10 Watt solar panel mounting bracket.

[mklotz]

When I was a kid I built a solar tracker for a grade school science show. It was intended to be an electromechanical sundial but I never finished it.

Imagine two small solar cells separated by an opaque vane (mine was made from tin can metal). This assembly sits on a platform capable of rotating about a vertical axis. A small DC motor can drive the rotating platform via a friction drive. The output from the solar cells power the motor and make the platform rotate.

When the vane is pointing at the sun, the cells are illuminated equally and no net power is delivered to the motor. When the vane is not pointing at the sun, one cell is generating more power than the other and the motor drives the assembly until both cells are illuminated equally.

My device is long gone but a net search turns up this version...

Much more sophisticated construction than mine but the concept is exactly the same. Add a scale around the base and a pointer on the table and you have a sundial to tell the time with no complex geometry to lay out the calibrations.

No "steenkin' computers" needed.