vasquo:
It's cheaper to pay the electric company than build your own solar array.
In general, you're right. But that also depends on how you get that array and other parts (as well as what other things you do).
First and foremost - is insulation. Attic, walls - as much as practical. Then install dual or triple pane windows if you don't already have them. Then compact fluorescent and/or LED lighting. Also a timer for your heater, plus digital thermostats for your air-conditioning (and programmed appropriately). Ceiling fans. Attic venting. Etc.
Once you've done all that, then the array comes next. You need to decide where to site it. If on the roof, you might want to get a new roof first (otherwise, you'll have to take the array down when you -do- get a new roof - so spend the money on the roof now, for a 50 or more year roof so you don't have to do it again until after you're dead).
As far as the panels...to do it cheaply will take some ingenuity. You can try to build your own panels; this can actually be fairly inexpensive, but very time consuming. Basically, there are people on Ebay selling bare solar cells, and tinned "ribbon" wire to link it all together. You have to add your own wood, tempered glass, and sealant to make a complete panel.
Another way to get panels is to try (very difficult it seems) to talk to companies or other users of panels who may have to replace them from time to time. For example, you can sometimes get broken or damaged panels from construction sign companies that use them for those highway signs; every now and then someone drunk plows into such a parked sign, and the panel may be damaged, but still usable if you are willing to invest the time into repairing it. Also, cities and other governments use small to medium sized panels for other things; look around, you're likely to find panels everywhere - contact the users of those panels, and see if they will give or sell used/broken ones to you for little to nothing...
Another good way to get panels is to go to hamfests. Inevitably, you'll find people selling old panels there for fairly little. Everything from small battery charger panels, to larger ones meant for a ham shack, a rooftop, or an RV.
After you have your panels - and once you have them wired and on the roof, you will also need a solar charge controller - this is one piece you don't want to skimp out on, so do some research, and purchase it new.
For batteries - sometimes, you can get 6-volt golf-cart batteries from golf-cart repair shops for little to nothing; wired together properly for your charge controller, and with a bit of maintenance (lead-acid) - you can have a fairly inexpensive battery bank for not much money.
Finally - you'll need an inverter (and a cutover system if you are still connected to the grid) - again, here you don't want to skimp out; buy something quality for the size of your system, and have it professionally installed.
Ok - that's all a little "pie-in-the-sky" I know, and simplified somewhat - but there are ways to do solar fairly cheaply. Lot's of extra work, and certainly not a turnkey system. You might also want to look into having "solatube" sky-lights installed (some can have an LED lamp put into them to work at night as well), and perhaps even a solar hot-water heating system.