Direct-current common grid control device applied to photovoltaic power generation

The invention provides a control device for enabling photovoltaic electric power and commercial power direct current to be applied in a common grid, which comprises a current converging unit, a commercial power access unit and a control unit, wherein a microprocessor chip of the control unit adopts a C8051f020 chip. The control device has the advantages that: direct-current electric power generated by a photovoltaic system is connected with transformed and rectified commercial power of the same voltage class as that of the photovoltaic system to supply power to a direct-current electro-load common grid; and the photovoltaic electric power is used preferentially without storage batteries and the commercial power is used as stand-by power, so that the photovoltaic electric power is 'used immediately after being generated' and the photovoltaic electric power is furthest utilized and has the function of control protection.