A wireless power system with an after closing hours mode

New systems for ensuring the reliable function of systems for laser powering and information propagation using receivers located in premises frequented by the public, such as a store or a public office, using information displays. The systems employ a wireless power transmitter which has a detector for determining whether the premises is operating in a situation characteristic of normal working hours, with people present who may interfere with its correct operation, or whether the situation is typical of closed premises, with low or zero occupancy, enabling the system to operate reliably in what may be termed an "after-hours" mode. Operations which must be performed reliably include charging the receivers, updating of the displays, maintenance of the devices, and software updates. The system can detect the presence of human activity directly, or by implication by the cessation of services such as lighting or air conditioning in the area.