In order to mechanize and make the design so robust that a blacksmith with the minimal tools can make and maintain the solar tracker we are searching for ways to construct a mechanical solar tracker.
The rotation of the earth is 15 degrees per hour and while the time at which the sun is highest in the sky may vary(1) with the place of the earth in relation to the sun, the rotation doesn’t. A speed adjustable clock mechanism that in the morning is fixed on the sun is sufficient. A target behind a hole in a plate for the sun to shine on can give an indication if the clock is running on time and pointed directly to the sun.
If there is a need for tracking the sun up and down during the day an adjustable circular guide is in principle sufficient. With a Heliostat that reflects on a stationary target the movement of the mirrors becomes effectively half the movement of the sun through the sky. 90 degrees from east to west and from vertical to 45 degrees up and down.
What do we need to move a heliostat during the day.
Every day the heliostat can be reset and wind-up again.
An escapement with gears to regulate the speed at which the heliostat can been moved.
A weight to provide the energy for the mechanism to run on.
A way to unlock the gears so the heliostat can moved freely.
In the meantime nothing prevents us from using solar power for electrical steering.
(1) The variation in sun-time during the year, when you calculate the position of the sun based on time, you have to take into account where the sun is based on the position of the earth in her orbit around the sun. When you mechanical set the clock by pointing it to the sun that problem disappears.