You're still off by a power of ten in the areas: 10x10cm = 0.01 m2. (Edit: by the way, I think you also plugged in the sphere volume formula - surface is 4.pi.r

You're still off by a power of ten in the areas: 10x10cm = 0.01 m2. (Edit: by the way, I think you also plugged in the sphere volume formula - surface is 4.pi.r²). Radius of one meter is a bit close - make that three, and you're off by another order of magnitude - 10 uW harvestable.