Energy Bookstore

Mark C. Robinson
The Energy Grid
14 Veterans Rd, #22
Amherst, NH 03031
(603) 413-0322

To get the most from position-fixed (or seasonally adjusted) photovoltaic or thermal solar panels, you need to point them in the direction that captures the most sun.

Solar panels should always face true south in the Northern Hemisphere, North in the Southern Hemisphere, tilted from the hoizontal at a degree equal to your latitude plus 15 degrees in winter, or minus 15 degrees in summer.

An additional 3 - 5%, though, can be gained by evaluating this more carefully.

Winter

The winter season has the least sun, so you want to make the most of it. The tilt should be designed so that the panel points directly at the sun at noon. To calculate, multiply your latitude by 0.9, and add 30 degrees.

For example: New York is at 40 degrees. 40 X .9 + 30 = 66 degrees tilt from horizontal.

See below for a list of cities and their latitudes.

Solar Seasons

Many systems allow for a manual adjustment. Adjustments should be made around
March 1, April 19, August 23, and October 14th for the Northern hemisphere, half year later for the southern hemispehere.

Tilt angle: spring and autumn - latitude minus 2.5°.
Tilt angle for summer - 52.5° less than the winter angle.

These recommendations are based on sea level with an unobstructed view of the sky. At altitude, lowering the angle of tilt by a few degrees will capture more sunlight when the sun is lower in the sky. Thinner atmospehere will permit a better harvest of sunlight.