With regards to E.ON, non-domestic energy supply profits decreased from 2009 to 2018, amounting to 56 million British pounds in the latter year. Despite this decline, E.ON was still the most profitable of the Big Six in terms of non-domestic supply. As for gains from domestic energy supply, British Gas far outperformed its competitors. In 2018, the Centrica subsidiary made close to 470 million British pounds compared to the 111 million British pounds generated by second ranked Scottish Power. Scottish Power increased their profits of this sector from just 12 million British pounds the year before.
For energy generation, SSE recorded a total profit of 381 million British pounds in 2018. This made it the most successful of the Big Six in that segment. EDF was the only company to have sustained a loss that year.
The number of complaints received by the major energy suppliers has notably decreased since 2013. Npower saw the most notable decline, from a peak of 8,303 complaints received per 100,000 customers in the first quarter of 2014. Five years later, in the first quarter of 2019, the most complaints were received by E.ON.