Morningstar Sun Light 20-24v Charge Controller Morningstar�s advanced SunLight solar lighting controller combines the SunSaver design with a microcontroller for automatic lighting control functions. This Technology Provides: Proven Reliability Precise Lighting Control PWM Battery Charging Operation: Rotary digital switch to select among 10 lighting options (see back) Test button flashes red LED to confirm correct rotary switch selection Test button turns lights on for 5 minutes (in LVD limited to 3 times) LVD overrides lighting timer Sunrise overrides lighting timer Timer accuracy is within 2 seconds