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Solar panel/led

Can anyone tell me if it's possible to power leds directly from a
solar panel? I need the light there and then, and not later on via
batteries. Hope this makes sense. Thanks for any advice
 
B

Bob Myers

Jan 1, 1970
0
Can anyone tell me if it's possible to power leds directly from a
solar panel? I need the light there and then, and not later on via
batteries. Hope this makes sense. Thanks for any advice

Sure it is. Now if you don't find that answer, by itself, particularly
helpful, you may want to stop and think about what additional
information you might have wanted to include in your question...

Bob M.
 
Sure it is. Now if you don't find that answer, by itself, particularly
helpful, you may want to stop and think about what additional
information you might have wanted to include in your question...

Bob M.


Keeping it simple, I want a "shed light" that operates during the day.
They seem to consist of a 12v led spotlight and a 5 watt solar panel
but most I've seen for sale don't have detailed specs. These would be
fine except I don't want to store the power
 
R

Rich Grise

Jan 1, 1970
0
Can anyone tell me if it's possible to power leds directly from a
solar panel? I need the light there and then, and not later on via
batteries. Hope this makes sense. Thanks for any advice

Well, this question might seem somewhat off-the-wall, but, just to
satisfy my curiosity, why do you need lights when the sun is shining?

Thanks,
Rich
 
M

Michael Black

Jan 1, 1970
0
Keeping it simple, I want a "shed light" that operates during the day.
They seem to consist of a 12v led spotlight and a 5 watt solar panel
but most I've seen for sale don't have detailed specs. These would be
fine except I don't want to store the power
Aren't you really confusing things? I don't know what "shed lights" are,
but the reason those garden LED lights have rechargeable batteries is because
the sun is out in the day, but you don't need the light then. At night, you
want the light, but there is no sun to power the LEDs.

So you use the sun in the daytime to charge up the batteries, so the power
will be available when the sun isn't.

Michael
 
S

Stephen J. Rush

Jan 1, 1970
0
Keeping it simple, I want a "shed light" that operates during the day.
They seem to consist of a 12v led spotlight and a 5 watt solar panel
but most I've seen for sale don't have detailed specs. These would be
fine except I don't want to store the power

If you only need the light in the daytime, wouldn't a small skylight or
window give you a lot more light for no more money?
 
B

Bob Masta

Jan 1, 1970
0
Keeping it simple, I want a "shed light" that operates during the day.
They seem to consist of a 12v led spotlight and a 5 watt solar panel
but most I've seen for sale don't have detailed specs. These would be
fine except I don't want to store the power

Sounds like your shed is as dingy inside as mine!
Others have suggested a skylight, but that assumes
that one skylight will give enough light, where you
need it. The LED approach allows the possibility that
you can move it around to different areas as needed.

The advantage of having the battery is not just at night.
Since the sun comes and goes behind clouds, the LED
brightness would fluctuate without a battery reservoir.

LED brightness is controlled by the current through them,
while the voltage across the LED is nearly constant. Without
some sort of current limiter, a tiny increase in voltage could
cause a whopping big increase in current and blow the LED.

So normally the LED is driven through a resistor or a special
current supply... almost *never* straight from a voltage source,
unless it is something with an intrinsic current limit. Your
solar cells may or may not fall into that category. My guess
is that you can probably come up with such a system, but
you might have to test a bunch of cells and LEDs first.

So, it's probably simplest to use the resistor or current
limiter right from the start. Personally, it seems simpler
(and probably no more expensive when all is said and
done) to use the ready-made battery system. They've
probably optimized it and gotten the prices down via
mass production in offshore plants... you will have to
pay more for the parts, even if you work for free.

Just a thought...



Bob Masta

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Signal Generator
Science with your sound card!
 
J

jasen

Jan 1, 1970
0
Keeping it simple, I want a "shed light" that operates during the day.
They seem to consist of a 12v led spotlight and a 5 watt solar panel
but most I've seen for sale don't have detailed specs. These would be
fine except I don't want to store the power

air, glass, and mirrors conduct sunligt a whole lot better than silicon and
copper. for light during the day some sort of window, skylight, or
light-pipe will be much more efficient than a solar-powered LED.

I don't think you'll find a 5W panel on those cheepie garden lights:
more like 0.05W
 
air, glass, and mirrors conduct sunligt a whole lot better than silicon and
copper. for light during the day some sort of window, skylight, or
light-pipe will be much more efficient than a solar-powered LED.

I don't think you'll find a 5W panel on those cheepie garden lights:
more like 0.05W


Thanks to everyone for the info. Sorry for the delay in replying.
Bob has it about right. The ability to use the light in specific small
areas is what I'm after.
I agree the standard battery system would be cheaper but presumably it
can't be charging and discharging at the same time, so it would tend
to deliver light only later in the day.
 
B

Bob Masta

Jan 1, 1970
0
Thanks to everyone for the info. Sorry for the delay in replying.
Bob has it about right. The ability to use the light in specific small
areas is what I'm after.
I agree the standard battery system would be cheaper but presumably it
can't be charging and discharging at the same time, so it would tend
to deliver light only later in the day.

I haven't actually used one of these battery systems, but I'd expect
that there should be no problem with charge and discharge. In the
morning, the battery will still be charged up from the prior
afternoon. In principle you could have a *much* brighter light
running from the battery, since it can charge over many hours
at low current input from the solar panel, then put out a much
bigger current for the short time you need it.

Best regards,



Bob Masta

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Signal Generator
Science with your sound card!
 
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