Is it possible to have SS take a single photo at the same time each day?

Yes - the easiest way to accomplish this is using an AppleScript that you schedule to run every day.

A simple script to capture an image would be as follows:

    tell application "SecuritySpy"
        capture image camera number 0
    end tell

SecuritySpy will capture an image from the camera to its default location (i.e. ~/SecuritySpy/Captured Files, or whatever capture destination path you have set for the camera). You also have the option to add a custom path to the AppleScript command like this:

        capture image camera number 0 as "/Users/mlevin77/Desktop/image.jpg"

You can schedule your script to run every day at a specific time by following our instructions here: SecuritySpy - Scheduling AppleScripts.

The easiest way to do this is to add the "epoch time" to the file name (it's the number of seconds since midnight 1 January 1970, but the important thing is that it increments every second, so it's useful for producing unique file names that conserve the order of creation). Something like this would work:

    set ET to do shell script "date +%s"

    tell application "SecuritySpy"
        capture image camera number 0 as "/Users/mlevin77/Desktop/image-" & ET & ".jpg"
     end tell

For info about discovering your camera numbers, see the "Camera Numbers" section near the top of the SecuritySpy AppleScript Examples page.

Did you also add the first line? set ET to do shell script "date +%s"