Solar panel companies typically settle on good enough. Given how costly it is to make solar panels that automatically track the sun, most are fixed in one direction (a south facing roof, for example) and stay there to maximize exposure.
But, if you were feeling crazy, you could build a massive rotating glass sphere filled with water that directs sunlight to the precise point where the sun’s energy can be collected most efficiently. That’s the inspiration behind the beautiful creations of architect André Broessel. His ball lenses, either solid glass or water-filled, reportedly attain 35% higher efficiencies than conventional solar panels without such lenses. These "fully rotational weatherproof natural optical tracking devices" can concentrate diffuse daylight (or even moonlight!) at most latitudes.
Beautiful, but perhaps entirely impractical. For the wall-sized version, the weight is staggering. The volume of a 2-meter-diameter glass sphere filled with water--check our math: (1^3*(4/3)*3.14), multiplied by the density of water (958 kg/m3)--suggests you’ve got a 4-ton lens on your hands. Compared to friendly, but less efficient, PV panels at 5 to 10 pounds per square foot, it’s a beautiful architectural concept that won’t see the light of day without creative cost-benefit analyses and some really strong wall-mounts.
But beauty, of course, is priceless. And these gorgeous glass spheres will light up any home, before pulling the walls down around you.