As alluded to in the last post, orienting the solar collector to true south is necessary to get the maximum energy from the panel. There are several ways to do this, they are:

1. Use a magnetic compass, and calculate the magnetic declination into the compass azimuth
2. Use a topographical map, and site along a line to a known land mark
3. Use a solar noon calculator, then at solar noon, note the sun’s shadow on the ground.

The fastest way seems to be using a magnetic compass. I looked up the magnetic declination (the variation between magnetic north and true north) for my area on the NOAA web site. This site is easy to use, you just need to know your zip code. For my area, the declination is 13 degrees west of north, in other words, my N compass needle should be pointing at 347 degrees and the compass will be aligned on the true north/south axis. I don’t trust magnetic compasses that much as they are influenced by metal objects and electrical fields that are nearby.

To find true south using a topographical map, you have to be able to interpret the map, then find some land mark that is due south from your mounting location and use it to align your solar collectors. This method should be backed up by one of the other methods described here. To find topo maps, use www.topozone.com. They have the maps right on line, you just enter your place name and hit search and you should have a map of your area. I always resize the map to large and 1:25:000 aspect ratio. It may be necessary to pan around and find your house. Once the house has been found, click on the location to center the map on it. This will also give you the coordinates for your house. You should change the latitude and longitude coordinates to D/M/S format and write them down.

Finally, you can use solar noon to show you where true south is. Basically, solar noon is when the sun is at its highest point. In the northern hemisphere, that means the sun is located due south, and vice versa in the southern hemisphere. To use the solar noon method, you need to have two stakes and a piece of string. Drive the first stake into the ground at your panel mounting location and tie the string to it. Tie the string to the second stake as well. At the time of solar noon, align the string with the shadow of the stake first stake that was driven into the ground, and drive the second stake into the ground. The string is now along the north-south axis. You have to know the exact time of solar noon at your location. To find this information, I again referred to the NOAA website. You can either use the closest city in the drop down list, or enter your latitude and longitude from the topo map. If you do not know how to read a topo map as described above, you can find the reference coordinates for your community at the FCC website using place name and state, or at the US Census website using zip code lookup

For my site, I used methods two and three. This is the north-south axis at the mounting location for my solar panels.

That agrees within about a degree of what I extrapolated from the topographical map. This is another picture with a square aligned with the big side along the north-south axis, and the small side along the east-west axis.

Basically, the face of the solar panels will be aligned along the east-west axis. Incidentally, the magnetic compass was way off.

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