Photodiode / Phototransistor Measuring Sunlight

I'm in need of some quick help. Can anyone recommend a photodiode or phototransister that I would be able to measure sunlight with. Ideally I would like to be able to measure from 500 to 30,000 Lux. Right now I have a sensor that is only accurate up to about 1000 lux.

Other suggestions to measure sunlight are appreciated too as long as they are not too complex and do not cost a lot.

Green LEDS are used for solar panel trackers.
I do not know its maximum but it is cheap.

Thats quite a good answer has the questionare ever thought about taking a slr camera apart for use as a light meter Green leds work quite well If the sensitivity is down why not amplify your signal in

I forgot to say you need a transparent housing for the LED.
And the nice trick a colored led is sensitize to its color.

See also the below pdf that explains more did you know that key board leds are also used for measuring the light or in a fiberglass cable the same transmitter can also be used as receiver.

Considering that John is looking for a quantitative source, I wonder if the output of a Green LED (or solar cell, even) is constant over temperature. Just something to consider.

Having no idea myself, I would research the following as viable quantitative photodetectors:

* Solar Cell
* Photo Resistor (LDR)
* Reverse Biased LED
* PIN diode

You can probably control sensitivity at the upper end with different sized apertures and at the lower end with a lens or lenses or a curved reflector (e.g. parabolic). Also, if there is temperature drift you might be able to compensate with a thermistor or a duplicate sensor kept in the dark or under a constant light source and inserted in the adjacent leg of a wheatstone bridge.

I have no experience with this, so I'm just thinking out loud

Thanks everyone for the suggestions. This too is new territory to me, my primary focus while I've been in school is a mixture of high frequency design and microcontrollers/programming. As far as sensors, power, etc. I've had to learn most of it on my own.

I have my hands currently on a photoresistor, solar cell, and several different LEDs. How would the green LED work to sense light. I assume it would be reversed biased. Would it be something like using the LED in reverse bias in a voltage divider network and then I would be able to measure the varying voltage drop across the LED as the light increased?

The LED will actually produce a voltage. Try connecting one to a volt meter and point it at the sun and see what happens

And actually, it might be more a function of current, so try connecting it to a current meter. I suspect the current transfer function would be more useful.

Very interesting, I will definitely have to do this soon. Thanks!