From Long Island to the Arizona desert, developers are covering their lots with canopies of solar panels. Lot owners get to double up on their use of underutilized land and to offset their utility bills at the same time. And very little stands between most lots and the sun, so they can produce plenty of power. What's more, the canopies provide shade when it's hot and prevent snow from accumulating in the winter. Some have charging stations for electric vehicles.