All buildings have areas which are in darkness during day time. In such locations we can use a solar day lamp. The lamp will turn ON when the sun rises and will turn OFF when the sun sets. There are no switches to be turned on or off. It will convert the previously dark area into perpetually bright area through out the day.

The total cost of this lamp will be about 700 Indian rupees.

Step 1: Material required for making solar day lamp

Material required:
You need following material (see figures)
1. Aluminum Channel
2. Wooden batten
3. Wood screws 0.5” long
4. Plastic or fiber washers 3 mm inner diameter
5. 5 White LEDs 1W rating
6. 3 Way terminal strip and mounting screw/nut.
7. Solar PV panel 12V 5 W
8. Wires
<p>I just had a question, provided these are white leds, these have a forward voltage of 3 volt. So that adds up to 15 volt, which is more than the 12 volt delivers.</p><p>Also, if theyare 1watt, they draw 333mA current. Over the 15 ohm resistor that means 5 volt drop.</p><p>Add to that that the sun will not always be brihjt enough to have the pv deliver the full 12 volt.</p><p>So how does this work? am i missing something?</p>
<p>Dear diy_bloke</p><p>Your question is very valid. </p><p>A 12 V PV panel actually has a voltage rating of 17 V at maximum power. It has an open circuit voltage of about 20V. Why it is called as 12 V PV panel, my guess is, it is used for charging 12 V battery. </p><p>The 15 ohm resistor is designed as a worst case value. In summer the panel may generate much more than 5 W of power. That is because, 5 W rating is specified at standard condition of 1 kW solar power per 1 sq meter area. In summer the solar intensity goes well beyond that. Which means the PV panel may supply more than 19 V at full load. Taking this into account 15 ohm resistor is included. </p><p>Normally, the LED current is in the range of 150 to 250 mA range. This provides good light output. If more light is required kindly see the article &quot;High Power Solar Day Lamp&quot; in instructables. Usually, the life of LED depends upon the current flowing through it. So, if lower current is flowing through the LED it will have longer life.</p><p>Lastly, even during cloudy days with sufficient light, these PV panels do generate good open circuit voltage which is greater than 15 V. Hence the LEDs will always be forward biased and will be ON. The intensity of light from LEDs may be lower. Until the sunlight intensity goes very low such as in the evening, we keep getting light from the LEDs</p><p>I hope I have clarified to your satisfaction.</p><p>Thanks</p><p>-Abhijeet</p>
<p>clear, tnx</p>
<p>Dear diy_bloke</p><p>Please have a look at one more add-on feature for solar day lamp at following link:</p><p><a href="http://electronicdesign.com/power/solar-day-lamp-also-powers-fm-receiver" rel="nofollow">http://electronicdesign.com/power/solar-day-lamp-also-powers-fm-receiver</a></p><p>Thanks</p><p>-Abhijeet</p>
<p>thank you. i will</p>
Please also have a look at this new article &quot;High Power Solar Day Lamp&quot; at following link. <br> <br>http://www.instructables.com/id/High-Power-Solar-Day-Lamp/step10/null/ <br> <br>Thanks <br>Abhijeet
Thanks for Info .. Approx cost???
Dear Friend, <br> <br>where i can get solar panel in India - Ahmedabad ? <br>can you help me please... <br>
Pl indicate suppliers of Solar panels in Bangalore .
Hi, <br> <br>You can contact Surana Ventures. They might send you to Ahmedabad by courier. <br>thanks <br>-Abhijeet <br> <br>Marketing Executive <br>SURANA VENTURES LTD. <br>5th Floor, Surya Towers, <br>Sardar Patel Road, <br>Secunderabad-500003 (A.P.) India. <br>Contact No.+ 91-40- 27845119, 44665799 <br>harika@surana.com <br>web: www.suranaventures.com <br>
Pretty neat, 1 thing that i would recommend is to get a piece of plastic-wrap or film to put over the PV panel. Gives you rain protection and will keep dust from directly touching any circuit which could be fragile.
nice instructables :D very usefull <br>
To enhance the utility of this day lamp following additions could be made to the basic circuit. It consists of two LED arrays, one PV panel and one two-way switch. <br> <br>1. Make two units of LED array and install them at two locations where light is required. <br>2. Take a two-way switch. This has three terminals. Connect positive wire from PV panel to the middle terminal of two-way switch. <br>3. Connect the remaining two terminals of the two-way switch to the respective resistors of each of the LED array. <br>4. Connect the negative wire from the PV panel to the negative terminals of both LED arrays. <br>5. Now you can turn ON any one of the LED arrays by using the two-way switch. <br> <br>Thanks, <br>Author <br>(Abhijeet Deshpande)
nice one! i like it!
Awesome and very low cost. :D Great work!

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