Short answer: a 90 m² flat without an induction hob or an electric car runs comfortably on 3.45 kW. With induction or air conditioning, between 4.6 and 5.75 kW. If you are on 6.9 kW "just in case", you are very probably throwing money away every month.
Why this matters more than it seems
A Spanish electricity bill has two parts. The energy term is what you consume: go on holiday and it drops. The power term is what you pay for having a maximum amount of electricity available at any given moment, and it is charged for every single day of the billing period, whether you use anything or not.
That makes contracted power a fixed cost. You do not reduce it by switching off lights or running the washing machine at night. You reduce it only by contracting less.
Contracted power is billed per kW per day, every day of the year. Adjusting it produces savings automatically, without changing a single consumption habit.
Finding out what you have now
Look at your bill for potencia contratada or potencia facturada. You will see one or two values in kW. Since the 2021 reform you may have two: peak/standard (8:00 to 24:00 on working days) and off-peak (nights, weekends and public holidays). The off-peak figure can be higher at very little cost, because its regulated price is far lower.
How much you need: the real calculation
Do not add up the rating of every appliance you own, because you never run them all at once. What matters is the simultaneous peak: the worst moment of the day, when the most things happen to be on together.
These are the typical figures for the appliances that actually move the needle:
| Appliance | Approximate power |
|---|---|
| Induction hob (one zone in use) | 2,000 – 2,500 W |
| Electric oven | 2,000 – 2,500 W |
| Air conditioning (start-up) | 1,000 – 1,500 W |
| Washing machine (heating phase) | 1,500 – 2,200 W |
| Electric water heater | 1,200 – 2,000 W |
| Tumble dryer | 1,500 – 2,500 W |
| Microwave | 800 – 1,200 W |
| Fridge | 150 – 350 W |
| LED lighting throughout the home | 100 – 200 W |
A concrete example
Dinner on an ordinary Tuesday in a flat with induction: two zones on (4,000 W), oven preheating (2,200 W), fridge (250 W), lights (150 W) and television (100 W). Total: 6,700 W, or 6.7 kW. That household genuinely needs 6.9 kW.
The same flat with a gas hob: oven (2,200 W), fridge, lights, television and the washing machine running (1,800 W). Total: 4,500 W. It is comfortable on 4.6 kW, and could try 3.45 kW if the oven and washing machine never coincide.
The five-minute test
If you would rather not calculate anything, do this: on a winter day, at the busiest hour in your home, switch on everything you normally switch on. If the ICP — the power control switch in your consumer unit — does not trip, your current power is sufficient. If it has never tripped in a whole year, you almost certainly have more than you need.
Drop one step, live with it for a few months and observe. If it trips, step back up. There is no drama in getting it wrong: the worst that happens is that you reset a switch.
What changing it costs
The first modification within twelve months is free apart from connection rights, which the distributor may pass on in certain cases. A second change within the same year does carry a charge. So it is worth thinking it through once and doing it properly, rather than experimenting every couple of months.
You request the change from your supplier, not the distributor, and it usually applies from the next bill. Nobody needs to enter your home: the digital meter is reconfigured remotely.
Three mistakes I see constantly
Inheriting the previous tenant's power
The most common of all. You buy or rent a flat and take on the contract as it stands. But that figure was chosen by somebody with different appliances and a different life. Always review it in the first few months.
Over-contracting "just in case"
That safety margin is paid for every day, for years. If the ICP trips twice a year, resetting it is far cheaper than paying for an extra step across 365 days.
Confusing lower power with lower consumption
They are different things and need different approaches. Lowering power is a one-off administrative step. Lowering consumption means changing habits and equipment. Both are worth doing, but the first is free and the second takes effort.
When not to lower it
If you charge an electric car at home, use a heat pump as your main system, or work from home with demanding equipment, do not touch your power without doing the calculation. In those cases the simultaneous peak is real, and being short becomes a daily problem.
In summary
- Power is a fixed daily cost: it does not depend on what you consume.
- Calculate your simultaneous peak, not the sum of every appliance.
- If the ICP has never tripped in a year, you probably have more power than you need.
- The first change within twelve months carries no processing fee.
- Lowering power and lowering consumption are two separate levers.