While consumers grapple with the impact of the dreaded price cap on their fuel bills, it has emerged that not all households are protected by it and some could be paying over the odds for their energy.

So-called green energy firms are exempt from the mechanism which sets a maximum price for what first can charge per unit of electricity or gas.

They include Good Energy, which claims to produce "fair-priced, transparent 100pc renewable electricity".

Customer Adam Stromanis from Burnham Deepdale in north Norfolk has an issue when it comes to pricing.

Before the recent price hike, the cap set a maximum charge of 28p per kilowatt hour (KWH) on electricity from April 1.

Good Energy, based in Chippenham, Wiltshire, had been charging Mr Stromanis 35 p/KWH from January, for supplying electricity to his three-bed cottage, which went up to 42 p/KWH from July 1.

His expected bill has more than doubled from £630 in August 2921, when he was paying 18 p/KWH, to £1,344.

Between October 1 and December 31, the cap is set to rise to 52 p/KWH.

Mr Stromanis, a 42-year-old maintenance engineer, only obtains his electricity from Good Energy and relies on oil for his heating.

He is now trying to change suppliers as he waits to hear how much his standard variable tariff will increase by.

"It’s important that other households check their bills because if they are with a green energy supplier they could be paying well above the price cap," he said.

"My current supplier has not at any point informed me that they are not subject to the price cap

"I thought all energy providers are and I’ve only heard about the price cap in the last couple of years. If I had known this was the case I would of tried again switching, "

In a statement, Good Energy said: "Alongside a small number of other suppliers, Good Energy is not subject to the price cap.

“In our case, this is due to our commitment to provide 100pc renewable energy from around 1,700 independent generators using solar power, wind power, hydroelectricity and biomass, supporting the transition to a cleaner and greener supply.

“In the meantime we appreciate this is an anxious time for customers while we try to manage risk in such a volatile market, and we always encourage them to contact our customer service team if they need to discuss other options. This can include helping them switch to a new supplier that is subject to the price cap.”