* E.ON expects profits in renewable energy business to rise
* Banks on partners in onshore wind park expansion
* Says to expand in U.S., Europe; looking at new markets
* E.ON has 10,900 MW of renewable capacity, 17 pct of total (Recasts, adds quotes, background)
BERLIN, Aug 26 (Reuters) - E.ON, Germany's biggest utility, is banking on investors to help it catch up with European rivals in renewable power, unable to shoulder large projects on its own as it battles to cut debt.
E.ON's conventional coal and gas power plants have been hit hard, in part because of a massive surge in renewable energy generation in Europe which industry experts say was ignored by German utilities for too long.
The group's board member in charge of renewables told Reuters green energy was now growing as a source of profits for the utility, but that it needed help from investors for large wind power projects as its own investments were being cut to tackle its 29.7 billion euros ($39.2 billion) of debt.
"We have a big pipeline of developed onshore (wind) projects. But E.ON can no longer meet the capital needs for these projects on its own," Mike Winkel said in an interview.
"Therefore, financial investors are very welcome to join and it turns out they see this market as being quite attractive."
Drawn by annual returns of up to 20 percent, pension and infrastructure funds have started to buy into large wind parks as an asset class.
Last month, Denmark's DONG Energy A/S agreed to divest 50 percent of a German offshore wind farm project to a group of Danish pension funds, freeing up capital to expand its offshore wind business.
E.ON could do with the help, as it expects annual capital expenditure to halve to about 4 billion euros in 2016 from more than 8 billion last year.
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E.ON's smaller German peer RWE has also said it needs the help of external investors for big wind power projects, which swallow investments of at least 1 billion euros and carry greater risks when erected offshore.
Winkel said the growing role of renewables was partly down to shrinking profits from conventional power generation.
"Generation from renewable energy sources grows as conventional generation continues to fall - we're witnessing our own energy transformation," he said.
Last year, renewables accounted for just over 15 percent of E.ON's earnings before interest, tax, depreciation and amortisation (EBITDA), which fell by 14 percent overall.
That put it far ahead of local rival RWE, where renewables accounted for just 4.5 percent of core profit.
But it still lagged Spain's Iberdrola, which made more than a fifth of its EBITDA from renewable energy last year.
E.ON has focused on wind and has become the world's third-biggest owner of offshore wind capacity, behind Denmark's DONG and Sweden's Vattenfall.
Since 2007, it has invested about 10 billion euros in renewables. Including hydro power, E.ON has about 10,900 megawatt (MW) of renewable capacity worldwide, accounting for about 17 percent of its total generation portfolio.
For now, however, most of its wind parks are in the United States and Britain, where the pressure on conventional power sources is less intense than in Germany.
Winkel said E.ON aimed to further expand its renewables presence in Europe and the United States, and is also working on onshore wind parks in Turkey.
(1 US dollar = 0.7577 euro) (Additional reporting by Tom Kaeckenhoff; Editing by Tom Pfeiffer and Mark Potter)