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How much power does my home need? How to calculate it and how much it costs to change it
Your home isn’t haunted by a poltergeist. If the RCD trips every time you switch on the oven while the ceramic hob is on, the problem is that your electricity contract provides less power than your home actually needs.
Your contracted power is the maximum amount of electricity you can use at any given time. When you exceed it, the system automatically cuts off the power supply. What may seem like a mysterious electrical fault is actually just a sign that your installation is demanding more capacity than your contract allows. How much power you actually need depends on your home.
Why contracted power matters: the fixed cost you pay even if you consume no electricity
To better understand your electricity bill, the first step is to distinguish between two concepts that often get confused:
- A kilowatt (kW) represents power, that is, the maximum amount of energy your home can draw from the grid at any given moment. Think of it as the width of a water pipe: the wider the pipe, the more water can flow through it at once, allowing you to turn on multiple taps at once without overloading the system. This item appears on your bill as the ‘power charge’, a fixed cost you pay for having that amount of capacity available to you 24 hours a day.
- A kilowatt-hour (kWh) is your actual electricity consumption, the total amount of ‘water’ that has flowed through the pipe.
Understanding and adjusting your contracted power is important for financial reasons, since the higher the contracted power, the higher your fixed costs. It is estimated that you can save around €50 per year for every kW you are able to reduce in your contract.
On the flip side, the Power Control Switch (ICP) will cut off your power supply for safety reasons whenever you exceed your contracted power by multitasking, such as running the washing machine while the oven is on.
The power ratings you can sign up for (and only these)
Standardised power levels are the specific ratings you can sign up for, depending on the type of electrical installation you have:
- Single-phase (up to 14.49 kW, for residential use).
- Three-phase (up to 43.648 kW, for industrial use).
You must stick to these tiers based on your household’s needs when setting up a new electricity connection, changing your contracted power, switching tariffs, or changing supplier. In addition, distribution companies allow changes in increments of 0.1 kW, as long as you don't exceed the technical limits of your installation.
| Instalación monofásica (230 V) | Potencia contratada |
|---|---|
| 230 V | 1.15 kW |
| 230 V | 2.3 kW |
| 230 V | 3.45 kW |
| 230 V | 4.6 kW |
| 230 V | 5.75 kW |
| 230 V | 6.9 kW |
| 230 V | 8.05 kW |
| 230 V | 10.35 kW |
|
Perfil de la llar |
Equipament tipus |
Potència recomanada |
Notes clau |
|---|---|---|---|
|
Estudi / pis petit sense A/C |
Llum, nevera, TV, rentadora |
0,5 % de 40 = 0,2 € 2,3 – 3,45 kW |
Sense A/C ni calefacció elèctrica. El valor mínim viable per a la majoria de les llars urbanes. |
|
Pis mitjà amb A/C |
+ Aire condicionat 1 split |
4,6 – 5,75 kW |
L'split d'A/C pot exigir 1–1,5 kW en arrencar. Sense ell, 3,45 kW sol ser suficient. |
|
Casa amb cuina elèctrica i A/C |
+ Vitro/inducció A/C |
6,9 – 8,05 kW |
La inducció (fins a 3,5 kW) i l'A/C simultanis són els responsables del pic màxim. |
|
Amb cotxe elèctric |
+ Carregador Waybox 7,4 kW |
8,05 – 10,35 kW |
Clau: Waybox només funciona si hi ha capacitat sobrant. Si carrega de nit (vall), la resta de la casa dorm. |
|
Amb aerotèrmia |
+ Bomba de calor 3 – 5 kW |
8,05 – 10,35 kW |
L'aerotèrmia té cims d'arrencada. Revisar amb l'instal·lador el pic màxim real de l'equip. |
If you would like an exact figure for your specific situation, we recommend using our power calculator, which can provide an estimate in just one minute based on your consumption habits.
How having an electric vehicle changes your calculation
The number of electrified vehicles in Spain continues to grow in 2026. This year, the number of electric and plug-in hybrid vehicles has exceeded 600,000 units, a figure that reflects how firmly this technology has established itself in the market. In this context, home charging is becoming an increasingly common requirement for users.
A standard charger, such as the Waybox, requires approximately 7.4 kW. However, it is important to factor in load balancing, an intelligent system that automatically adjusts your car's charging power based on the electricity being used elsewhere in the home. For example, if your contracted power is 6 kW and your household appliances are currently using 1 kW, the charger will use the remaining 5 kW.
How having an air-source heat pump changes your calculation
Air source heat pumps are highly efficient for climate control, but their start-up peaks can exceed 5 kW. In homes that combine an air-source heat pump with an electric cooktop, the required power is very likely to fall within the higher tiers.
If you are considering installing an air-source heat pump in your home, it is essential to review your contracted power beforehand to avoid either falling short or paying for more than you actually need.
How to tell if you have more power than you need
If you suspect you are overpaying, there are two reliable ways to check:
- The circuit-breaker test: turn on all the electrical appliances in your home at the same time (air conditioning, oven, ceramic hob, etc.). If, after switching them on one by one, the breaker does not trip, it is a clear sign that you have more contracted power than you actually need and your electricity bills are unnecessarily high.
- Digital check: for a more accurate analysis, you can log into the Endesa Customer Area. There, you will find a record showing the maximum power demand hour by hour over the past year. If your highest peak never comes close to your contracted power, you have room to reduce it.
Dual power under the 2.0TD access tariff: when does it make sense?
Since the introduction of the current access tariff regulations, you have had the option of signing up for two different power levels for different times of the day. This can be particularly useful if you want to save on your electricity bill by taking advantage of time-of-use periods.
For most users, the most sensible approach is to maintain a lower power during peak hours and sign up for higher power during off-peak hours (nights, weekends, and public holidays), especially if you need to charge an electric vehicle or schedule high-consumption appliances to run overnight. However, you should keep in mind that changing your home's contracted power comes with a cost.
How much it costs to change your contracted power and when it pays off
Changing your contracted power incurs a fee charged by the distribution company, which is added to your electricity bill. It is important not to make this decision lightly, since, as a general rule, only one change per year is allowed.
Reducing your contracted power costs approximately €9, regardless of how much you decide to lower it by. It is an investment that pays for itself quickly, as the savings will offset the fee within a few months.
Increasing your contracted power, on the other hand, is more expensive. The cost is approximately €46 for every kW you decide to add. In addition, if your electrical installation is more than 20 years old, or if the new contracted power exceeds its maximum certified capacity, your distribution company will require a new Electrical Installation Certificate (CIE), which represents an additional expense.
Before changing your home's contracted power, make sure you have carefully calculated your actual requirements.
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You don't need to adapt to Endesa's tariffs because they adapt to you. If you go to our catalogue you can compare the different tariffs for yourself. Or if you prefer, you can answer a few questions and we will take care of comparing all the different electricity and gas tariffs and then make a customised recommendation.
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You don't need to adapt to Endesa's tariffs because they adapt to you. If you go to our catalogue you can compare the different tariffs for yourself. Or if you prefer, you can answer a few questions and we will take care of comparing all the different electricity and gas tariffs and then make a customised recommendation.
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