If a man fell from a roof while consulting for a satellite installation job, who is responsible for his medical bills?

It depends on the circumstances:

1) If he is an employee (not independent contractor) of the satellite company, the injury may be covered by that company's worker's comp.

2) If he is an employee of some other company, that company's worker's compensation may cover.

Worker's compensation pays for injuries caused on the job. Not all workers have worker's compensation, however. For example, many freelancers or independent contractors do not have worker's compensation. If there's no worker's comp, then person would have to hope someone--other than himself--was at fault.

3) If the fall was caused by some fault of the homeowner--e.g. the roof was not maintained properly--then the homeowner (or the homeowner's insurance) may be liable to pay.

4) If the fall was caused by the company hiring the worker (e.g. as an independent contractor) to consult, and that company was somehow at fault (e.g. gave him inadequate safety equipment; sent him up to an obviously dangerous roof), then the company hiring him may be liable.

The important thing is, if the person is not covered by workers' compensation, there must be fault--either deliberate wrongdoing or unreasonable carelessness--for him to recover compensation. Without fault on the part of another, there is no recovery; not every injury entitles someoene to compesation. So if this person was an independent contractor (no worker's comp) and either was himself at fault or was the victim of an "act of god'--something beyond human control, like an unexpected gust of wind--then no one but him his responsible  for his medical bills.