When I first started this project, I began by building my own solar panels. However I have since discovered you can get Grade B solar panels for less than I can build them, and they are just as good as Grade A solar panels, other than they may not look as nice.
Here are some similar to what I purchased. They are currently $0.80 per watt I just found some here for $0.72 per watt with free shiping!! (I paid $1.00 per watt for mine). I like getting the 60 cell panels, because they will work with the new micro inverters, as well as standard inverters.
You do want to make sure you have solar panels that match your inverter. If you plan on using micro inverters, then you will just need to us a 60 cell panel to match your inverter. If you plan on using a single inverter (like I used), make sure your voltage will fall in the range of the inverter. I actually had to add more panels than I had originally planed because my panels were on the low end of the voltage, and my inverter would shut off when the voltage would drop too much. Also the inverters efficiency is higher when you are in the higher end of the voltage. My inverter is rated at only 1.8 KW, but I had to put up 2.25 KW (10 panels at 29v = 290v when run in series, my inverter is rated for 200 to 600 v) worth of panels to get my voltage correct. If I were to do it again, I would get a 3 kw inverter, and tun about 12 panels on it. It is ok to run more watts like I did, but at peak power output, my inverter will just max out, and not use all the power the panels can produce.