Power solar panel by flashlight

So, i just bought 10w solar panel
Just for…researching :stuck_out_tongue:
It is rated 17v 0.55A
Since it’s night now so i just power it by my olight x7, go on turbo(9000 lumen), the voltage output is quite legit(18.8V), but the current is very low( about 0.1-0.2A), so the solar panel can’t do anything now
I will test it tomorow, at day, under sun, but do any of you think what’s wrong with my test
Pretty sure 9000 lumen can do something

One of my theory is the lacking of UV light, but, who knows?

Have several lights around the house with little solar panels
When I am up early and it was raining the day before it is funny to shine on one with a flashlight and see it work for a little while, but it is very inefficient but will try with a UV light next time (well now with longer days they all work in the morning so this might take a while. :wink: )

so, with the same brightness to my nake eye, will the output power be different between sunlight and flashlight?

“Multiplying the figure of 1050 watts per square metre by 93 lumens per watt indicates that bright sunlight provides an illuminance of approximately 98 000 lux (lumens per square meter) on a perpendicular surface at sea level.”

That’s quite a bit more than your 9k lumen light…
What are the dimensions of your solar panel?
Not sure if there is any difference from the broadband light source of the sun vs. the very narrowband light source of an led flashlight.

Try a 10k lumen incandescent spotlight and see if that works better… :smiling_imp:
(solar panel with hole burned through…)

If the flashlight is close to the panel you can easily get 100000lux which is the rough equivalent of sunlight, but the spectrum does make a difference. In Si solar panels all photons with wavelength less than about 1100nm (corresponding to the ~1.1ev band gap of Si) is absorbed and, ideally, leads to one electron per photon in the current. The LED spectrum lacks the IR region, UV region, and some parts in the visible. So you won’t get as much current from a flashlight as from the sun if the illumination intensity (lux) is the same.

okay, i will test it tomorow, under sunlight

I’m confused.

I love solar panels and often use them to charge my cells.

but let me get this straight.

(a) You want to make a solar powered flashlight?

Well I guess you can get it to work, but best during the middle of the day and in the light (d you see see any problems with this) :wink:

If your not trying (a) above then just use the solar power to charge the cells (when they are not needed, aka the middle of the day) and use flashlight in the dark (much more effective this way :wink: ) and then it is a beautiful marriage. :slight_smile:

’oogled that for you

And if you want to make your own spectra, here’s the kit tool:


For example: SpectralWorkbench

SpectralWorkbench is the BLF Special AAA flashlight

Thank you very much, you guys are such infomative
I just tested it under sunlight, yeah, it has much more power, the output is 21V, and the current when short circuit is about 0.4-0.5A
Now i know what will i do next

No, it was just experiment, too see how strong is sunlight compare to flashlight, and the effect of unseenable wavelength to SolarPanel

One thing i don’t understand
I once visted a solar panel factory, and i saw them test the panel in room, by a xenon light( i guess), not under sunlight, i don’t know how can they sure about their quality if they don’t check under sunlight

Xenon puts out a spectrum closer to sunlight than the other types of light.
First they test with sunlight, then test with xenon, observe the % difference in power,
and use that known information going forward so all future tests can be done with xenon, adjusting for % difference to sunlight.

Step 1. Power solar panel using flashlight
Step 2. Use solar panel to charge flashlight
Step 3. ?
Step 4. Free energy?

Step 3. (chainsaws!, explosions!, danger!)