A street-lighting and solar energy collection system is disclosed. The system comprises a plurality of lighting/solar energy collecting units, an AC and DC power transmission means and a control unit. The system operates in one of the two operation modes. In the first operation mode as the street-lighting system, the units receive AC power from the power grid for lighting. In the second operation mode as the solar energy collecting system, the units transmit generated DC electricity to a centralized DC to AC converter in the control unit. The control unit further provides a means for switching the system in between two modes. When the system is operated as the solar energy collection system, it is disconnected from the power grid. The generated DC electricity from each unit is converted by the AC to DC converter in the control unit and is subsequently injected into the power grid. Communication devices in the units and in the control unit form an ad hoc communication network. Instructions for operations can be sent from the control unit to the units. Further, the operation status from each unit can be collected and be sent to the control unit.