Is safety harness the only solution for fall from height?

Good day sir! Safety Harness is one of the solution for fall protection but it is not the ONLY option. You can also put temporary structures such as scaffolding and platforms that can support you from working at heights. 

PPE is always the last solution, trying engineering controls such as working platforms, framework supports, design changes to have guard rails installed, etc.

even on scaffolding above1.5m a harness should be worn 

well as a rule regarding working at height, to maintain full prevention both primary (platform guarded structure, MEWP, Scaffold, etc ) and secondary fall protection devices (full body harness) should be in place and used , sometimes if the is edge protection is strong enough and well constructed full body harness is useless , however its better to be used as the last line of defense, over all if someone is not aware of the proper using of harness, it would kill him and it would make his status worst of he fall down.