Does Panel Orientation Matter?

Honestly, I am pretty surprised by the lack of information out there about this subject; The majority of information I did find was either misleading or wildly inaccurate.

The short answer to this question is, YES, they do matter. But, how much?

According to this article, titled, "Does Tilt Angle or Orientation of Your Solar Panels Matter?", orientation doesn't matter much at all. The article claims that the Sandia National Laboratories (one of the foremost labs on photovoltaics in the country that considers renewable energy a matter of national security, read: very credible) says...