[RedDevil]

Beware - I read more than once that using mirrors to boost PV panel output voids their warranty. And if you have the space to put them down, just adding PV panels equal to the cost of the mirror system may boost the output just as much.

I had another idea, which is to use powered mirrors to reflect sunlight (and infrared) towards your windows as a means of heating your house in winter. I do not know how effective PV panels mirror IR, but if they do it could be double efficient that way.

The downside is extra light in your house, and of course it does little at night or when overcast (although IR penetrates clouds better than visible light does, so some heat will find its way). Also, the most effective setup would be north of your house (in the northern hemisphere, or south down under) where there probably aren't big windows.