Spain's electricity bills: unused contracted capacity inflates costs

Your electricity bill is paying for capacity you don't use

How much do you pay each month for contracted capacity you never actually use? That's the question that opens the analysis of almost any household electricity bill, and the answer usually hurts. The first thing checked in a bill review is always the same: contracted capacity above what is actually consumed. It's what you pay even if nothing is switched on all month, and that's where much of the overlooked overcharge hides. The second focus is the wrong tariff: time-of-use pricing when consumption happens during the day, a fixed rate when an indexed one would suit better, or the other way round. The third is the services bundled into the bill —maintenance, payment protection, assistance— slipped in during the sign-up call that nobody remembers agreeing to.

Contracted capacity you pay for without using

The most common case comes with a name and figures. A home with 3.5 kW contracted in both peak and off-peak periods discovered, after checking its distributor's portal, that its actual consumption never even reached 2.5 kW. It dropped to 2.7 kW to keep a margin in winter. The saving: around 70 euros a year. The small oversight, as the conversation sums up, is not trivial. Capacity is a fixed charge paid month after month, whether anything is switched on or not, and anyone with oversized capacity is giving money away with a consistency many savers would envy.

The full calculation, with grid charges and capacity terms broken down line by line, is where the differences that really matter to the annual bill appear.

How to know if your tariff is the right one

The answer depends on your consumption pattern, and that's what almost nobody stops to look at. Someone with panels and a battery, like the case of a home with 500 kWh monthly average and 150 euros paid over the whole year, has off-peak hours with practically no effect: when there's no sun, the battery kicks in. For that profile, cheap off-peak hours make no difference. For those without solar panels, however, a time-of-use tariff only pays off if consumption is concentrated in the cheaper periods.

Some argue that the PVPC (Spain's regulated electricity tariff) is the one and only answer. Against it weighs the fact that the indexed price moves with the market and forces you to watch when you run the washing machine. The fixed alternative, with a locked-in price at all hours, gives peace of mind but can work out more expensive if the market falls.

Bundled services and bills nobody reads

The third front is the one that sparks the most outrage: the maintenance, payment protection or assistance plans that appear on the bill without anyone remembering requesting them. They're signed up for during the sign-up call, amid the rush and the fast-spoken script, and then months go by with them adding up. The advice is always the same: the full bill in PDF, with CUPS (Spanish supply point code), grid charges and a breakdown of capacity and energy terms, because with a few scattered figures you only get a rough estimate. And never post it on a public site: it carries your name, address and sometimes even your account number.

The paradox is that the tool for comparing already exists and is free: the CNMC (Spain's energy regulator) comparator lets you enter the data anonymously and see alternatives without showing your bill to anyone.

With these savings on the table, switching suppliers should be happening on a massive scale. Yet only a minority actually checks their bill. And meanwhile, contracted capacity pays for itself, month after month, without anyone switching anything on.