To simplify - Iberdrola has a day and night tariff - where you pay fractionally more during the day, but a lot less at night.
In the winter HOURS FOR SAVINGS
From 22:00 to 12:00. From October to March
HOURS FOR SAVINGS
From 23:00 to 13:00. From March to October
Roughly speaking - it's about half in the savings hours - so if you can time it use your washing machine / dish washer / boiler moreso in the evening or early morning within these time periods given, you'll save considerably.
We also kicked out the old boiler (no jokes please) which ran at a maximum of 2kw, put in an Ariston Eco friendly one which maxed out at 1.5kw - and has a learning function, gets smart as learns when you use your hot water. This I think may have helped a lot, as boilers use a lot and the old one was 10 or so years old. Bill dropped the month after noticeably.
Depending on the time of year, electricity bills are between 30%-50% lower than last year before we had the day/night tariff and the eco boiler. We also put a new fridge in, though I don't think that makes so much difference - though as a rule of thumb, I will not buy any new electrical item, without an A+ rating.
Last months bill was the highest we've seen so far which was around €140 for one month, which seems high (our bills always high) - but we have not been using wood to burn yet, been using radiators - and the bill is still less than last years of €200+ wood, which in a month wasn't far from another €100.
However, whilst the rate is less day/night - they still have the usual BS charges there is no getting away from - maintenance of supply (always felt that was an insult), IVA etc. A fair old percentage of the rest of the bill, this is where people end up scratching their heads - going why is my bill so much when I used little electricity
More info, in English