The Glasgow-based group said it now plans to spend about £235 million for the full year, an increase of £20m on its previous guidance, reflecting additional investment in diesel generators and its North American gas fleet.
Interim chief executive Angus Cockburn said the firm had turned in an “encouraging” first-half performance, although currency exchange effects took the shine off the rise in sales.
Underlying revenues grew 12 per cent to £768 million for the six months to the end of June, but the strength of sterling saw pre-tax profits drop 9 per cent to £132m.
Cockburn said the group, which provided power for the World Cup in Brazil and Glasgow Commonwealth Games, faces a “challenging” second half because of cautious customers and strong trading a year ago.
Investors will receive an interim dividend of 9.38p a share on 3 October, up 3 per cent on last year’s payout.