I got the idea from the Sutherlands. They explain how they use their Helix and the photo cell to control the night time drops for their ball racks.
So here is how it works. You place the probe of the Helix into the rack or cage you want to control. Set the daytime temp you want and then plug in the photocell. Once the photocell is plugged in you can set the nighttime temp you want.
Once the sun goes down the photocell registers that and automatically tell the Helix to change the cage temp to the desired nighttime temp. In the morning when the sun comes up the basking spots automatically get bumped back up to the desired daytime temp. With this device your snake always have a hot spot for the same amount of time they have sunlight. So as the days shorten in fall and winter so does the amount of basking time they have. This helps make their cage a little more natural. With the photo cell there is no more having to be there at sun down or sun up to turn the heat pads on or off. Or if you are using a timer there is no more having to readjust it every week or so as the amount of sun light changes. It just makes life a little easier by automating the cycling of your snake racks. I have two helixes and two photo cells now and will probably get more.
Next year when I move my snake room to a bigger room I will be getting a Helix to control the heater for my room which I will also be hooking up to a photo cell so that my ambient room temp will also be in sync with the amount of sun light there is. In the wild when the goes down the temps go down so why should it be any different in captivity?
Cheers,
Trevor