Milliwatt: Cheap choices about energy

I finally decided to recharge my electric lawn mower with solar power (despite the long payback, as discussed in a previous post).

I bought two, 12 V, 5 W, amorphous cell panels, and a 12 V/24 V charge controller (the mower is 24 V). This will provide plenty of trickle charge to keep the batteries from degrading over winter, and enough power to recharge within a week in the summer (even with the mower and panels parked in a marginally sunny spot). The panels and charge controller have a quick disconnect so that all that stuff doesn’t need to be hauled around while mowing (and potentially damaged). It also freed up about 6 sq.ft. in the garage (should I count that in the ecological benefit?).