A photocell is used to trigger the circuit to open your door at dawn and close it at dusk. Therefore no programming is needed. Because the sunset and sunrise times change a little each day if you use a timer you will need to reprogram it several times a year. Photocells are used it street lights so they come on at night.
There is a knob in the Ladies First Chicken Door opener that allows you to adjust the sensitivity of the photocell. It will allow you to either close the door earlier and open later or close the door later and open earlier. Basically it will open and close at about the same light level.
A full moon, lightning or a passing light will not make the door open. If you shine a flashlight on it then it will start to open and as soon as you remove the light it will close. However any lights that shine on the coop directly where the photocell is will cause it to open. Like floodlights or security lights. If that is the case we could ship you a longer cable to move the photocell to another part of your coop for an economical price. Likewise a cloudy day will not cause the door to close.
The way the door opener is designed you simply drill a 1/4 inch hole through the back of the box and trough the front of your coop. You push the photocell through so it is flush with the outside of your coop. Or if you would rather we can supply a much longer cable with the light sensor to allow you to put it in a different location.