A year after I signed my electricity contract with Naturgy, the email arrived: a 10% price increase.
No warning. No negotiation. Just a bigger bill.
I'd heard that switching electricity providers in Spain is about as easy as switching internet providers. So I tested it on myself. What follows is what actually happened, how Spanish electricity bills are really structured, and a few things I wish someone had told me before I picked up the phone.
Switching is easier than you think
An electricity contract in Spain is not a commitment you have to live with. The market is open, and moving from one provider to another is designed to be simple.
To find the cheapest option, I used a service that compares tariffs based on how you actually use electricity: when you use it, and how much contracted power (potencia) you have.
The process started with one upload — my latest bill. I submitted it in the evening. They called me the next morning.
What happens on the call
They re-checked my usage and asked whether I really needed the 8 kW of contracted power I had. Then they offered two of the cheapest plans they could find: Octopus and TotalEnergies. With relatively high contracted power, Octopus came out slightly cheaper.
They read out the full offer. When I agreed, they recorded my consent and handled the entire switch themselves. I didn't visit an office or sign anything in person. The new company sent me a contract, the old one was cancelled, and that was that.
It all happens in Spanish. My level was only A2, and it was enough — but you'll want enough Spanish to follow the numbers and confirm the terms.
How a Spanish electricity bill actually works
Before you compare anything, you need to know what you're comparing. A Spanish electricity bill has two main parts:
- Standing charge (potencia): what you pay for contracted power, split by time period.
- Energy charge (consumo): what you pay for the electricity you actually use.
Energy pricing comes in two flavours: a flat rate (one price all day) or a time-of-use rate split across periods — day, night, and sometimes an evening peak.
Here's the catch: with time-of-use pricing, you cannot eyeball which tariff is cheaper. It depends on your consumption pattern across those periods. That's exactly how people get talked into the wrong plan over the phone.
Check your real peak before you pick a tariff
When the switching service asked about my contracted power, I answered from memory: 8 kW, based on a rough mental list of my appliances. That number was a guess.
Then I checked Datadis — a free platform run by Spain's distribution companies (the ones that own the cables and read your meter, not the provider you pay). You register with your supply number (CUPS), and it shows your actual electricity use, hour by hour, going back months. My real peak over the whole year was 6.93 kW. I had been paying for headroom I never used.
So I'm dropping my contracted power to 7.5 kW. The change costs a one-off €10.94, and it saves about €2.41 per bill. Small, but it adds up — and it's money I was paying on a number I had invented.
Before you compare tariffs, get your actual peak from Datadis.
Two things I didn't know (and you should)
1. A switching service can beat the provider's own website
The Octopus tariff I was offered through the comparison service was cheaper than the same Octopus tariff listed on Octopus's own site. Had I gone directly to Octopus, I would have paid more. Check both.
2. Every bill carries a free government comparator
This is the one I wish everyone knew. Every electricity bill in Spain includes a link and a QR code to the official CNMC energy offers comparator (Comparador de ofertas de energía). Scan it at comparadorofertasenergia.cnmc.es, and you can see what you would pay with other providers — straight from the regulator, no salesperson involved.
Before any switching call, scan that QR code on your bill — you'll walk in already knowing the answer.
Then the retention call came
The day after I switched, Naturgy called. Would I come back? They offered slightly lower contracted power and a slightly lower energy price — on the surface, about 5% cheaper. I'd told them what Octopus offered, so surely they wouldn't offer the same thing, or worse. I agreed to switch back.
Only afterwards did I do the thing nobody does on a sales call: build the calculation myself in Excel.
The reality was less flattering. When I put the two offers side by side in my own spreadsheet, the Naturgy deal came out about €1–2 a month more than the Octopus plan I had just left. Still below my old pre-increase price — but not the saving the sales call had implied. So I stayed on Naturgy anyway. For a couple of euros a month, it wasn't worth restarting the whole switching process.
Never agree to a tariff on the phone. Get the numbers, run them, then decide — what sounds like "5% cheaper" is often just a nicer-sounding number.
One more trap: no numbers in writing
On both calls, I asked for the offer in writing — an email with the figures — so I could compare it properly. They wouldn't send one. Offers are read out over the phone, and that's it.
So you get two options: agree to what you just heard, or turn it down on the spot. There's no "send me the numbers and I'll get back to you."
That's why the homework has to come first. Get your real peak from Datadis, benchmark the market with the CNMC comparator, and have your current tariff ready. Then the call is a five-minute decision, not a gamble.
Make the decision in five minutes
The real cost depends on your own consumption pattern, not the headline price. That's the gap that tripped me up — try the free Electricity Bill Calculator on Spanified: plug in your current tariff and the new offer, and see the actual difference.
So next time someone calls you with a deal, you don't have to guess. Have your current figures ready, enter the new ones, and read the number.