The problem is that the Sun constantly moves in relation to the stationary PV module. Actually, the apparent motion of the Sun is due to the Earth's motion, but for our purpose here this celestial fact is mere trivia. Even if we place a module so that is perpendicular to the Sun at solar noon, it is not even close to perpendicular in the morning and evening. This daily east to west solar motion is called solar azimuth. Also consider that the Sun's apparent height in the sky changes from winter to summer. This yearly north to south solar motion is called solar declination. And you thought solar power was simple. Well, it really is...

Actually you can face a PV module south, tilt it so the included angle between its face and the ground is your latitude, and you're done. It will work and it will work well. What we are talking about here is squeezing anywhere from 10% to 40% more power from PV modules by keeping them as perpendicular as possible to the incoming sunlight.

An Angular Matter

It's matter of angles. If the module is to be kept perpendicular to the sun's daily east to west motion (azimuth), then a device called a tracker is used. A tracker follows the sun's daily motion and provides anywhere from 25% to 35% more power from the PVs hitchhiking on its back.

If you keep up with the sun's seasonal north to south migration, then manual adjustment boosts PV power production by up to 10%. The chart on the next page has all the data necessary to accomplish this seasonal, north/south, adjustment.

Cosine Stuff

While using PV modules is very simple, the mathematics describing their angular relationship to the sun are very difficult. I sought help from Sam Coleman who is adept at ritual trigonometry. After covering

Solar Declination up A

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

Get My Free Ebook

Post a comment