Cole Mechanical Services employee Geoffrey Hatton and his colleague were dismantling a compactor at a site in Wilmslow, Cheshire on 19 January last year, Minshull Street Crown Court was told.
As the workers were removing cladding from the machine's frame, a large piece of cladding came into contact with the MEWP, causing it to fall over.
Hatton fractured his skull and two ribs, spent two months in hospital and has been unable to return to work.
An investigation by the Health and Safety Executive (HSE) found the workers should not have been using the MEWP outside as it was only suitable for internal work. It said Cole Mechanical Services had not trained its staff in how to use MEWPs and had no risk assessment for the work that was being carried out.
The executive also found that another employee had been working on a fragile roof with no edge protection at the time of the accident.
Cole Mechanical Services, which supplies, services and maintains waste compactors, balers, scissor lifts, dock levellers and floor care equipment, pleaded guilty to breaching s 2(1) of the Health and Safety at Work Act and was fined £30,000. It must also pay costs of £8,995.