Electrical power capacity

How to optimize your consumption and select the best option for your home

The power capacity you set for your home impacts your electric bill, your home's energy efficiency, and how many appliances you can use simultaneously. That's why it's important to understand what electric power capacity is, how it's calculated, and what you should consider when deciding yours.

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What's electrical power capacity?

The electrical power capacity set for a building or household (in Spanish, potencia eléctrica contratada) is the maximum amount of energy that can be consumed at a given moment. It's measured in kilowatts (kW) and ultimately determines how many electrical appliances you can use at once without tripping the circuit breaker. For example, if you want to use your oven, washing machine, and the air conditioning all at the same time, you need to have enough power capacity to cover that amount of consumption, or else the breakers will flip and the power will go out.

The fixed charges on your power bill are largely related to power capacity. The greater the power capacity, the more you pay each month, as costs are affected by the level of power capacity you select.

Factors to consider when deciding the power capacity

Are you wondering what level of power capacity you need? It depends on a variety of factors. Here are the most important ones:

Home size
The bigger your home, the more power you'll need to cover all your energy consumption.
Number of occupants
A person living alone doesn't need the same power capacity as an average-sized family or a house full of roommates, where appliance use is more frequent and simultaneous.
Appliance usage
If you use high-powered appliances such as the oven or a hair dryer, you'll need more kilowatts of power capacity.
Heating and cooling
Systems such as air conditioning or electric heating directly influence the amount of power needed.
Consumption habits
Lifestyles and routines also come into play. If you or someone you live with works from home, this will likely result in higher energy consumption over the course of the day from the use of electric devices, heating, or air conditioning.

How can I calculate the power capacity I need?

To calculate the right power capacity for your home, you need to figure out how much energy is necessary to power all the appliances in your house at once. You'll need to consider both the amount and kinds of electrical devices, as well as how frequently they're used. Be sure to measure your consumption at moments of peak demand: this will help ensure your power capacity is enough to prevent the breakers from tripping.

Calculating power capacity

Calculating the right power capacity for your home is key in optimizing consumption and lowering your bill. In Spain, families living in homes with 90 to 110 square meters (970 to 1,200 square feet) often need from 4.6 kW to 5.75 kW per month, depending on the number of appliances they have and how frequently they're used.

Example: how to calculate the power capacity for a family of four

Look up your installed capacity:

The first step is to check the information about your home's electrical system. In Spain, you'll need to find your home's Certificado de Instalación Eléctrica (electrical installation registration) or CIE. This technical document certifies that your home's wiring and connections meet all safety regulations and states the maximum power load that can be carried. This limit will depend on your home's age and other characteristics.

Make a list of your appliances:
Take stock of all the electrical devices you have at home and take note of how many kilowatts are consumed by each on average. You can find this information in user's manuals and on labels. Remember that it usually refers to usage in real time, as opposed to per month or year.

Here are some common household appliances and their average consumption:

Refrigerator (always running): 0.8 kW
Vitroceramic stovetop (two burners): 1.5 kW
Oven: 2.5 kW
Microwave: 1 kW
Small appliances (toaster, blender, etc.): 0.5 kW
Washing machine: 2 kW
Air conditioning or electric heater: 2.5 kW
Hair dryer: 2 kW
Television: 0.1 kW
Lighting: 0.4 kW
Computer: 0.25 kW

Take simultaneous use into account:
Obviously, you don't usually use all your home's appliances at once, but you will need to identify the moments of peak consumption.

For example, at peak consumption hours you might have all of the following plugged in and running:

Refrigerator (always running): 0.8 kW
Television: 0.1 kW
Lighting: 0.4 kW
Air conditioning or electric heater: 2.5 kW
Washing machine: 2 kW

This would add up to 5.8 kW at a moment of intensive use.

Assess your results:
To prevent the power from being cut off during use, your home's power capacity should always be higher than the sum of all your appliances being used at once.

If this sum is very close to your current power capacity, you might need to increase the power capacity to prevent overloads and circuit breakers tripping. On the other hand, if the maximum amount of possible consumption is well below your power capacity, you might want to think about having your power capacity lowered so you can pay less.

Add a safety buffer:
To cover unanticipated increases in consumption, it's advisable to add 0.5 to 1 kW to your potential power consumption total.

In our example, if the sum of simultaneous use is 5.8 kW, another 0.5 kW could be added as a safety buffer for a total recommended power capacity of 5.75 kW for this family.

Repsol and electrical power capacity

Every home and business has its own consumption habits. That's why, at Repsol, we adapt to this diversity with a range of energy plans to help you avoid any unnecessary expenses. In addition to offering a practical means of managing energy consumption, these plans are also a place where we can put our innovative technology to work — for example, in advanced monitoring of electricity consumption. This technology, now available on the Repsol Vivit app, lets users look up and keep track of their electricity consumption, set savings goals, and receive personalized recommendations to optimize their energy use.