The QH-HL Infrared panel with LED lighting cannot be controlled with an existing light switch. The panel requires a constant power supply, which means the light switch must be left on at all times. If the switch is turned off, the power supply is interrupted and the panel no longer works. Instead, you can control the panel with the included wireless thermostat or remote control. You can control both the lighting and heating separately, so you can switch them on and off independently. A useful tip is to place the wireless thermostat next to the existing switch, so that you can easily switch between lighting and heating.