Hi there!
So I was testing your mod in a creative gamesave with permanent day and your solar panels shut off from time to time. From looking at the code, you predefined the days start and end depending on ticks right? Two problems there.
1. As I already stated if someone shuts off night times
and
2. If someone modifies the daytimes (e.g. DayNightExtender)

My advice would be to determine the days stages with surface[1].darkness since it would be more dymanical that way.

Cheers!

This should be fixed with version 1.0.1.

Using "surface.darkness" does not work because the script "refuels" all panels once per day for performance reasons. The fuel amount is calculated to last for the remaining day.

I changed the refueling logic to use "surface.dawn", "surface.dusk", "surface.evening", "surface.morning", "surface.ticks_per_day" and "surface.always_day" to adjust the amount of fuel as needed.

Hey there.
The problem still persists. Since you also designed a mod for changing day/night times, I suppose you realized that some other mods changing times use logics which collide with your own logic. I would really recommend you to take the way of evaluating .darkness since it's a read-only variable and doesn't depend on when dawn, dusk, night and morning are. I also noticed that your panels use an on/off mechanic which could also be solved by .darkness. (Observation made with your mod only btw.)

Cheers!