Here is my DTL part night photocontrol. These are designed to switch the load off halfway through the night. They would be useful anywhere lights do not need to be on all night. Or for applications other than lighting!
The only thing about these is what is half-way through the night? I'd rather the PC shut off the load at a specific time (like 1 AM for example) so that way the lights shut off consistently every night.
Probably six hours. The FPOLC/Sun-Tech one is called the "Midnight Tracker" and I think it turns the load off at midnight. I had a Midnight Tracker that I used for our landscape lights, but I don't have it anymore.