# Portable Solar Lantern Schematic

This portable solar lantern circuit uses 6 volt/5 watt solar panels are now widely available. With the help of such a photo-voltaic panel we can construct an economical, simple but efficient and truly portable solar lantern unit. Next important component required is a high power (1watt) white LED module.

When solar panel is well exposed to sunlight, about 9 volt dc available from the panel can be used to recharge a 4.8 volt /600 mAh rated Ni-Cd batterypack. Here red LED (D2) functions as a charging process indicator with the help of resistor R1. Resistor R2 regulates the charging current flow to near 150mA.

Assuming a 4-5 hour sunlit day, the solar panel (150mA current set by the charge controller resistor R2) will pump about 600 – 750 mAh into the battery pack. When power switch S1 is turned on, dc supply from the Ni-Cd battery pack is extended to the white LED (D3). Resistor R3 determines the LED current. Capacitor C1 works as a buffer.

Note: After construction, slightly change the values of R1,R2 and R3 up/down by trial&error method, if necessary.

## Related Tutorials

• Harsh Mehta

Hello everyone. This page gave me a lot of information relating my project.
I’m designing a low cost Solar Home Lighting System which I’ll gift to my relatives residing in a remote area in Rajasthan, India where there is abundant solar power available.
I want to use 5Watt 6Volt Solar Panel, 6V 4.5Ah Lead Acid Battery,
2 x 1.5W (6V) DC LED Bulbs and 1 output for Mobile Charging.

I want to design a battery overcharging protection circuit for the 6V 4.5Ah battery and also a 5V/5.5V Output with constant current (around 500mA). Please help me with your suggestion and any circuit diagram if possible. I’ll be thankful for your replies.

• Anuj Verma

Sir,

I want to use 12 volts battery for “1W 3.6v 350mA” white LED which resistance should i use?

• ajinkya2906

Is this circuit is tested

• Antony John

Can I use a 6V SLA Battery with this Circuit

• Jim Keith

It should work, but may have limited life compared to nicads due to full discharge each day –that is the way these solar powered lights work.

• skushero

The Characteristics of a 1W LEd is 3.6v @350mA. . a 600mA battery will last less than 90 minutes if you need the depth of discharge to be approx 80%.

The panel 5W/6v Wp will have a max current of approx 500 to 800mA peaking at 800mA at noon . by restricting it to 150mA seems sheer waste . you can use a 1W panel to provide you 160mA at peak performance of 6 hours, to cover for the worst case scenario maybe 2W would be fine. thus reducing the cost of the panel.

The 1W LED will give approx 80 to 100 Lumens this can be provided by use of a series of 2 LED’s in a strings and have 10 strings each string @8mA for Ultra brightness so the consumption is reduced to 80mA. the battery would last for 6 hours providing illumination of approx 100 Lumens (each LED @4/5 Lumens and you can get 6 Lumens by adding a current limiting resistor in series with each string Too many components after the SPST warming the circuit wasting it in the 5W resistors

A simpler clever more efficient and better design is at electroschematics.com/6855/automatic-solar-garden-lights-with-leds/

• T.K.Hareendran

The design referred by Mr. Skushero is not efficient. I’d tested the circuit and found major flaws!

• Darktempt

hi there i think the R1=100ohms and the R3=22k ohms… how will you call it soLar if you use a battery??

sorry

• P. Marian

R3 is 3.9Ω and R2 is 22Ω both with 5W power dissipation.
“how will you call it solar if you use a battery?” – if it is a PORTABLE lantern will you use it in the daylight? You need the battery to store the Sun’s energy and then use the lantern in the dark, when there is no Sun.

• sp

what are the values for R1-R3 in ohms and the wattage

• gohil vishal

muje solar lantern kese banata uski sabhi internal circuit or diagram chahie me ghar ke liye banana chahata hu

• Jef

This is a very nice simple circuit. How long will it light the 1w LED? If I’m correct, a 1 watt LED at 3 volts uses about 333ma so if the batteries are 600mah then around 2 hours?

• Suraj kshirsagar

sir,
muje solar pannal kaha milega? aur uski prise kya hogi?
muje aapka ckt bahut asha lag.
thank’s

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