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PIR Solar Home Lighting Circuit

Last Updated on by 23 Comments

The post explains a simple circuit using Passive Infrared or PIR for making an automatic solar LED lamp which can be used for illuminating your home automatically at sunset, and only in the presence of a human member in the premise.

By SS Kopparthy

Introduction

Here, in this article, a simple yet useful and improved version of the PIR based automatic home lighting system is discussed. A previous version of this circuit is already discussed and is available here: https://www.homemade-circuits.com/pir-motion-activated-relay-circuit/ The major improvement is the static detection of human beings and also it works completely on solar energy unless the battery doesn’t get charged on a rainy day or something.

Circuit Working:

The circuit consists of different stages, where each one performs a specific task to keep the circuit working. The first one is the solar panel, solar charge controller and the battery which together control solar based power supply to the circuit. The same stage decides whether power is to be fed from the battery or from the mains, depending on the battery charge and voltage.

Circuit Diagram

PIR controlled LED solar lamp circuit

A 8550 PNP transistor is used here in the solar charge controller to decide it is day or night depending on the voltage form the solar panel. This is achieved by feeding the solar panel voltage to the base of the transistor hence holding it off during the day time when the voltage is produces by panel. When the dusk sets in the voltage drops across the transistor and battery voltage gets routed to rest of the circuit.

The next stage is a voltage source switcher that decides whether the circuit should be powered using battery voltage or the AC power source depending on the battery voltage level. A DPDT relay is configured to take care of this switching. Hence, the power to the circuit remains uninterrupted.

The next stage consists of the day/night detector that senses whether it is day or night depending on the sunlight incident on the LDR and it triggers the relay correspondingly. A capacitor C1 is attached at base of the transistor T3 in this stage. That makes sure that a small delay is introduced in the sensing so that sudden changes in the intensity of light does not false trigger the circuit. Output of T3 is fed to the next transistor Q1 which actually triggers the relay.

Final stage consists of a PIR sensor HC-SR501 that produces a high output when it detects the presence of a human being in its vicinity which is fed to the base of the transistor Q2 and immediately it fires the relay and the LED’s connected to it gets lit up. When the human moves away, the light gets turned off automatically using the same mechanism.

Finally, for the circuit to work even when there is static occupancy, the an additional stage consisting of the Hex Schmitt trigger IC and few other components may be used in combination with the existing circuit, but please remember to use a bigger battery and solar panel as per requirement. The circuit can be found here: https://www.homemade-circuits.com/pir-circuit-for-detecting-static-or/

List of Components:

Solar panel- 10.2V,400mA, 6Watts,
BATT1- 6V, 4.5Ah battery
R1- 1K
D1, D2, D3, D5, D6- 1N4007
D4, D7- 1N4148
R2- 10K trimpot
R3- 200E
R4- LDR
R5, R8, R9- 1K
R6- 10K preset
R7- 10K
T1- 8050
T2, T3, Q1, Q2- BC547
C1- 10
RY1- 5V, DPDT relay
RY2, RY3- 5V, SPDT relay
L1, L2, L3- LED's
PIR- HC-SR501

Notes:

After completion of this automatic PIR based solar home lighting circuit assembly, the unit can be housed inside a suitable casing(plastic) and installed the in a safe position protected from weather. The solar panel, LDR needs to be located such that sunlight is incident on them directly.

Here is the video of my prototype showing the static occupancy detection, please note that solar panel is not connected to the circuit in the video as the circuit is indoor and also the circuit for PIR sensor motion is powered externally for the time being.

A Simplified Design can been seen below:

simple PIR based solar lamp circuit
get free help for circuit diagrams

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  2. As I am having a solar panel 3W 6V solar want to make a circuit board diagram dc to dc can u please explain which of the products are there as I am using 3.7v battery 18650.As it is to used for a passage

    Reply

  3. Hello Mr. Swagatam I hope you are well, I am very pleased with you. The information sharing you have shared is very valuable to me, so I pray for you every day. I used to be an electronic device repairman, now I quit because I am 62 years old, some of my opportunities are limited and I am struggling for life due to my orthopedic disability. I have a request from you. I need a voltage detector diagram that determines the place where the electrical installation and water installation goes under 40 cm concrete. I would appreciate if you could help me. Thank you very much for your precious time.

    Reply

    • Hi Neiio, yes it can be a 1N4148 or 1n4007 diode, although this diode and the 470uF are not required, since the PIR already has an in-built delay circuitry

      Reply

  5. hello sir, I want to built a solar light with this requirement :
    1. using 20 watt led light
    2. auto on at dawn and off in the morning.
    3.light on for at least for 12 hours.
    4.lithium battery fully charge in 5/6 hours
    5. built with battery overcharge and discharge protection.
    tq for your time..

    Reply

  6. Hi Swag,
    I want a circuit for a fan on/off switch (inductive load) for inverter, as the inductive loads have surge currents. My idea is to have a delay on switch which connect the fan (or any other inductive load) to the inverter after a delay of about 5/6 seconds. So that initial high current is bared by mains supply and after 5/6 seconds it is connected to inverter, spacifically solar inverter.
    Please guide in this matter.
    Anil

    Reply

  7. Hello and congratulations for your great work.
    I am looking for a booster circuit to replace a thief joule
    with a 5v solar panel, 4xli-ion 3.7v batteries, and also advice.

    thank you !!

    Reply

    • Thank you dijirotech,

      Joule thief is also a booster circuit? Please specify your exact technical specifications and also the solar panel amp rating, I will try to help!

      Reply

  8. Thank you for your reply.
    Could you please add the functionality so the light remains dim until movement is detected, and gets bright when motion sensors is triggered.

    Reply

    • You can try adding a 100K resistor or some other calculated high value resistor between TIP122 base and the positive line. It may do the job

      Reply

  9. Hello
    Can I use 7ah battery and 30W solar panel with this circuit?
    7805 IC dissipate too much current, can I use a switching regulator instead?
    Thank you for your good work.

    Reply