SSE saw a 48.2% rise in pre-tax profits to £548.8 million in the first half of this year.

The increase was supported by a wet and windier summer in Scotland and Ireland which boosted renewable generation.

The Big Six supplier’s investment and capital spending was up 11.5% to £757.3 million, which included its largest capital project – the Caithness-Moray transmission link.

Its wholesale business saw profits of £159.6 million – similar to the 2013 level – following “an exceptionally low performance” during the same period last year.

However SSE claims to have made less than £5 profit per dual fuel customer in the first half of the year and with market conditions “continuing to be challenging” in domestic energy supply, profits are expected to be lower at the end of the year.

The number of retail customers fell from 8.58 million to 8.41 million by the end of September.

Alistair Phillips-Davies, CEO of SSE, said: “We’ve had a solid start to the financial year but half-year profits are only half the story. There are many variables in energy and so they should be treated with caution – that’s why we focus on full-year results.

“The last six months have seen us invest substantially in the UK’s energy infrastructure – committing one and a half times what we’ve made in profit in the first half of the year.”