Extra Energy is a challenger energy supplier, launching in the UK in April 2014. Their ambition is to revolutionise the energy market and save customers across the country hundreds of pounds on their energy bills every year. Extra Energy is the fastest growing energy supplier ever in the UK, and currently has more than 500,000 customers. The secret of their success is their technology having built its own customer management and billing system, enabling the supplier to offer a much lower cost-to-serve than its competitors. The business is already a proven concept in Germany, where it has contracted more than 2 million customers in less than 5 years.