I've been toying with the Dyson-swarm concept for a while, and specifically a tale about how it might be built. Let's say that it's Australia who build it, being a reasonably developed group with a history of resource-extraction and solar exposure. However, the problem I'm facing is this:
It's a death ray
So, assuming that they have the handwaved ability to retrieve about Kardashev-I of power from our local star, to be delivered in convenient wavelengths to a point of their choosing above the atmosphere, in a direction they so choose ... could the "Australian Department of Power" persuade the rest of the planet that they planned to put it to uses that wouldn't bother them? (Or preferably actively benefit them?)
There are three concepts I'd considered, and two very good reasons not to build it:
End winter. This would take less than 50% of the power available, but is it a good idea? Probably not.
Lead cyclones away. They're a problem, but with this much power available, it's possible to heat the ocean "slightly" in a path out to sea. You can also divert hurricanes, if you allow for the Coriolis effect. Of course, you could lead them back if someone annoyed you...
Carve vast channels to the interior of the continent. There's a lot of desert here, it would be nice to have some more water. This question wanted to do the same thing, but didn't have the budget to build mountains.
Cooling will be a problem. Forget the greenhouse effect, this can up to double the incoming power. Assuming blackbody radiation, the planet would heat to an average of about 56 C, if we beamed down all the power.
Politics means that someone, somewhere, will have this notion that the contraption can ('should') be used to make life difficult. 'And if we can't have it, nobody should.' It does make for a nice way around anti-nuclear treaties, though.
Supposing all of this, and that the intentions of the builders are legitimately peaceful (perhaps they've almost invented the universal constructor, and just want to power it), how could they get away with having it, without having to weaponise it?
Secrecy is not an option. I've put the controllers in Australia partly to avoid giving it to a current world-power, and partly to put quite a bit of land-area in the way of sabotage. You can assume that it's "perfectly secure" from an IT perspective.
Control is done through standard satellite communications, (and some big coloured flags laid on the ground in patterns, if required) and there can be protocols to act as a dead-man switch.
Fragility is the standard space-device one: very easy to destroy, beware of debris. It's possible it might melt a nuke before it arrived, but a railgun doesn't care if the projectile is molten/gaseous on arrival.
Time is much-like-the-present, where the whole system is coming online now, but hasn't been noticed yet. Most of it is mirrors which are hard to spot if they're not reflecting sunlight toward you. Let's say that the builders kept it secret because nobody took it seriously, and the later budget never made it look significant - more of a white-elephant.
(I suspect there are many better ways to ask this. Thank you for feedback on that, too.)
Edit: The answers so far are good, but focus on what it can be used for instead. What I'm looking for is how to persuade other governments not to treat it as they would a rogue-nuclear-state. The builders will wish to avoid diplomatic problems caused by their new industrial facility.