I want to make sure I'm doing this right. Can anyone confirm?
I entered my zipcode (04220) at this link to get my decimal degrees latitude and longitude
http://www.ngdc.noaa.gov/geomagmodels/Declination.jsp (http://www.ngdc.noaa.gov/geomagmodels/Declination.jsp)
Then I copied those values over to this calculator to get the degrees minutes seconds interpretation of lat/long
http://www.fcc.gov/mb/audio/bickel/DDDMMSS-decimal.html (http://www.fcc.gov/mb/audio/bickel/DDDMMSS-decimal.html)
Then I entered them into this solar noon calculator to get the exact time that the sun is at its highest
http://www.srrb.noaa.gov/highlights/sunrise/sunrise.html (http://www.srrb.noaa.gov/highlights/sunrise/sunrise.html)
Based on this data below, my solar noon is 13:44:50
Lat: 40 deg, 17 min, 16 sec
Long: 70 deg, 22 min, 6 sec
UTC Offset: 4
DST: Yes
Date: August 20, 2008
Then I go outside and use a plumb bob braced and suspended over a flat horizontal surface at that time and record the shadows direction, correct?
How about --- drive a stick in the ground. At noon - standard time for your area, scratch a line on the ground where the sticks shadow is. That will get you a pretty well optimum angle for max solar if that is what you are interested in.
I'm sure your way done right is probably better but I'm too lazy for that.
Seems I've read that within about 15 degrees will do pretty good - nothing wrong with being exact though.
Very true, a straight plumb & leveled stick would do fine as well :)
Right, Glenn. As close as you can estimate is good enough in the real world. If you're a little to the east your morning will produce slightly more power than the afternoon, and vice versa. Sometimes you local conditions will dictate whether or not you should shift one way or the other. For example here in the Jemez during July and part of August the clouds start building in the afternoon, so it may be advantageous to turn the panels slightly east of true south. Then again MTL, it doesn't matter all that much as the hours of summer sun are longer than the winter time and most users would be advised to optimize their system for wintertime hours.
There are many compromises and I don't feel it's critical enough to sweat the fine points. OMMV.
Possibly changing the angle to the horizon might be of more value, when looking at summer vs. winter. ???
How about this idea.
Go back to your first website, enter your zipcode and todays date and hit the button "compute declination". It will tell you that your declination is 16 degrees 11 minutes west. That means that "true north" is 16 minutes 11 minutes to the RIGHT of magnetic north.
Get yourself a compass, let it show you where magnetic north is (magnetic south is the opposite direction). Go 16 degrees to the right of magnetic south. That is "true south" for your location, accurate to within a degree.
Let us know what you choose to do.