The buildings southern aspect should face as close to Solar South as possible, and all solar panels and solar water heaters should also face Solar South...but where is Solar South?

Solar South, Map South, Magnetic South and True South are all slightly different. Solar South is the direction of the Sun at its highest point in the sky on any day. This is literally mid-day but since time zones encompass wide areas it is not forcibly at noon.

The diagram to the right shows sun paths for Flagstaff Arizona. The lower line shows the winter sun rising at 07:32 at an angle of 60deg. East of Solar South. ( For a fuller explanation of the Diagram see Sun Path )

At 12:00 it is 31deg above the horizon but has not yet reached its zenith. So to find at what time the sun reaches it Zenith I tracked shadow lengths at Sedona, which is the same longitude as Flagstaff.

The graph to the left show shadow lengths against time on June 21st, the summer solstice.  ( You can do this on any day, just happened I chose this one)

The suns zenith was reached at 12:25.  Sedona has a longitude of 111deg 46min.  where as White Horse Mesa is to the East at a longitude of 109deg 10 min a difference of 2deg 36min.

The sun traverses 15deg every hour, or 5deg in 20mins. So 2deg 36min, say 2.5 degs takes 10 mins. So the zenith of the sun at White Horse Mesa would happen at 12:15.

So now when we are on site at 12:15 the sun will be at the Solar South and house and solar equipment can be optimally positioned.