I've toyed with getting a solar system for awhile now, more so recently with the addition of federal tax credits. I still haven't found a way for it to be economically worthwhile for me. Remember that you shouldn't just be looking at the return of your investment. You should compare your investment in a solar system to what you would have earned with your money if you had let it stay invested. Here's a link to a BP's Solar Economic Estimation calculator that I've found useful for coming to my conclusions -
link.