The survey of 3,505 people found 12% of consumers rated their bills as unaffordable, with increasing numbers of consumers switching to smaller suppliers, often because of lower prices.

The ‘Market Pulse’ report tracked the attitudes of consumers in Scotland over three years on a range of issues.

It also revealed a decrease in people using electricity to heat their homes and an increase in people using gas, laying out the challenges in the energy market as policymakers move to decarbonise heat and meet climate emissions targets.

Almost half of consumers could qualify for extra support through the Priority Service Register – but only a quarter of consumers are actually enrolled, it added.

CAS released the report ahead of potential changes to the energy retail market in Scotland, such as OVO’s takeover of SSE’s retail business.

The charity delivers advice and support to hundreds of thousands of people every year, and last year their energy advice saved consumers in Scotland around £1.3 million on their energy bills – on average around £232 each.

Dr Jamie Stewart, CAS Markets spokesperson, said: “This major report gives us a really useful insight into the state of the energy market in Scotland which policymakers in government and industry may wish to consider.

“It’s notable that more than one in ten consumers feel their bills are unaffordable. Our report highlights the key divide in the nation, with some appearing to manage the cost of energy while a significant proportion of society continue to struggle. We strongly believe that more needs to be done to ensure that the essential service of energy is affordable for everyone in Scotland.

“That affordability question appears to be driving some consumers to switch from a traditional Big Six supplier to smaller, newer companies. However, this comes against a backdrop of suppliers failing across the UK, with twelve companies failing between June 2018 to June 2019, affecting over 1 million consumers across the UK.

“The small fall in people using electricity and the increase in gas usage should also be considered carefully by policymakers. As mains gas remains the cheapest way to heat homes for most people, policymakers will have to make tough decisions about how we decarbonise household heating and how to support people with the associated costs.

“It’s also concerning to note too that only a quarter of consumers were enrolled in the Priority Service Register when nearly half were eligible. This is a vital scheme which delivers better support for vulnerable customers and more needs to be done to promote it.

“Consumers who feel they need support on energy issues can always turn to the Citizens Advice network in Scotland. We help hundreds of thousands of people every year and last year saved people on average £232 off their bill.”