Living in a sunny place like Arizona has obvious advantages when it comes to living off-grid, including the potential for solar electrical generation. Two crucial components of getting the most out of a solar panel are
- Proper orientation for the location and season
- Storing unused power for nights and cloudy days
We’ve put a lot of thought and effort into solving the first of these, which involves research into the facts about our planet’s dance with the Sun. We won’t try to school you on the many particulars of solar dynamics, and instead will take you right to the core problem: during a particular day or season, what is the angle between the southern horizon and the sun? There is no one answer to this question until you’ve identified where on earth you are standing.
In our research, we found a Table of the Declination of the Sun that tells us the angle that the Sun makes with the equator for the average day in a four-year (leap year) cycle. In order to find the angle here on a particular day, we had to do a little arithmetic with angles and such, and it’s pretty mind-numbing. So instead of formulas and arithmetic problems, we give you a tool for calculating and visualizing the angle between the Sun at midday and your horizon. Please note that this tool was written for, and tested on, Mozilla Firefox (version 3.6). Firefox is free to download and a very useful browser, so if you are using another web browser, you’ll probably want to use Firefox to get the use of this tool.
Once you know the range of angles that the Sun will sweep out overhead at your location during the course of the year, you are ready to set up your panels. The manufactured brackets sold for our panels were very expensive; we save hundreds of dollars on our three brackets by buying 2″ angle-iron and drilling the holes ourselves. (Two pointers on drilling in metal: slow drill speed, and adding oil between the bit and the work piece. Okay, one more: use a drill press, not a hand drill).
Don’t assume that any bracket will do, or that the one we made will work well in your location. For example, look at the angles for the Equator (see illustration): our bracket design would be impractical there, as it would in a very northern latitude. Once you know where the Sun will be overhead during the seasons, you are on your way to setting your panels in the best light.
Finding the right hole positions is easier with a little bit of mathematics involving the Law of Cosines, but that’s not really great reading for most folks. If you have any questions about this, feel free to contact us. In the meantime, we try to adjust our panels to within 12 degrees of the perpendicular sun rays, although in the hot months some literature suggests increasing the angle of the sun to the panels to keep the temperature lower on the panels.
Another important consideration is finding solar South. A magnetic compass points only roughly north, missing the polar axis by 12-14 degrees. Things like underground rivers and mineral formations under pressure can cause local deviations in the magnetic field, so use a compass with informed caution on solar project alignments.
The most reliable method is to use the night-time. The North Star, Polaris, is pointed to directly by our poles. To find it, locate the Big Dipper. On the side of the cup opposite the handle, the two stars on the edge of that constellation point directly to the North Star, and that is your best guide to solar North. South is the opposite direction (heh).
Keep in mind that the Big Dipper moves (appears to us to move), like all the other constellations, in a circle around Polaris, so it likely won’t be oriented to match the illustration. Just once every 24 hours will the stars look like the picture.