I'm working on single axis solar tracker project. Solar panels will towards the sun with maximum angle from sunrise to sunset. the panel direction is east-west or near east-west. I need to make angle formula that can give optimum angle in a day between sun and panel. I'm using NREL solar position algorithm document to calculate angles. I don't understand how to formulate tilt angle. İf i choose direction east-west, can I use directly hour angle for tilt angle? Is it enough to calculate tilt angle using zenith and azimuth angle?
The solar azimuth angle is the "bearing" of the sun, it will change from East to West each day.
The solar zenith angle is the angle between the vertical direction and the sun. It will change from 90 degrees at sunrise, to a minimum at midday, and then increase again to 90 at sunset.
Your system can only tilt to correct for the change in solar zenith angle. So you tilt the panel so its angle with the ground is the zenith angle.
/ angle with ground = zenith angle of sun
Now, when the sun isn't due south, it's not possible to get 90 degrees. But tilting the panel to that angle is close to the best that you can do, except when the sun is very low in the sky. But you optimise for when the sun is high, since this is when you get the most intense light.
Better results can be had by swivelling East and West, since at the critical times around midday, most of the sun's motion is East-to-West. According to the source by swivelling East-West in a one-axis motion, you can get 20% more power from the panel, compared to a fixed panel. Tilting up-down will get less (my source didn't mention a number)