Anybody controlling lights with photocell?

[Ray]

Originally Posted by estación seca

Small screw-in-socket devices exist for porch lights. I'm not sure how you could adapt one to a terrarium some distance away.

They switch the power just the opposite of the OP's request - on at dusk, off at dawn, rather than matching the sun's normal light/dark cycle.

Like you, I think Joe is overthinking it. Using a simple timer to set on/off hours is sufficient, adjusting it twice a year for different day lengths is sufficient, if necessary at all.