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Just recently got interested in starting up a new project out of my area of knowledge.

Basically I'm going to buy a 3v 200ma solar panel that I want to use to power a small light in one of the rooms in my basement.

I plan on buying this one:

http://www.amazon.com/gp/product/B00IWZWT6S/ref=oh_aui_detailpage_o00_s01?ie=UTF8&psc=1#Ask

My question is, what else do I need besides the solar panel to get going on this? What exactly do I need in between this solar panel and the light bulb? Any resources would be great to help me start up on this new project. Thanks in advance for the help!

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  • \$\begingroup\$ Do you need the light to come on when the sun is not available? I mean, do you need a battery? Also, what kind of light is it? What power source does it require? \$\endgroup\$ – mkeith Apr 15 '15 at 4:37
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If you are thinking about using just one of those panels and a standard incandescent house bulb - forget about it ! -. That panel only produces 0.6 watts of power, and that's likely only in fullest sunlight.

You may be able use a very small DC bulb from a flash light (torch) with that panel. If using a small 3V 200ma incandescent bulb you could connect it directly to the leads of the solar panel. Of course with no other components (like a battery), when a cloud goes by the light goes bye-bye.

Another option would be to hook up 10 red or yellow LEDs in parallel (with a 51 ohm resistor in series with each LED). That allows about 20ma per LED. This could also be connected directly to the panel output (observing polarity of the LEDs).

The 3V output would not quite be enough to directly drive most white LEDs as they tend to need 3v or more. There are booster circuits available that could increase the voltage to drive a white LED, but with only one solar panel you would still be limited to 0.6w (or less depending on the efficiency of the booster). - Here is one example of a voltage booster that might be used - http://www.icstation.com/icstation-mt3608-step-booster-power-apply-module-p-3448.html

To get any significant light output you would need to buy several panels and place them in series or parallel to get higher power levels.

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The sibling comment about using ten yellow LEDs with a 2V forward voltage is the best idea, although in this very specific case you don't even need the series resistors, as the panel will not be able to output 3V at 200ma. (I suspect I'm going to get comments arguing with this, but it's true).

To visualise the amount of light you can get out of this system, imagine adding a window to your basement that's about 5% of the size of the panel. For any size of panel.

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