Consumption data from the supplier revealed that the average cost of energy on 25 December is about £5, compared to an average of £2.96 per day at other times of the year.
The offer comes after the successful launch of the Power Up tariff, which is the first energy plan in the UK to allow customers to buy energy in packages from one day up to 180 days, upfront and at a set price with no standing charge.
Scottish Power global retail director Neil Clitheroe said: “We want our customers to have even more control over the energy they use, and how much they spend on their energy costs. Power Up can let them do that.
“This truly is the start of the age of personalised tariffs, and uses real consumption data to calculate a personal daily price. We believe it will encourage customers to be more conscious of their energy usage, because they will want to make their days of energy last longer.
“This Christmas is likely to be one of the biggest days of the year for energy consumption for most people, and we want to give our Power Up customers an early present by giving them their Christmas Day energy on us.”
The additional costs on Christmas day come from activities such as charging a new mobile phone (4p), two sets of Christmas tree lights (13p) and an electric oven being on for around 6 hours (£1.17).