i once built a "dark sensitive" night indicator for light switch using a red LED
those things have a half life -- mine lived 1.5y it was like continuosly on no PPM/PWM dimming/opt.-ing
tough it was years ago (LED-s were not so developed) and i pushed it near it's max rating - for 1-st y all nice and cool

 

Now, they will come on earlier on a cloudy day. If you don't want that and really want to synch with the sun, then I suppose the hardware store options aren't up to it.

And that to me is the real question. If the TS is quantifying a certain dim ambient light level as "an hour before sunset", then what he needs is an optical sensor circuit or device adjusted to that light level. If he really wants it to trigger 1 hour before the astronomical sunset no matter now light or dark it is at that time, then he needs something with more brains. A combo solution uses the sunset calculator to enable the optical sensor, so there are no false triggers at 12 noon on a dark and stormy day. Life is choice.

ak

 

How can this be such a difficult problem? There are so many obvious solutions:

1. Detect sunset and time travel 1-hour back to turn on the deck lights.
2. Detect sunset and set timer to turn on 23 hours later.
3. Locate your solar sensor in a time zone one hour ahead and relay the data via internet. (Edit: Oops. I see this wouldn't work. You are located on the North American Eastern seaboard.)
4. Program in your sunset data into a microcontroller.
5. Use a standard mechanical timer set to turn on at 1700h. Adjust manually as required.

Here is your sunset data (change location as desired):

https://www.timeanddate.com/sun/usa/jersey-city

 

And there's also the Astronomic timer I suggested in post #5.

 

it should think the modern boats ought to have some sort of navigational - the gig'd be to tweak the coordinates out from - tough cellphones were able to "voice dial" before y2k (i know everyone is getting more and more brain dead nowadays) but i think you can get some sort of voice recognition gizmo to your smartphone and bluethooth or ir or tone encode ring the data to your lights control

 

Arduino solutions

• Store sunset times on removeable media (simpler coding)
• Based on a RTC (Real Time Clock) calculate the sunset (simpler hardware; more coding)
• Project the next sunset based on the actual sunset today (simpler hardware; simple coding; not as accurate without RTC)

An Arduino SD Card shield, RTC and a relay module in addition to the Arduino board is proposed.

The SD card holds a table of the universal times for the pre-sunset turn-on times. The Arduino periodically checks the next time from the table and turns on the relay module.

Without the stored table, one can use the calculations based on the web, to project the sunset time. Constants such as latitude, longitude and declination can be stored in the sketch.

One can simply count, using the internal clock, for 23 or so hours. A light sensor can detect sunset with projected times as a filter for dark and rainy days. This is the least accurate method.

 

Along the line with crutschow's suggestion in post #5, Leviton Vizia+ timer in Decora style wall switch uses 24-hour clock and geographical location for sunrise/sunset programming.