New bulbs.

[Billcat]

Originally Posted by Cyfr

Solar cells do not simply work off any light. They only work off light with certain frequencies which happens to be the red end of the spectrum, hence they don't work as well with low energy bulbs because they give off more of the blue end of the spectrum which solar panels can't use.
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Well said, cyfr. And, while I am not an expert in the field, it would not suprise me to learn that it would be possible to build solar cells, ones that work better with the light spectrum from LE bulbs, for use in calculators and the like.

My area is finance, and I've done the calculations (based on US electricity prices) and the LE bulbs make financial sense - and will make even more sense as the price of electricity increases. I would expect that electricity in the UK probably costs more than it does here (based on the price of gasoline, another energy source), so LE bulbs probalby make even more sense over there. Also, I really like the fact that the LE bulbs burn out less frequently, in part because I like the convenience and set some value on my own time.

[jambutty]

Right i'll attempt again to explain it though my patience is thinning.

Am I supposed to tremble in my boots because your patience is thinning Cyfr. That’s a bit presumptuous isn’t it?

You can *not* use a calculator to determine how good or 'bright' a light source is.

Why not? In any case who the heck are you to tell me what I can and cannot do? A light meter, as used by photographers to determine the level of light falling on the subject, is nothing more than a solar panel in that the meter uses the light from the subject converted to a tiny electrical current to move a needle across a dial to indicate optimum aperture size and shutter speed settings.

So explain to me why when I spark up my fag lighter and hold the flame close to the solar panel the calculator works? The same goes for a candle flame or a flame from my gas stove. The glow from my computer monitor or TV screen. Explain to me why my calculator will not work the further away it is from any light source. Explain to me why my calculator will work with light from a blue bulb, a red one, a yellow one or a green one. I’ll grant you that I have to bring it closer to the source though. No doubt those coloured bulbs will also emit a little of the remaining colours but each bulb’s major emission will be in that colour. I don’t suppose that it would have anything to do with the intensity or brightness of the light would it?

You can't do this because calculators work from light energy.

Good! You finally agree with what I have been stating all along. The colour of light does not come into the equation just its brightness or as I prefer to call it the intensity.

All your blathering about the light spectrum is just a red herring.

Don't make such enormous assumptions such as "The energy consumed in making them compared to a normal bulb has to be more" because at the very least its a very misguided statement.

Here you go again trying to tell me what to do. Since when did you become my keeper?

[Less]

Cyfr you have my sympathy, instead of going down this dead end might I suggest you see how long you can keep hold of a 60W filament light bulb while it's switched on? It's about as useful, but just think how much relief you'll get when you let go.

[Lampman]

Come on lads,lights out!

[SPUGGIE J]

Originally Posted by Lampman

Come on lads,lights out!

Why are we to expect Gizmo and co for lunch???

[flashy]

i bought some of those bulbs from asda, 99p for 2

[SPUGGIE J]

Originally Posted by flashytart

i bought some of those bulbs from asda, 99p for 2

Only 2 you skinflint.

[flashy]

no you div, i was merely pointing out how much they are

[SPUGGIE J]

Originally Posted by flashytart

no you div, i was merely pointing out how much they are

And here was me thinking you were being a rebel. Oh which division am I then?

[andrewb]

Originally Posted by jambutty

Am I supposed to tremble in my boots because your patience is thinning Cyfr. That’s a bit presumptuous isn’t it?
Why not? In any case who the heck are you to tell me what I can and cannot do? A light meter, as used by photographers to determine the level of light falling on the subject, is nothing more than a solar panel in that the meter uses the light from the subject converted to a tiny electrical current to move a needle across a dial to indicate optimum aperture size and shutter speed settings.

I think it's ever so slightly silly to play the 'Who are you to tell me what to do' card when we're talking about how to conduct fair experiments here not how you should go about your daily life.

I don't have any knowledge of photography admittedly. I don't know how their light meters work but if it's from a solar cell, there are many different types. The one in your calculator is about 10% efficient in terms of how much of the spectrum it can use, where as roof type panels are 40-45% efficient.

Originally Posted by Jambutty

So explain to me why when I spark up my fag lighter and hold the flame close to the solar panel the calculator works? The same goes for a candle flame or a flame from my gas stove.

As previously stated, solar cells work best from red light wavelengths. Flames are incandescent in the same way filament bulbs are which means a lot of the light is from teh red end of the spectrum. Therefore your calculator will work fine from them.

Originally Posted by Jambutty

The glow from my computer monitor or TV screen.

I thought that would be rather obvious to you as you produced the information about RGB earlier in the thread. Red light is present, therefore your calculator works fine.

Originally Posted by Jambutty

Explain to me why my calculator will not work the further away it is from any light source.

The light spreads out as it gets greater distance. In the same way you can spray deodorant and it spreads out.

Originally Posted by Jambutty

Explain to me why my calculator will work with light from a blue bulb, a red one, a yellow one or a green one. I’ll grant you that I have to bring it closer to the source though. No doubt those coloured bulbs will also emit a little of the remaining colours but each bulb’s major emission will be in that colour. I don’t suppose that it would have anything to do with the intensity or brightness of the light would it?

