Video: The £1 billion cost of the great 'price cap' energy bill hike

But experts have calculated that the energy price cap brought in by government regulator Ofgem last month will now cost those 11 million households £1.29 billion a year from April.

Perth-based SSE yesterday joined the rest of the "big six" energy companies in raising its standard variable energy tariff to meet the latest price cap brought in by the government regulator Ofgem.

And it prompted a backlash from consumer organisations who have become worried about the effect of the average £117-a-year rise will have on households.

Source: Parliament TV

Ofgem said when the cap was brought in in January, to be initially set at £1,137 per year for a typical dual fuel customer paying by direct debit which it said would bring household bills down by around £76 per year on average, saving over £830 million over a year.

But within a month, on February 7, the new cap raised typical UK default and standard variable gas and electricity tariffs by £117 to £1,254 a year from April 1 due to hikes in wholesale energy costs.

READ MORE: Energy price cap branded "con" as Scots energy bills set to rise by up to £184 a year

Theresa May said in the House of Commons as the first of the price rises was already made known last week that the cap "provided protection to 11m households and energy suppliers will no longer be able to rip off customers on poor value tariffs".

She insisted: "It will save consumers a total of 1 billion pounds on their bills annually."

But it was further estimated yesterday that 1.1m Scots households will feel a collective £129m hit as energy companies raise their prices to mirror Ofgem's cap hike from April 1.

SSE's 10.22% increase from April 1 will see the typical customer on a standard tariff pay £117 more a year to reach £1,254 and mirrors rises announced by Glasgow-based ScottishPower and Scottish Gas.

The increase will affect around 2.1 million SSE customers, while those remaining on standard tariffs. SSE's typical dual fuel Pay As You Go customer will see their prices increase by around £106 a year, or a total of £1,242.

Ofgem said previously those affected would still pay a "fair price" for their energy as the increase reflects a genuine rise in underlying wholesale costs, rather than provider profiteering.

Citizens Advice Scotland said it was "increasingly concerned" about the impact of energy costs on household budgets despite the price cap.

Marcus Wilson, energy policy officer with CAS said: “It’s obviously disappointing that all of the Big Six have now raised prices. Energy is becoming increasingly unaffordable as wholesale prices rise, putting more strain on household budgets and pushing more Scots into fuel poverty.

READ MORE: Theresa May warns Big Six ‘more to be done’ as energy prices capped

"25% of households in Scotland are in fuel poverty, and Citizens Advice Scotland is increasingly concerned about the impact of energy costs on household budgets, this is one of issues that people visit our Bureaux about regularly. We know that people who struggle with their energy bills are more likely to need extra support.

“Earlier this month the price cap was increased: although this was always meant to fluctuate with wholesale prices, this was a very large rise. The price cap is there to protect consumers from the most expensive tariffs, however it doesn’t protect them from overall energy price rises which is what we are seeing from the most well recognised energy brands.

"Although we are aware that the market for energy deals is contracting we would always tell customers to shop around and switch when they can – it’s the quickest way to save money, and smaller operators outwith the Big Six might have more suitable deals for customers. This sits alongside longer term solutions like installing energy efficiency measures or better boiler controls at home."

The consumer organisation Which? has been concerned that energy companies are holding back their cheapest deals leaving customers short of a choice of good-value deals to switch to as prices rise.

It said that the number of cheap deals has crashed as suppliers adjusted their operations in the run-up to the cap’s implementation in January - and that things have since got worse.

In December Which? found that the number of energy deals costing less than £1,000 a year for medium users had dropped from 77 in January to eight. As of Monday, February 4, there were just six.

USwitch which has called the energy price cap a "con" said that before it was brought in energy suppliers were already raising prices and justifying it by pointing to wholesale costs as a main reason.

It has estimated that pensioners in Scotland on standard variable tariffs are more likely to be looking at around a £130 increase, on the assumption that they probably live in slightly smaller properties with fewer people at home with them.

Richard Neudegg, the price comparison site's head of regulation said: "It's been a bad week for Scottish energy customers on a standard tariff as Scottish Gas, ScottishPower and SSE have all announced that they intend to price up to the level of the increased energy price cap from April. It only took two weeks since Ofgem announced the new rates for all of the big six energy suppliers to announce their price rises."

Official figures show that in 2017, before the cap came in, one in four households across Scotland were estimated to be in fuel poverty, by spending more than 10% of their income on household fuel to maintain satisfactory heating. The Scottish Government has a proposed new statutory target for fuel poverty that in 2040, no more than 5% of households in Scotland are in fuel poverty.

The latest bills hike came as Scottish Gas owner Centrica - a key player in the North Sea - warned that its financial performance will be hit by the energy regulator’s tariff price cap. But it reported adjusted operating profits had risen 12 per cent to £1.39 billion It anticipated a one-off £70 million hit in the first period of the cap.

Yesterday ScottishPower recorded underlying profits of £1.543 billion in 2018 compared with £1.215bn in the preceding year.

And in September, SSE has issued a profit warning, partly blaming the looming price cap while announcing profits for the six months to September 30 of around £293m, half of the £586m achieved the previous year.

The cap followed an announcement by the competition watchdog last year suggesting that radical reforms to the way the insurance, mortgage, mobile phone and broadband markets operate after finding that loyal customers are being ripped off to the tune of £4bn.

First introduced on January 1, 2019, the energy price cap set a limit on a unit price of energy and a maximum standing charge. This meant energy suppliers had to charge consumers a price either at the level of or below the cap.

The energy watchdog said it would increase the typical price cap for UK default and standard variable gas and electricity tariffs by £117 to £1,254 a year from April 1. The price cap for UK pre-payment meter customers will also rise - typically by £106 to £1,242 a year from April 1.

Ofgem said rising wholesale costs were responsible for the majority of the increase (£74). It said the allowance for wholesale costs now makes up more than a third of the overall cap.