Solar power is free energy and it comes from the sun.
It is clean and is renewable, because of this solar lights are very popular today.
This is Automatic Solar LED Light Circuit and it turns ON light at night, and it turns OFF light at day automatically.
In this circuit there is no switch is required.
This project is useful for garden lights, street lights and is useful for emergency lights also.
Circuit Working:

Parts List:
| Components | Specification | Quantity |
|---|---|---|
| Resistors | 22k , 1k 1/4 watt | 1 each |
| Semiconductors | Transistor 2N2222 NPN | 2 |
| White Super Bright LED | 1 | |
| 1N5819 Schottky Diode | 1 | |
| 3V to 6V, 200mA Solar Panel | 1 | |
| 1.2V AA Rechargeable Battery, 1500mAh | 1 | |
| Inductor 20 turns each, 36 AWG wire, 10mm Diameter Ferrite Toroid Core | 1 |
First, let us see daytime working of the circuit.
During day the solar panel produces voltage and this voltage charges the battery.
At the same time the solar voltage reaches transistor Q1 and Q1 turns ON.
Then Q2 remains OFF and because of this the LED stays OFF.
So during day the charging happens, but light does not turns ON.
Now let us see night time working.
At night the solar panel voltage becomes zero, so Q1 turns OFF.
Because of this the Q2 gets base current and Q2 starts switching.
Inductor boosts voltage.
Then LED turns ON automatically and thus light glows at night.
Therefore, day night operation happens automatically.
How to Build:
To build a Automatic Solar LED Light Circuit follow the below connection steps:
- Take all the parts as shown in circuit diagram.
- Transistor Q1 emitter pin is connect to ground.
- Base connects to one end of R1.
- Collector connect to R2 and base of Q2.
- Transistor Q2 emitter pin connects to ground.
- Base connect to R2 and Q1 collector.
- Collector connect to L2 inductor and LED anode.
- Diode 1N5819 anode connect to solar panel positive and resistor R1.
- Cathode connect to inductor and battery positive
- Battery negative goes to Gnd of the circuit.
Conclusion:
This Automatic Solar LED Light Circuit is simple and useful project.
It uses very few components and it works reliably.
Most importantly it saves energy and it works without human effort.
It is best for beginners and therefore, this circuit is highly recommended.
It is useful for daily life and it is also good for learning electronics.
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