Respuesta rápida
To find your ideal contracted power in Spain, take your maximum recorded peak (visible on your distributor's portal or smart meter) and add a 0.5 kW safety buffer. For most 2.0TD households this lands between 3.45 kW and 4.6 kW. Changing power costs around €11 (one-off) and lowers the fixed term of every future bill. If your breaker (ICP) never trips, you're almost certainly oversized.
En 30 segundos
- ✓Locate the 'Potencia Contratada' section on your latest bill to see your current kW.
- ✓Identify the 'Potencia Máxima Demandada' (Maximeter) for the last 12 months in the technical details.
- ✓Check if you have different power levels for Peak (Punta) and Off-peak (Valle) periods.
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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 real problem behind calculating ideal contracted power
Most consumers believe their electricity bill is high because they 'use too much light.' In reality, the fixed term—the power you contract—often represents a massive chunk of the bill that never changes, even if you are on vacation.
What Makes You Overpay
Standard contracts often include 'vampire' services or power levels designed for old, inefficient appliances. If your breaker never trips, you are likely paying for a safety margin you don't need.
What you can actually change
You have the right to change your contracted power. You can even have different power levels for the day and night (P1 and P2) to optimize costs if you use heavy appliances like electric vehicles or storage heaters at night.
Fast Method (No Scientific Calculator Needed)
You don't need to be an engineer to find your number. The data is already in your bill; you just need to know where to look.
The data point you need
Look for the 'Potencia Máxima Demandada' section. This is the highest amount of power you actually used simultaneously in the last year. It is the 'smoking gun' of your energy consumption.
How to interpret it
If your contracted power is 5.5 kW but your maximum demand was 3.2 kW, you are wasting 2.3 kW every single month. A safe bet is to set your power at Peak Demand + 0.5 kW to avoid accidental trips.
Checklist before touching anything
Before calling your company to lower your power, run through these forensic checks to ensure you don't end up in the dark.
Risk Signals
If your ICP (breaker) trips when you use the oven and washing machine together, you are already at your limit. Lowering it further will cause constant blackouts.
How to avoid surprises
Remember that the distributor charges about €11 for any change. If you lower it too much and need to raise it back, you will pay 'derechos de extensión' which are significantly more expensive.
The Decision: Lowering Your Contracted Power
Optimizing your kW contratados is the fastest way to reduce the 'término fijo' of your bill. Once you have the data, the decision becomes a simple matter of arithmetic rather than guesswork.
- →Check your last 12 months of peak usage.
- →Add a 0.5 kW buffer for comfort.
- →Request the change via your provider's app or customer service.
- →Verify the change in your next billing cycle.
Checklist to Calculate Your Ideal Contracted Power
- ✓Locate the 'Potencia Contratada' section on your latest bill to see your current kW.
- ✓Identify the 'Potencia Máxima Demandada' (Maximeter) for the last 12 months in the technical details.
- ✓Check if you have different power levels for Peak (Punta) and Off-peak (Valle) periods.
- ✓Verify if your 'Interruptor de Control de Potencia' (ICP) ever trips (the 'leads' falling).
- ✓Compare your current kW with your highest recorded peak plus a 0.5 kW safety margin.
- ✓Confirm the one-time fee your distributor charges for changing power (approx. €11 per change).
Power Optimization Decision Matrix
| Symptom | Diagnosis | Recommended Action |
|---|---|---|
| Breaker (ICP) never trips even with all appliances on | Power is likely oversized | Calculate peak usage and consider lowering kW |
| Breaker trips occasionally during peak hours | Power is correctly adjusted or slightly tight | Avoid simultaneous use of high-consumption appliances |
| Breaker trips frequently | Power is undersized | Increase power by 0.5 kW increments |
| Fixed term is more than 40% of the total bill | Severe power/tariff imbalance | Immediate forensic audit required |
Lowering power usually costs around €10-11 as a processing fee from the distributor.
The German Teleworker's 90 m² Oversize in Valencia
A German digital nomad teleworking from a 90 m² flat in Valencia had the default 5.75 kW set by the landlord years ago. The maximeter never recorded above 3.1 kW in 14 months of heavy home-office use. Lowering to 3.45 kW plus cancelling an unused 'asistencia eléctrica' service cut the fixed term by 32% and saved around €145/year.
Hallazgos
- ✓Contracted 5.75 kW vs. historical peak of 3.1 kW (logged over 14 months).
- ✓€4.50/month 'asistencia eléctrica' service never used, bundled at sign-up.
- ✓Effective bill drop of ~€145/year after right-sizing to 3.45 kW and cancelling extras.
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Preguntas frecuentes
Your data is yours
We process bills ephemerally. We don't store them, and we never sell your data to third parties.
Disclaimers
- Informational tool; not financial advice.
- We don’t guarantee savings: these are estimates.