The document describes a project report for a solar powered LED street light with automatic intensity control. It includes a functional block diagram and explanations of the components, including a solar panel, charge controller circuit, rechargeable battery, voltage divider circuit, and Arduino UNO microcontroller.
A solar panel is used to charge a battery via a simple LM338 based voltage regulator. The resistor values selected for the LM338 circuit ensures that the voltage to the battery never exceeds 14.1V thus make sure that the battery can never over charge. During day time the solar panel charges the battery to an optimal level.
Simple solar charger circuits are small devices which allow you to charge a battery quickly and cheaply, through solar panels. A simple solar charger circuit must have 3 basic features built-in: It should be low cost. Layman friendly, and easy to build. Must be efficient enough to satisfy the fundamental battery charging needs.
This must be precisely set such that the emitter produces not more than 1.8V with a DC input of above 3V. The DC input source is a solar panel which may be capable of producing an excess of 3V during optimal sunlight, and allow the charger to charge the battery with a maximum of 1.8V output.
The solar panel voltage specs may be anywhere between 18V and 24V. A relay is introduced in the circuit and is wired with the LED module such that it's switched ON only during the night or when it's dark below threshold for the solar panel to generate the required any power.
Referring to the 40 watt street light circuit diagram above, the panel voltage is regulated and stabilized to the required 14.4 volts by the IC LM 338. P3 is used for setting the output voltage to exactly 14.3 volts or somewhere near to it.