For those who are new to solar panel making or if you don't have an engineering background, here is our recommendation:

http://cgi.ebay.com/500-3x6-Untabbed-Grade-A-Solar-Cells-Only-for-Panels_W0QQitemZ130359804215QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item1e5a0cc137

V. Panel configuration:

For those who are new to solar panel making or if you don't have an engineering background, here is our recommendation:

1) Make small panels first so you gain experience.

2) In most situations, make either 36 or 72 cell panels, and connect them in series. 36 cells give you 17.5 or around 18 volts or so. And 72 cells doubles that. These panels are very useful, and you will find a lot of matching products that will want to buy! For example, you almost always want to use a charge controller if you make your panels to charge batteries. Charge controllers usually come in 12 or 24 volt settings, which match your panels' 18 and 36 volts very nicely. Yes, your panel voltage should be 1.5 times the voltage of the battery you intend to charge. Connect more panels together if you want to tie to the grid, in which case, always use an inverter.

3) For a lot higher voltage panels and configurations, consult a professional. Just don't fry yourself.