I think mirrors are incredibly underrated by people theorizing about future space technology.
On Earth a mirror has to be heavily constructed to holds its form, in space with little or no gravity and no wind to contend with they can be as lightweight as soap bubbles.
The lightest mirrors that are now being studied are intended as solar sails, 3 grams a square meter has been achieved, if we round that down to 1 gram a square meter, how much light can be collected by 10 tonnes of mirrored material at various distances from the sun?
Well, 10 tonnes, at 1 gram a square meter, would give you an area of 10 square kilometers:
10_________0.013__________130.0 (Saturn approx)
So even at the distance of Pluto, just 10 tonnes of mirrored material gives us the ability to concentrate 8 megawatts of sunlight, if solar cells will give you 1KW/KG at Earths distance from the sun, using light-weight mirrors to concentrate the sunlight, they'll still give you about 0.44KW/KG even at Pluto's distance from the Sun.