You can use the 2 volt plugs with a power panel but may have a problem in lighting them up with a single Nixx cell. A power panel always puts the full 12 volts across the plug for a short time (typically 10 milliseconds every 100 milliseconds) so that it averages out to what a 1.2 volt cell would deliver. By adjusting the pot (it determines the ratio of on/off time the 12 volts is supplied) you can change this effective power a bit when using a power panel.