Can you get solar power from an LED?

ScubaSnyder · Nov 7, 2008

I have only taken Physics I and II and I am wondering if it is possible to make a light that can self charge off of its own emitted light? I know that light could not generate enough solar energy(if any) to self charge lion cells to a point where the light could run on low ? This may be a dumb idea but with all of the new technology with capacitors and solar could we make a light that is self-sufficient with a low light power?

Its late and just and Idea so please dont flame me, but as an avid backpacker/field scientist I fell something can be created.

t3h · Nov 7, 2008

Conservation of energy. If you have 10W of light coming out the front, and then capture it with a 100% efficient solar panel (impossible), you'll have 10W of power. The problem is, though, that you'll be able to use 0W of that light, as it's all going to recharge the battery. Hence this will not work.

This, however, is another concept: using an inductive charge pump to draw nearly all the energy out of a battery: http://www.bigclive.com/joule.htm

It's possible to do this with a rechargable, but I wouldn't as it will ruin it. But running a single LED off 1 flat AA is quite cool.

worldedit · Nov 7, 2008

Cant work, theres allways a loss when you transform power (from electricity to light and back).

Juggernaut · Nov 7, 2008

Even if such a theory could work you would have to understand 100% of the light would have to hit the solar panel, thus there would be no light for you to actually use:thumbsdow. Example: the light would have to be placed directly on the panel with no gaps, it like having unlimited energy in a wire but it would have to go around and around in a loop, you could never open it up to use some or it would run out. So even if the laws of Conservation of energy were false, you could never use any of the power. "Like having an alkaline battery that would never leak and loss power:twothumbs when sitting on a shelf, but when you inserted it into a light it would just run out.:thumbsdow"

NeSSuS-GTE · Nov 7, 2008

If you have taken Physics I and II then you already know nature's most fundamental law of physics.

If you don't remember the Second Law of Thermodynamics then read this wiki. You will then understand why your suggestion won't work.

http://en.wikipedia.org/wiki/Second_law_of_thermodynamics

brucec · Nov 7, 2008

Not to mention a bandgap of 3.5eV is fairly large. Then on the other hand, there are reports of some people's flashlights not turning on in direct sunlight, presumably due to some kind of reverse voltage.

Marduke · Nov 7, 2008

I think the best you could hope for is a VERY small tickle charge when the emitter is in direct sunlight and the light is not in use. However, the increased self discharge of your cells at the increased temp of being in direct sunlight would far outweigh the any minuscule trickle charge effect.

kramer5150 · Nov 7, 2008

not possible, due to efficiency losses.... you're fighting the conservation of energy in the natural world.

Juggernaut · Nov 7, 2008

NeSSuS-GTE said:
If you have taken Physics I and II then you already know nature's most fundamental law of physics.

If you don't remember the Second Law of Thermodynamics then read this wiki. You will then understand why your suggestion won't work.

http://en.wikipedia.org/wiki/Second_law_of_thermodynamics

I haven't and I know:nana: :sssh:

.

ScubaSnyder · Nov 7, 2008

Thanks for the replies, After I read my post I forgot a lot of details, I was not looking to fully charge the battery but a small slow trickle to increase runtime I was thinking of a way to incorporate solar panels/material at the end of the reflector(cut the reflector short ring of solar material), I should have made a drawing I guess.Id imagine a light like this could be made to use the reflector to catch sunlight to charge the battery with light from the sun when its off but would almost be better to have the panel on the body as I have seen before.

HKJ · Nov 7, 2008

ScubaSnyder said:
Thanks for the replies, After I read my post I forgot a lot of details, I was not looking to fully charge the battery but a small slow trickle to increase runtime I was thinking of a way to incorporate solar panels/material at the end of the reflector(cut the reflector short ring of solar material), I should have made a drawing I guess.Id imagine a light like this could be made to use the reflector to catch sunlight to charge the battery with light from the sun when its off but would almost be better to have the panel on the body as I have seen before.

Remember that any light your capture with solar cells are not used to light up the outside and because the solar cells has a efficiency below 100%, your are wasting energy.

You can buy flashlights with solar cells on the body.

Can you get solar power from an LED?

ScubaSnyder

Enlightened

t3h

Newly Enlightened

worldedit

Enlightened

Juggernaut

Flashlight Enthusiast

NeSSuS-GTE

Newly Enlightened

brucec

Enlightened

Marduke

Flashaholic

kramer5150

Flashaholic

Juggernaut

Flashlight Enthusiast

ScubaSnyder

Enlightened

HKJ

Flashaholic

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