Welcome to the PLCTalk forum community !
What model of A-B logic controller are you using ? How are they networked ?
Are these small controllers that control one solar panel frame each, or a larger controller that controls many follower mechanisms ?
Do you have any sort of HMI (PC or hardware based) that gets an accurate time value from an Internet or other reliable time server ?
There are several ways to set PLC time clocks, including a software utility that runs on an HMI or server computer, or a high-precision ControlLogix module, or some roll-your-own clock data setting logic.