At an earlier hearing Norwich-based Durrant Electrical and Mechanical Ltd, trading as Green Home Energy Solutions, had admitted a single charge of breaching working at height regulations on September 26, 2013.

Today Recorder Oliver Sells QC, sitting at King's Lynn Crown Court, heard the accident happened when employee Chris Eldon was measuring up an asbestos roof on a tractor shed at Woodland Farm, near Watton, without using crawling boards.

Klentiana Mahmutaj, prosecuting for the Health and Safety Executive (HSE), said Mr Eldon suffered severe concussion, a fractured wrist and bruising to the base of his spine when it gave way and he fell 2m to the ground.

She said an HSE investigation had found the company had carried out an inadequate risk assessment and planning for working on an inadequate roof.

She added no-one from Durrant Electrical and Mechanical had been on site to brief Mr Eldon before he and apprentice Kyll Staff had started work.

'What should have happened was for the roof to be assessed by a competent person, who would have concluded it was fragile,' she said, adding falling from a roof could often lead to death or serious injuries.

Julia Kendrick, defending the firm, said Mr Eldon had worked for the company since 2011 and had been been given training in health and safety and working at heights. She added: 'He was very experienced and he had significant training to make him aware of the risks which were inherent in the kind of work he was undertaking.

'The injured person had completed more than 100 installations. He was a supervisor on some jobs and they considered him extremely competent. Systems were in place but were not sufficiently adhered to or implemented.'

Durrant Electrical and Mechanical had had to lay off workers after a downturn in the renewables sector, the court was told. After making a £95,000 profit in 2015, it had so far lost £25,000 this year.

'They are struggling to pay their workers and stay afloat,' said Miss Kendrick. She added the company had no previous accidents or convictions.

Firms can be fined between £14,000 and £250,000 for breaches. Judge Sell ordered it to pay £14,000, with £7,000 costs.

He said: 'I've certainly not seen any evidence of serious or systemic failings to assess risks to health and safety.'

Durrent Electrical and Mechanical was given two years to pay.

After the hearing directors Kerry and Debbie Durrant, who were present in court, declined to comment.