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LED solar powered lantern lights schematic

LED Solar Lantern Lights

solar led lantern ideaCircuit of the LED solar lantern lights presented here is built around one 6V/1W Solar Panel (PhotoVoltaic Panel) and a 4V/800mAh Lead-Acid Battery. Here, commonly available 5mm White Straw Hat LEDs are used as the light source.

how does the solar lantern circuit works

DC 6V supply from the solar panel is fed to the rechargeable battery through diode D1 (1N4007) and resistor R1 (15R). Diode D1 functions as a reverse current protector and resistor R1 limits the battery charging current to a safe value. Transistor T1 (BC548) is here wired as an automatic switch to control the LED driver transistor T2 (SL100). T1 disables T2 when the circuit receives sufficient power output from the solar panel.

Solar Lantern Lights Circuit Schematic

LED solar powered lantern lights schematic
LED solar powered lantern lights schematic

Switch S1 is an ordinary power on/off switch. Finally, resistor R4 determines the operating current of the white LED (LED 1 – LED 20) assembly. No-load voltage of the solar panel is near 7.2Volt. When connected with the circuit, the PV panel gives around 170mA of current at 6VDC output in middling sunlight, which is more than enough for this circuit. When fully charged, no-load output voltage of the 4V lead-acid battery is near 4.6Volt. According to datasheet, Forward Voltage of the 5mm (actually 4.8mm) White Straw Hat LED (used here) is 3 to 3.2volt, and maximum Continuous Current is about 20mA (Peak Current 30mA).

LED Solar Powered Lantern Notes

  • The design of this solar powered lantern is flexible! So, you can modify it as per your requirement & taste. However if you wish to change the PV panel and/or the re-chargeable battery, keep an eye on resistor R1. This also applies to resistor R4 when you are playing with the number of white LEDs
  • In the LED solar lights prototype, medium-power transistor SL100B (fitted with a small heatsink) was used as T2. This part number is not very crucial. You can try near-similar transistors as well
  • This solar lantern can also be charged from any 6VDC power source, capable of delivering the demanded current output

13 Comments

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  • Colin Mitchell

    Carlos Pote I already explained to you that the cost of electricity for one year is less an $2.00

    • Carlos Pote

      Dear Mr. Colin Mitchell,
      Thank you very much for your prompt reply to my question!
      About you already explained something to me related to the electricity cost, I don’t remember when that happened because this is my first intervention in this site to asking something to someone.
      What I meant to ask, once I don’t have knowledge about electronics, is all about how to make the circuit and how to chose the right components, how to calculate as their values as well. Which it will provides to me, a form for making this my project’s idea.
      Probably I had explained badly what I meant to ask you or you don’t understood what I need probably. About your bad understanding I have huge doubts of that, once you are an expert person in electronics unlike me. I don’t want to offend you with this my last comment to you. Probably, and I repeat, I explained badly what I meant to ask to you.
      So, Dear Mr. Colin, if you don’t mind and if you have availability of course, I need your help to make this my project, please. And I quote it again: “What I want to do, is create a circuit with a LED bulb (5050 SMD 18 LED Bulb 12 V 5W max.) and I need this Bulb connected, steady light, at least 16 Hours per day, daily which provide to me the signage of my house.
      So, Dear Friend, what I think that would be necessary to do my project is: The required solar panel; The required Battery; and a controller to control all the system, too.”.
      If you could help me out with this issue I will be grateful for eternity.

      Thanks one more time for your availability and for all your time.

      Warmest Regards

      Carlos Pote

  • Carlos Pote

    Hi, Dear T.K.Hareendran.
    Sorry for bothering you but I was looking for a solution on the web for my idea and fortunately I have found your projects here in http://www.electroschematics.com.
    I’m a person without knowledge in electronics and I have a project to make in my mind.
    I would like to know if you, sir, could give me an advice to make it.
    I live at a high point near an aerodrome and I’m afraid because the airplanes make the landing nearly my house.
    What I want to do, is create a circuit with a LED bulb (5050 SMD 18 LED Bulb 12 V 5W max.) and I need this Bulb connected, steady light, at least 16 Hours per day, daily which provide to me the signage of my house.
    So, Dear Friend, what I think that would be necessary to do my project is: The required solar panel; The required Battery; and a controller to control all the system, too. I know there are systems fed by the national energy net for this purpose in the market but, they have an expensive cost plus the value of the energy consumption which makes to me after an year a heavy factura and would like to make one system autonomous to reduce all the costs. If you could help me out with this issue I will be grateful. Thanks, and sorry for my english.
    Best Regards
    Carlos

  • Colin Mitchell

    This project can be done with a single transistor.

  • charan

    I had put this circuit in multisim ,but it is not working. Please help me in this regard.

  • pankaj

    Want to be a distributer.

  • mo

    hi.whats role of bc548 & ls100????????

  • jenovauh

    Can T2 be replace with another model as I could not find SL100 in my counter or even at eBay. Thanks

  • akki

    plz help me for project on solar panel garden light using LDR and rechargeble bettry…

  • Jyoti

    I want to drive 3watt load having 25 parallel pair of 2 straw hat white led in series total consist of 50 leds..with a 6V 4.5ah SLA battery.kindly suggest me how to calculate the values of R1 and R4. and what would be the best suitable solar panel should i use to charge the battery. and how can we indicate the low battery level and an indicator to full battery charge..

    REPLY ASAP

    Thankyou..

    • T.K.Hareendran

      Note that Forward Voltage of a white straw hat LED is 3 to 3.2V & maximum Continuous Current is 20mA. Driving two such LEDs in series combination with a 6VDC supply is not a good practice (consider the voltage drop introduced by the driver transistor).Further, a 6V/4.5 Ah battery will not get sufficient charging voltage/current from a 6V solar panel!

      This calls for a new design work & I will try to publish such a circuit in near future. Thanks for your keen interest in my published design.

  • T.K.Hareendran

    In the text of the article, part number of LED driver transistor (T2) is shown as BD139. The correct number is SL100. I regret for the misprint.

    • Jyoti

      I want to drive 3watt load having 25 parallel pair of 2 straw hat white led in series total consist of 50 leds..with a 6V 4.5ah SLA battery.kindly suggest me how to calculate the values of R1 and R4. and what would be the best suitable solar panel should i use to charge the battery. and how can we indicate the low battery level and an indicator to full battery charge..

      REPLY ASAP

      Thankyou..

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