This price is calculated daily by the Spanish Electricity Grid (in Spanish, REE), based on:
The energy prices per hour on the market.
Applying the average consumer profile.
Actual daily energy market prices are used, and not a quarterly price as before.
However, it must be taken into account that the prices vary on the daily energy market, which means that with this new calculation method these variations will be reflected in a different final price on each electricity bill.