A standard Power Supply is usually fitted with a Transformer to step down the voltage from the mains and provide galvanic Isolation between the high voltage and low voltage section. In this Power Supply transformer is not been used for step down the voltage. Thus it saves a lot of space of weight of the Power Supply Unit.
Here is a solar charger circuit that is used to charge Lead Acid or Ni-Cd batteries using the solar energy power. The circuit harvests solar energy to charge a 6 volt 4.5 Ah rechargeable battery for various applications. The charger has Voltage and Current regulation and Over voltage cut off facilities. The circuit uses a 12 volt solar panel and a variable voltage regulator IC LM 317. The solar panel consists of solar cells each rated at 1.2 volts.