Respuesta Rápida
Should you choose a fixed-rate export credit or an indexed tariff tracking the hourly Spanish energy spot price? Understand the differences and market dynamics. La configuración óptima depende de su consumo real, la orientación del tejado, las necesidades de batería y la elección de la tarifa de exportación adecuada.
The export tariff choice: Fixed or Indexed?
When registering your solar system for export compensation (compensación de excedentes) in Spain, you must choose between two compensation models: fixed-rate or indexed-rate.
This choice dictates how much you are paid for every kilowatt-hour of surplus energy you feed back into the grid. Making the wrong choice can drastically reduce your monthly solar return.
What is a fixed-rate export tariff?
Under a fixed export tariff, your supplier pays you a constant price for every kWh of exported energy (e.g., €0.08 or €0.10 per kWh), regardless of the time of day or current market conditions.
This model provides high predictability. You can easily estimate your monthly credit, and you are protected from wholesale market price crashes during the sunniest hours of the day.
What is an indexed-rate export tariff?
Under an indexed export tariff, the price paid for your exported solar energy varies hourly. It tracks the Spanish wholesale electricity market (OMIE) spot price, minus a small supplier margin.
During peak solar generation hours (12:00 to 15:00) when thousands of solar systems are exporting power simultaneously, the wholesale spot market price in Spain can crash to near zero (or even turn negative). If you are on an indexed tariff, you will be paid very little for your peak exports during these hours.
Which option is best for you?
For the majority of residential solar owners in Spain, a **fixed export tariff** or a **virtual battery tariff** with fixed export credits is currently the best choice.
If you have a very large system and want to automate your exports, or if you consume most of your electricity during peak hours, indexed tariffs can be evaluated, but they carry market volatility risks.
For electricity tariff switching and post-install bill optimisation, we work alongside weSwitchSpain to analyze your hourly consumption and export profiles, helping you choose the most competitive fixed vs indexed contract.
