A low-voltage direct supply system capable of switching between solar energy and mains supply comprises: a solar and stable-voltage energy storage branch system used for providing solar power supply and charging through multiple groups of extensible solar panels and an energy storage battery pack; a mains power supply stable-switching branch system used for quickly switching to mains power supply without shocks through a mains supply conversion module and charging the energy storage battery pack; a power supply load detection and control branch system used for detecting a voltage, a charge/discharge current, and a balance between supply and demand of the energy storage battery pack and performing switching control on branch systems; and an output balance and low-voltage direct supply branch system used for performing balanced low-voltage direct supply on a load side according to a control output signal of the power supply load detection and control branch system.