An investment in hydro power means an investment in a long-lasting asset. The trading of its produced electricity has to respect the laws of physics: Electricity cannot be stored to a larger extent, production and demand need to be in balance at any time. Long-lasting assets as hydro power plants – some are more than 100 years old – require therefore a corresponding maintenance strategy.
A new turbine runner can be a profitable investment. But efficiencies and payback periods need to be evaluated.
By the way: Institutional investors are more and more interested in hydro power due to its longevity.