Instructables

Why does natural light work better with solar panels than florescent light?

I've found that when using solar panels to charge batteries and do other solar panel related projects, they work much better with natural sunlight over florescent lights. While I am willing to accept this fact and deal with it, I can't help but wonder why. Any ideas?

because sunlight is brighter and has not only visible light but allso UV and Infra Red light, wich fluorescent light bulbs don't have. and with fluorescent light bulbs you will get less energy than you're spending.
actually, fluorescent lights do produce UV light but the manafacturers put a white phosphourous powder on the tube to convert UV to white visible by human light.
3 reasons 1 amount of energy radiated 2 wavelength of light 3 number of photons per wave at night you can measure a solar cell's output when held next to a flourecent or flame then measure the same next to a incandescent light or moon exposure then measure it when exposed to a bright morning sky pointed away from the sun then aimed directly at the sun. allot of good data comes from this also a good spec sheet on the cell itself will explain and help inturpret the data.
jacob29105 years ago
because there are more photons in natraul light than in man made light
CRN5 years ago
First off the bread and butter of solar panels (photo voltaic cells) is that they use only the sun to create usable energy. When energy is converted from one form to another there is a loss. There for powering a photo voltaic cell with a florescent light is about as inefficient as you can get. Considering the loss that it took to power the home/office in the first place. The whole point of photo voltaic cells is to NOT use that man made energy and harness the infinite energy of the sun. But why? When a photo voltaic cell is in use its taking the flow of photons (light) and converting that energy to a direct flow of electrons (electricity as we know it). Currently photo voltaic cells are NOT 100% efficient at this task, currently you'll see about 5-15% efficiency. The cells do not respond to the light we see with our human eyes. Infrared light is what a cell responds to. Infrared light is the same light that comes out of your TVs remote control, don't believe me? Look at your remote through a digital camera and press buttons, you'll see it. This is the same theory behind night vision security cameras. I can't say how much Infrared light is being generated by the florescent bulb but it's not near what the sun is generating. Short Answer: -Sun is WAY brighter than any typical bulb. -Solar Panels use Infrared Light
Kiteman CRN5 years ago
(Sorry, but solar cells do not use infra red light - see kelseymh's answer for more.)
CRN Kiteman5 years ago
Well either way I was trying to say that solar panels see different light than we do. I thought it was infrared because I deal with it a lot. I'm an Audio/Video Technician and come across it a lot in video surveillance.
hg341 CRN5 years ago
well you are right but sp's try to use all of the light spectrum that they canat least the good ones
phalanx447 (author)  CRN5 years ago
Did you see the, well, I guess it could be called a "funnel" in Popular Science a few months ago that will increase the amount of light caught by solar cells? I'm pretty giddy about it. So, while I'm certainly not going to use my solar panels with my kitchen lights, if I had something along the lines of a joule thief that had infrared LEDs in it, it would be more effective than the florescent lights? I don't plan on making it, I'm just trying to wrap my head around this.
Kiteman5 years ago
It's a two-part answer; 1. Sunlight is brighter. 2. Sunlight is a different colour - it contains more of the high-energy violet end of the spectrum.
phalanx447 (author)  Kiteman5 years ago
I'm going to guess number two is the reason why colors of clothes in department stores look slightly different once you get them outside.
Correct - that effect is called metamerism. UK clothes store Marks and Spencer are devils for exploiting the effect - they specify that all the products they buy in look "right", and match each other, under the slightly greenish fluorescent lighting they use in the stores. When you have paid, they often don't look quite so good in daylight.
frollard5 years ago
On a bright day, the sun puts out a whopping 1000 watts PER SQUARE METER :D Our eyes automatically (if slowly) adjust to this, and we don't much notice the difference, but florescents output 'bright' light to our eyes, without using much energy. White light is made of many different wavelengths (or colours) of light. Our eyes are not equally sensitive to each of these wavelengths. Check out spectrometer images of sunlight (looks like a rainbow) versus a florescent bulb which outputs a mix of specific bands of colour. We perceive them as 'white' but there's a lot of energy missing.
kelseymh5 years ago
What Kiteman said and more. The full solar spectrum extends far beyond what you can see (visible light), including both infrared and ultraviolet. Fluorescent lights are built and tuned to have almost entirely visible-light output (any energy that goes into radiation you can't see is effectively wasted). The energy available to be converted by photovoltaic cells is dependent on the spectrum. Short wavelength, high frequency (violet and UV) photons carry more energy than long wavelengths. Hence, using natural light rather than "bandwidth limited" artificial lighting gives you more convertible energy input. You can see the violet/UV effect experimentally. Get some blacklights (which have a violet/UV spectrum) and turn them on along with your regular fluorescents. You should see higher output from your photovoltaic panels under those conditions.