More than half of US states offer serious rebates and/or tax breaks for home solar arrays.
For example:
"Clark Beebe, 57, of Springfield, N.J., bought a $50,000 solar power system two years ago for $15,000 after rebates, installing it on the roof of his four-bedroom house. Because he offsets what he uses with what he pumps into the grid, his annual power bill has dropped from $1,270 to $170, though he also installed energy-saving appliances. His $1,100 yearly savings is supplemented by $500 in clean energy credits, cutting the payback period for his system to nine years. After that, he'll effectively net at least a $200-a-year profit."