I'll be honest and say I don't know. It should not work in blue light. I'm sure there is physics to explain it, like the efficiency of the filter, perhaps it allows some of the other wavelengths of light through but not many, hence explaining why you have to be close to the source.

Another reason could be any external light thats not coming from the blue light bulb such as light from another room, sunlight from the window, street lamps, anything.

Don't let this put you off the truth though, filters just arnt something I know about in enough detail to explain the anomaly. The rest however does explain that they work best from red light.

Originally Posted by Jambutty

Good! You finally agree with what I have been stating all along. The colour of light does not come into the equation just its brightness or as I prefer to call it the intensity.

I wasn't going to patronize you by making additions to what I was writing, I especially considered the sentence you quoted but assured myself that you would read the rest of my post in regards to the certain frequencies of light that solar cells work off. They work best off the red frequencies.

All your blathering about the light spectrum is just a red herring.

No, they're actually the key to the whole debate. The sooner you accept them the sooner you will realize why your calculator works less well with a low energy light bulb. They mainly emit a different kind of frequency which solar cells can't use.

[steeljack]

bit of a sidebar.....I dont think its a good idea for the wrinklies to be arguing the toss with the young uns, I think a bit more respect could be shown , considering that they are dependant on the financial contributions the young uns are making to pay for the pensions and benefits the owd uns enjoy .

[andrewb]

Too late to edit, but I can explain why it works through a blue bulb now.

I was under the impression that it didn't work at all with blue light, however it turns out that its just a LOT less efficient under light from the blue end of the spectrum as opposed to the light at the red end.

So if you are very close to the blue light source, it will work, but as I say you need to be closer as the solar cell is much less efficient at the blue end of the spectrum.

I think this pretty much clears everything up now.

[Ianto.W.]

Originally Posted by steeljack

bit of a sidebar.....I dont think its a good idea for the wrinklies to be arguing the toss with the young uns, I think a bit more respect could be shown , considering that they are dependant on the financial contributions the young uns are making to pay for the pensions and benefits the owd uns enjoy .

Off topic and cobblers, steeljack pensioners paid for their own pensions and contributed to educate these so called young uns, well out of order in my opinion.

[jambutty]

solar cells work best from red light wavelengths

If that is true how do you explain this?
Of visible light, violet has the most energy and red the least.
As stated on http://www.howstuffworks.com/light3.htm
Is a well respected site correct and you have got yourself mixed up or are you right and they are wrong?

I can make my computer screen into any colour I choose simply by either changing the boot up picture or running a paint package that covers the whole screen with a picture of any colour. Regardless of which colour I chose (except black or dark greys) my calculator will work.

The light spreads out as it gets greater distance.

Or the further away you get from a light source the less light there is to fall on a given area. Less light means not as bright.

Another reason could be any external light thats not coming from the blue light bulb such as light from another room, sunlight from the window, street lamps, anything.

It could be but it isn’t. I have already stated that the during the evenings with the curtains drawn the only light source is the table lamp on top of the TV and the glow from my monitor. As the monitor is in front of me and the calculator has to face me so that I can see the display ergo the solar panel is also facing the table lamp on top of the TV and cannot receive any light from the monitor.

They work best off the red frequencies.

In light of what I have stated at the beginning – prove your statement by pointing me to a bona fide web reference.

The sooner you accept them the sooner you will realize why your calculator works less well with a low energy light bulb.

But that is where all this started. I stated that the LE bulb would not make my calculator work unless I brought the calculator closer to the source. Therefore I concluded that the light from an LE bulb was not as bright as the light from an equivalent hot filament bulb. And now you agree with me.

Unless you can prove your “solar panels work best off red frequencies” statement as a proven scientific FACT then this post does clear up everything.

[andrewb]

Originally Posted by jambutty

If that is true how do you explain this?
Of visible light, violet has the most energy and red the least.
As stated on http://www.howstuffworks.com/light3.htm
Is a well respected site correct and you have got yourself mixed up or are you right and they are wrong?

They're right, i'm right, you have misunderstood them. Not once does it state how the light works with solar cells. The extra energy makes no difference, it is nowhere near as efficient with blue light.

Correct violet wavelengths are shorter and hence there is more energy. However i explicitly said that it's because of the way solar panels work and the efficiency of them as to why the blue end of the spectrum does not work very well. It doesn't matter how much energy they carry, it matters WHAT WORKS WITH SOLAR PANELS. Which is undoubtedly the red end of the spectrum.

Check http://www.iee.cz/iwtpv04/6-Pociask.ppt slide number 32. Much more efficient type of cell than yours, but you get the picture. The lower the wavelength the lower the efficiency. Blue light has a shorter wavelength = not as efficient with solar cells.

This does clear it up. It is scientific fact that solar cells are not as efficient with the lower end of the spectrum. It showed up on the first google link about the subject, however I did have to do some searching to get a graph to visually display it.

I do hope you'll finally accept it because i've wrote a heck of a lot on this thread in an effort to explain things to you.