Because photocells are basically resistors, they are non-polarized. That means you can connect them up 'either way' and they'll work just fine!
Photocells are pretty hardy, you can easily solder to them, clip the leads, plug them into breadboards, use alligator clips, etc. The only care you should take is to avoid bending the leads right at the epoxied sensor, as they could break off if flexed too often.This guide was first published on Jul 29, 2012. It was last updated on Sep 24, 2018. This page (Connecting a Photocell) was last updated on Dec 08, 2017.