Respuesta rápida
An indexed tariff in Spain passes the wholesale OMIE pool price to you (plus margin and peajes); a fixed tariff locks a stable €/kWh for 12 months. Indexed wins for households that shift load to valle hours and accept volatility; fixed wins for rigid daytime usage and predictability. Always compare the effective €/kWh (total bill / total kWh), not the advertised price.
En 30 segundos
- ✓Locate the 'Power Contracted' (Potencia) section to see if you are overpaying for capacity.
- ✓Identify the 'Cost per kWh' or 'Energy' line to find your current rate.
- ✓Check for 'Vampire Services' like hidden insurance or maintenance fees.
Stop guessing, start auditing
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Why you can trust it
- Free and no signup
- AI trained on the Spanish market (~30s)
- Privacy-first: ephemeral processing (we don't store your bills)
Transparencia y fuentes
Autoría
Equipo ahorr.ai
Auditoría energética (España)
Actualizado: 21 de abril de 2026
Metodología orientada a decisión: separar coste fijo/variable, detectar extras y comparar opciones con números claros.
Metodología
- →Separamos coste fijo (potencia/término fijo), energía y cargos/impuestos.
- →Buscamos sobrecostes típicos: potencia sobredimensionada, servicios extra, lecturas estimadas.
- →Damos pasos accionables (qué tocar primero) con ejemplos orientativos, no promesas.
- →Enlazamos fuentes oficiales y marcamos lo que puede variar por comercializadora.
Información orientativa (España). Comprueba condiciones con tu comercializadora: precios, peajes, cargos e impuestos pueden variar.
The difference between options (applied to tarifa indexada vs fija)
Understanding the core difference is the first step in your energy autopsy.
What they sell you vs what you pay
Marketing often highlights a low kWh price but hides the 'management fee' or the cost of power. In a fixed rate, you pay for stability; in an indexed rate, you pay for transparency.
The trap of comparing only kWh
Focusing only on the energy price ignores the fixed terms and 'vampire' services that can inflate a bill by 20% without you noticing.
Decision matrix (when each one suits you)
Your lifestyle dictates which tariff will actually save you money.
If you consume at peak hours
If your home is most active between 10 AM and 2 PM, a fixed rate usually protects you from the highest market prices.
- ✓Ideal for families with standard schedules
- ✓Better for those who don't want to check daily prices
- ✓Provides a 'ceiling' for your monthly expenses
If you can move consumption to off-peak
If you can program your dishwasher or charge an EV at night, the indexed rate is almost unbeatable.
- ✓Best for tech-savvy users
- ✓Significant savings during spring and autumn
- ✓Requires monitoring market trends
Risks and small print (in human)
Every contract has shadows. Here is how to shine a light on them.
Volatility
Indexed rates are tied to the wholesale market. If there is a geopolitical crisis, your bill will reflect it immediately.
Permanence and extras
Many 'cheap' fixed rates come with a 12-month commitment or mandatory maintenance services that negate any savings.
How to decide with your real consumption (without 'opinionitis')
Stop listening to neighbors and start looking at your data.
What data your bill provides
Your bill contains your hourly consumption curve. This is the 'DNA' that tells you exactly if an indexed rate would have been cheaper last month.
CTA to audit
Don't do the math manually. A forensic audit can process these thousands of data points in seconds.
Checklist: Indexed vs Fixed Decision Matrix
- ✓Locate the 'Power Contracted' (Potencia) section to see if you are overpaying for capacity.
- ✓Identify the 'Cost per kWh' or 'Energy' line to find your current rate.
- ✓Check for 'Vampire Services' like hidden insurance or maintenance fees.
- ✓Verify your peak usage vs. contracted power in the consumption graph.
- ✓Check for 'Permanence' clauses that might penalize you for switching.
Decision Matrix: Indexed vs Fixed
| Consumer Profile | Recommended Tariff | Main Advantage | Main Risk |
|---|---|---|---|
| The Optimizer (Shifts loads) | Indexed | Pays market price during low demand | Sudden market spikes |
| The Stable Budgeter | Fixed | Predictable monthly cost | Paying a premium for 'peace of mind' |
| The High-Power User | Fixed (with power optimization) | Avoids volatility on high volume | Hidden 'vampire' services in the contract |
Estimates based on standard Spanish market profiles.
The Norwegian Couple's Indexed Win in Bilbao
A Norwegian couple in a 95 m² Bilbao flat had an EV and could schedule charging after 00:00. On their previous fixed tariff, the EV doubled their effective price. Switching to an indexed tariff with nightly valle charging dropped the effective €/kWh from €0.22 to €0.13 — a €420/year saving on the same consumption.
Hallazgos
- ✓EV charging shifted entirely to P3 valle hours (post-00:00).
- ✓Effective price €0.22/kWh on fixed → €0.13/kWh on indexed.
- ✓Annual saving of ~€420 without changing total consumption.
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Preguntas frecuentes
Privacy-First Analysis
We process your data ephemerally. No spam, no commercials, just the truth about your energy costs.
Disclaimers
- Informational tool; not financial advice.
- We don’t guarantee savings: these are estimates.