Trollh�ttan was founded by the river G�ta �lv, at the location of Trollh�ttan Falls. The site was first mentioned in literature from 1413. For centuries, Trollh�ttan was an obstacle for the boats travelling the river, up until a lock system was completed in the 19th century. It has since been updated several times and the present locks were finished in 1916.
In the late 19th century, hydro power was developed in Trollh�ttan. The Swedish energy corporation Vattenfall ("waterfall") took its name from the falls in Trollh�ttan. Today the city has two operational hydro power stations, Olidan and H�jum. The hydropower has helped the city in its industrial revolution.
Trollh�ttan wasn't granted city rights (which today have no legal effect, but is purely historical) in 1816 at which time it had about 15,000 inhabitants, now grown to 54,000
