You should look at
www.sunpowercorp.com
Sunpower manufactures the most efficient consumer panels at this moment. The SPR-315 solar panel is ~22% efficient. The A-300 solar cell used to be the mainstay of solar car teams and they were only ~20% efficient. For comparison, the average solar cell efficiency is ~12-18%.
Sunpower makes roof tile versions, but I bet they are more expensive than normal panels. You'll get the biggest bang for your buck if your mount your installation on a solar tracker. Putting panels on your roof is like taking 4 gears out of your car's transmission...efficiency is severely affected.
Expect to pay ~$8000/kWh without subsidies. What the panels lack in price they make up for in efficiency (i.e. even though each panel costs more, you'll need less).
Without some sort of up-and-coming nano-technology, there is no way flexible film solar cells will meet the efficiency of Gallium Arsenide panels. The only technology likely to take Sunpower's throne away is concentrated light solar cells which have shown efficiencies of ~40% in the laboratory.
- LostCause