British Gas owner Centrica (LON:CNA) forecast overall earnings in line with hopes, but said UK retail margins would take a hit from lower household bills.
Centrica said it had made good progress despite continued weakness in commodity prices and power generation margins, but it said the full-year result would depend on weather and asset performance in the last few weeks of the year.
It expected UK residential energy supply margins to be within the range of the last few years, but with margins in the second half materially lower than the first half following a second 5% reduction in residential gas tariffs.
Oil & gas exploration and production (E&P) was now expected to top 75 million barrels of oil equivalent, higher than previous guidance, reflecting continued good well performance.
The division was on track to reduce capital spending to below £800mln this year and less than £600mln in 2016.
It also expects E&P to achieve an annual reduction in cash production costs of £100mln relative to 2014.
Nuclear operational performance was good and it expected its full-year share of output to be higher than in 2014.
In UK gas storage, it anticipated the sale of cushion gas from the Rough storage field to broadly offset the negative impact on 2015 profitability from operating limitations of the Rough wells.
Chief executive Iain Conn said: "I am pleased with our progress since we announced our strategy in July. 2015 has been a difficult year, and against challenging external factors Centrica is establishing a solid base.
"We are seeing underlying performance improvement against a softening commodity market."