Group 78 is a 34/78 A general motors specialty.
Unless the voltage regulator in the alternator has been bypassed or subverted there is no way on earth a 1117437 or 1116413 Delco regulator can be over-riden and the stator sense lead regulator bridge between the rectifier and regulator will shut down the voltage regulator. The PLIS / PLFS regulator plug circuit can be manipulated to increase voltage to the point of sense default which reverts the voltage regulator to an internal voltage sense condition. This usually generates a dash warning lamp and stored fault code. 14.4 is normal.
Like all Delco regs the CS series contains a thermistor in the "S" circuit that moderates voltage but the sense is limited to interior alternator temperature.
Solar panels or charging augmentation can certainly increase circuit voltage but it is certainly not a function of any Delco or Delphi voltage regulator.
