Space based solar power.

Ideally, you would point it at Earth and sell solar energy. Or point it at a solar panel to convert it to microwave frequency as beam that at a receiver on Earth to sell electricity.

Probably not visible to people. Depends how you build it, but for maximum efficiency you will be using a very tightly focussed beam.

Just like your laser pointer is making light using a LED, you can also have a visible light laser. You can only see the laser pointer side on if it passes through some particular like smoke, that bounce the light towards your eyes.