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kW: What it is and why it costs you even without consumption
Respuesta rápida
A kW (kilowatt) represents the contracted electrical power, which is the maximum amount of energy you can use simultaneously in your home. In the
En 30 segundos
- ✓Locate the 'Contracted Power' section in your PDF bill.
- ✓Check if you have two different periods (P1 and P2) and their respective kW values.
- ✓Verify the price per kW/day to ensure it aligns with current market rates.
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Upload your bill and let our AI find the hidden kW costs in less than 30 seconds. No registration required.
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
Authorship, methodology and official sources.
Actualizado: 10 de enero de 2026
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Transparencia y fuentes
Authorship, methodology and official sources.
Actualizado: 10 de enero de 2026
Autoría
Equipo ahorr.ai
Auditoría energética (España)
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.
What is kW: what it is and why it costs you (without jargon)
To understand your bill, you must distinguish between kW (power) and kWh (energy).
The definition in one sentence
The kW is the measurement of electrical power that determines how many appliances you can turn on at the same time without the breaker tripping.
Where it appears on the bill
Look for terms like 'Potencia contratada' or 'Término fijo'. It is usually expressed as a number (e.g., 3.3 kW, 4.6 kW) multiplied by a daily price and the number of days in the billing cycle.
Why it matters (money, decisions, and typical traps)
The power term is where many companies hide their margins because users focus only on the energy price.
The most common error
Keeping the same power for decades. Modern appliances are more efficient; you might be paying for 5.75 kW when 3.45 kW would suffice.
The clue almost no one looks at
Check the 'Maximum Power Demanded' section. If your peak is 2 kW below your contracted power, you are literally gifting money to the utility company every month.
How to check it in 60 seconds (Auditor's Checklist)
You don't need to be an engineer to perform a basic audit of your kW.
What to look for in the PDF
Search for the 'Datos del contrato' section. Verify the exact kW figure and see if there are two periods (Peak and Valley). Often, people pay for high power in both, even if they don't need it.
What to note for comparison
Write down your 'Price per kW/year'. If it's significantly higher than the regulated price (PVPC) or top-tier free market offers, you have a 'vampire' cost.
If you want certainty: autopsy your bill and decide with numbers
Manual checks are fine, but an automated forensic audit provides the evidence needed to act.
What ahorr.ai detects
Our tool identifies if your power is oversized, if you have hidden maintenance services, and if your price per kW is inflated compared to the current market.
What to do with the result
Once you have the report, you can call your company with specific data or switch to a provider that offers a more adjusted rate, saving you from 'vampire' costs.
Forensic Checklist for your kW and Contracted Power
- ✓Locate the 'Contracted Power' section in your PDF bill.
- ✓Check if you have two different periods (P1 and P2) and their respective kW values.
- ✓Verify the price per kW/day to ensure it aligns with current market rates.
- ✓Compare your maximum power peaks (usually found in the consumption graph) with your contracted kW.
- ✓Identify any 'additional services' or 'maintenance' linked to the power term.
- ✓Decide if a reduction of 1 kW or more is feasible based on your peak usage.
kW Glossary: Deciding Your Strategy
| Term | Forensic Meaning | Impact on Bill |
|---|---|---|
| kW (Kilowatt) | The capacity of your installation to run appliances simultaneously. | Fixed cost paid every day, regardless of consumption. |
| Contracted Power | The limit agreed with the provider before the 'leads' (ICP) trip. | The largest fixed portion of your monthly invoice. |
| Power Peak | The maximum amount of kW you actually used at a specific moment. | The evidence needed to know if you can downgrade and save. |
| Término de Potencia | The specific price multiplied by your kW and billing days. | The 'toll' you pay for being connected to the grid. |
Reducing contracted power is often the fastest way to lower a bill without changing habits.
The Retiree's Hidden 'Vampire' Service
A retiree in Madrid, tired of telemarketing calls, decided to analyze his bill. He had 4.6 kW of contracted power but his actual peaks never exceeded 2.8 kW. Upon closer inspection, he found a maintenance service camouflaged in a small line item.
Hallazgos
- ✓Contracted power of 4.6 kW vs. actual peaks of 2.8 kW.
- ✓A hidden maintenance service costing 6.99 €/month.
- ✓An effective price of 0.23 €/kWh, significantly higher than market alternatives.
No bill at hand?
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Related guides
Preguntas frecuentes
Why trust ahorr.ai?
We offer a privacy-first experience: ephemeral processing, no commercial calls, and AI trained specifically for the Spanish market.
Disclaimers
- Informational tool; not financial advice.
- We don’t guarantee savings: these are estimates.