The 52% versus 48% decision “raises serious questions for investor certainty, energy security and much needed investment in the UK energy infrastructure” said UK industry body The Renewable Energy Association, which was among the first to react to the result.

It added: “The vast majority of our members had fears of Brexit, and we will be consulting with them and government in the coming weeks to set out a plan for continued low carbon energy investment, deployment and assurance of the 117,000 jobs in this sector.”

German industrial giant Siemens, which was vocal in the run-up to the vote with its fears over the impact of an exit on its new £310m ($349m), 1,000-employee offshore wind hub in Hull, northeast England, today said "this was a decision for the British people and their view must be respected", adding that it "remains committed" to its business in the UK.

Siemens said in a statement sent to Recharge: "As a global business with significant, long-term investments in the UK and high local value creation, Siemens is not so much exposed to negative effects that we might see.

"Nevertheless, the government must now move swiftly to unify and agree the nature of the UK’s relationship with the EU and other trading partners, creating clear roadmaps to encourage future investment."

The CEO of industry group RenewableUK, Hugh McNeal, earlier this week attempted to calm nerves ahead of the vote claiming the offshore wind sector has a bright future regardless of the outcome.

Today McNeal said: “As a trade association, RenewableUK has a wide range of member companies with differing views on the result of the EU referendum.

"Our focus will continue to be on delivering power to the UK at the lowest cost. Our future is bright; the European and global opportunities remain immense for the industries I’m proud to represent.”

UK-based utility SSE, a major onshore wind operator which recently took a final investment decision to build the 588MW Beatrice offshore project, told its investors this morning: "It is not yet clear how this matter will now progress, but SSE believes that the UK government should be mindful of the importance that the harmonisation of the GB energy market with the countries in Europe can have on efforts to deliver clean, secure and affordable energy."

Germany's E.ON, another key investor in UK renewables, said: “The UK EU referendum was always a matter solely for the voters and they have now spoken. It is expected there will now be a period of negotiation led by the UK government."

Tony Ward, head of power and utilities at business services group EY, said the leave vote will "likely make its impact felt by creating an immediate heightened level of policy and regulatory uncertainty.

"Whatever government emerges in the aftermath of the leave vote it will need to clarify its policies with respect to climate change, renewable energy, technology preferences, State Aid and many other matters of direct relevance to the utility industry, and to its investors."

Ward added: “In many respects, the UK has taken a lead in Europe when it comes to renewable and low carbon policies – the question as to whether support for low carbon technologies will be withdrawn, and whether other industries will be favoured, is a fundamental one.

"How UK governments from now use their freedom from EU policy constraints will be watched closely.”

An early casualty of the verdict was Cameron, who campaigned to keep the UK inside the EU but this morning said he plans to step down by October. The UK now faces a two-year process to extract itself from the 28-nation bloc.

A so-called Brexit will have profound implications for UK clean-energy goals – currently enmeshed in EU targets – and its world-leading offshore wind sector, which is largely driven by investments from European power majors.

The run-up to yesterday’s referendum saw warnings that the UK’s interests would be best-served by remaining inside the bloc.

Former UK energy secretary Ed Davey told Recharge: "It's difficult to see how British renewables would prosper more outside of the EU."

An early indication of the uncertainty set to dog UK energy policy in relation to the rest of Europe came earlier this month, when the country declined to immediately sign an MoU with other nations over offshore wind and grid co-operation.