheaper. You can switch between these tariffs for free by contacting your provider.