Shed Dormer - Passive Solar Overhang for Summer Shade and Winter Sunlight

While working with an architect on the design of a home addition, we decided on a south-facing shed dormer for the second story. Given the shed style, I mentioned I wanted the overhang of the roof to let winter sun in, but shade out most of the summer sun.

Because I'm a fairly hands-on guy, and my architect (great guy) had not designed such a thing before, I went online and found the following helpful bits of info. But it took a lot longer to find it all, so I thought I would post it here for you, my loyal and devoted readers:

With the equation to the right, you should have most of what you need to calculate how much overhang you need. Two of the variables ("S" and "W") require you to know where you are going to build. If you don't know that, then you need more help than I can give.

Go here to calculate S and W. If I'm thinking correctly, the two dates you need to use are the Summer and Winter Solstices, June 21 and December 21, for S and W respectively.