White of the photo cell, incoming white and white to light all connected together. Black of photo cell to incoming black. Red of photo cell to black going to light.

If the cell has only two connections, it will not matter, since a photo cell collects light and emits an electrical signal depending on the amount of light it receives. I used to put them in polaroid cameras, and they could go in either way. There was no plus side and negative side if that's what your asking.

The typical photocell used in building wiring does need to be wire correctly, it will have three wires, the Black must be the live feed, the red is the switched conductor, and the white is the neutral.

The circuit inside needs constant power from the black and white input for the control to operate properly. The red will be live only when the control does not see daylight, the control will close the internal switch, and energize the light fixture it controls.

If the control is wired backwards with the black and red, it will not operate properly, it will turn the light fixture it controls on and off all day and night.

Here is some detail from a popular manufacturer:

Precision Multiple Controls, Inc. for photocontrols, photocells, timers, switches, lighting controls, and pool timers. (http://www.precisionmulticontrols.com/Wiring-diagrams.html)

White of the photo cell, incoming white and white to light all connected together. Black of photo cell to incoming black. Red of photo cell to black going to light.
HK, this answer is OK in a perfect world and if the wiring is all the same as you describe.

This is the only correct answer:

The typical photocell used in building wiring does need to be wire correctly, it will have three wires, the Black must be the live feed, the red is the switched conductor, and the white is the neutral.

If someone does not know what a neutral is, or how to verify a feed and switch leg they need to hire someone who does.

If the cell has only two connections, it will not matter, since a photo cell collects light and emits an electrical signal depending on the amount of light it receives. I used to put them in polaroid cameras, and they could go in either way. There was no plus side and negative side if that's what your asking.Sorry, this is completely wrong in the world of AC building wiring.