Yes it's ruinous just for the light, unless you live in an underground bunker ...
But if you use light in large quantities not to light but to heat something, it's much more fun.
You keep your openings, windows, bay windows ... for your light comfort and possibly to heat your home. But to have additional heating, you conduct the light from this sensor (located where you want, even far from the home because the line losses are low, which differs from a usual solar thermal collector) and you distribute it where you want.
For example, you put a sensor on the roof, on your fence or at the bottom of the garden ... and you lead the concentrated light into a domestic water tank that will be heated, or even in a simple box anywhere in the house and this box will heat up!
It is then enough to create a receiver which accumulates this heat (the box contains a mass, a soapstone plate ...) and which returns it during the night.
In this case the light introduced into the habitat is no longer superfluous and surely less ruinous ...
