Trump's campaign has promised to renegotiate the world's second biggest carbon-emitting country's role in a United Nations-led global agreement which many view as a lynchpin for government support for renewables investment.

The U.S. wind market -- the world's second-largest with 2015 installed capacity of 74,500 megawatts according the Global Wind Energy Council -- is a major market for European turbine manufacturers and EU utilities seek expansion there as sources of funding back home dwindle.

Shares in European renewable energy equipment makers and utilities with significant investments in the United States fell 3 percent to as much as 10 percent on Wednesday. The S&P Global Clean Energy Index <.SPGTCLEE> slid 2.6 percent to its lowest level since late June.

Shares in Denmark's Vestas (>> Vestas Wind Systems A/S), the world's biggest wind turbine maker, plunged as much as 10 percent in early trade before recovering to stand 6 percent lower. German peer Nordex (>> Nordex SE) fell 6 percent and Spain's Gamesa (>> Gamesa Corporacion Tecnologica SA), which is being merged with Siemens (>> Siemens AG), opened 3.4 percent lower.

Vestas said on its Twitter feed it would not speculate so soon after the election about the renewable energy sector during Trump's presidency.

"Wind and renewable energy have broad bipartisan support. Polls show that almost 80 percent of Trump supporters want more wind farms built in the United States," it said.

Some 35 percent of Vestas' total order backlog comes from the Americas, of which a majority from the United States.

Shares of European utilities invested in U.S. wind and other renewables lost several percentage points on concern that a Trump administration would reduce government incentives.

"Mr. Trump has in the past displayed negative attitudes towards wind, calling wind turbines 'environmental disasters'," analysts at Barclays wrote.

Portuguese wind developer EDP Renovaveis (>> EDP Renováveis) - which has almost half of its installed capacity in North America - was the biggest loser in the Thomson Reuters Europe utilities index <.TRXFLDEUPUUTL> with a fall of more than five percent.

Analysts say U.S. production tax credits (PTC) for wind that are already awarded seem safe, but there is now more uncertainty about future government support.

"Once you secure a PTC, it is for the whole useful life of the asset and they cannot change that. Any impact of a Trump win would be on new capacity, on growth," said Banco Portugues de Investimento analyst Gonzalo Sanchez-Bordona.

Italy's Enel (>> Enel S.p.A.) and Spain's Iberdrola, (>> Iberdrola SA) were also among the top losers among EU utilities, down 3-2 percent.

Iberdrola's US unit Avangrid Renewables has more than $10 billion of operating assets totalling more than 6 gigawatts (GW) of owned and controlled wind and solar in the United States.

Enel has renewable energy projects in 21 US states with installed capacity of about 2 GW of geothermal, wind, solar and hydro. The group's total capacity is 84 GW.

A Milan-based trader said Trump, a climate change sceptic, may intend to push production of fossil fuels and revive the struggling U.S. coal industry, at the expense of renewables.

Danish wind farm developer, DONG Energy, (>> Dong Energy A/S) whose current assets and construction projects are solely in Northwestern Europe, but who has secured development rights for a potential 1,000 megawatt offshore wind farm off the U.S. east coast, saw its shares drop as much as 4 percent.

"Since decisions on offshore wind are made on a state-level, we do not expect the presidential election to affect these opportunities," Dong CFO Marianne Wiinholt told Reuters.

German's E.ON (>> E.ON SE), whose shares fell 1 percent, said it will keep expanding its U.S. renewable business, adding it was too early to assess the impact of Trump's win.

Eighty percent of E.ON's renewable energy investment pipe1line is in the U.S., where it hopes to build 3 GW of onshore wind and 1 GW of utility-scale solar.

Shares in Finnish refiner and renewable diesel maker Neste Oyj (>> Neste Oyj) fell 6.2 percent on the back of a weakened U.S. dollar and fears that Trump would change rules on biofuel tax breaks in the U.S.

(Additional reporting by Stephen Jewkes in Milan and Geert De Clercq in Paris; Writing by Geert De Clercq; Editing by Maria Sheahan and Louise Heavens)

By Nikolaj Skydsgaard and Christoph Steitz