The present invention concerns a process for fabricating a solar cell, wherein material is deposited on a multicrystalline silicon substrate and passivation is performed by means of hydrogen plasma. The WT-DC includes an input signal optical monitor, a differential detector control circuit, a temperature controller, and an input signal dispersion compensator. The methods that can be invoked include get methods, set methods, unset methods, finder methods, destructors, and business methods. At the same time, processor activates a light emitter to provide a visual indication to the visitor that passage is permitted, and, simultaneously also activates the access allowed audio tone to be played through a message conveying apparatus.