Green energy is unsustainable as a business unless the government starts investing heavily in new technology, it has been claimed.
According to a poll by the Renewable Energy Association (REA), 32 out of 39 members said they were suffering from a shortage of cash and other problems related to funding.
Philip Wolfe, director general of the REA, said: "Given all the rhetoric on 'Green New Deal' and 'Green Tech' it is astonishing that so far the renewables industry has received no dedicated support even in areas that don't cost extra money."
He claimed that many of Britain's green energy companies are struggling to gain access to investment and competitive rate loans.
Last month, the government scrapped its solar energy grant scheme.
Campaigners claimed the decision to end because of unprecedented demand made a mockery of its commitment to building a green economy, reducing carbon emissions and tackling climate change.
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