Newbie: Small solar panel and LED lights (question)

[sustainablecapston]

Hi. I'm a graduate student working on a capstone about sustainable design. This being said, I'm no engineer so this topic is somewhat overwhelming. I'm hoping you kind folks can help me. I've been researching DIY solar panels. I want to make a cube out of frosted plexiglass with LED's on the inside and solar panels on the back and place it in a window sill. Will it get enough light to store enough energy to light the LED's at night. Now I'm talking a small cube like 6 inches x 6 inches (give and take a few inches) The idea is that the cube will be portable and provide light at night. I don't understand electricity very much so I don't know how much power one solar panel can store and I don't know how much power 12 LEDs would use. IF it is possible, how long will that light last before it runs out of energy. I've got a schematic drawn up and I'd be willing to share with anyone who wants to help me tackle this project. (i don't feel safe posting it here) Thanks for your help.

[Tavi]

solar panels don't store energy. they just produce it, you will need a battery to store the energy from the panel and it depends on the leds you use: size. type. etc to calculate how much they need but 95% you will need at least 5 amps to keep them up for 12h just on battery, you will need a light detector suck as a photocell to see if it's day/night since you will want them turned off during daytime and you will need a solar cell that puts out around 1.5 volts to charge up the 1.2 v battery.

ps : nice ideea, and good luck whit it

[inetdog]

you will need a light detector suck as a photocell to see if it's day/night since you will want them turned off during daytime and you will need a solar cell that puts out around 1.5 volts to charge up the 1.2 v battery.
ps : nice ideea, and good luck whit it

If you are clever with your electronics, you can just use the output from the solar cell to detect day/night instead of adding a separate photocell.
Putting a solar cell behind a glass window (and not aiming the cell directly at the sun, off by more than say 30 degrees) will drastically cut the amount of incoming solar energy. If you can set the cube outside, and not in the shade, it would be more efficient.

[Tavi]

If you are clever with your electronics, you can just use the output from the solar cell to detect day/night instead of adding a separate photocell.
Putting a solar cell behind a glass window (and not aiming the cell directly at the sun, off by more than say 30 degrees) will drastically cut the amount of incoming solar energy. If you can set the cube outside, and not in the shade, it would be more efficient.

i know that but i was thinking since you can only fit 1 poorly lid cell you will need all the power it can give and a transistor that would act like a switch for the leds will take up some of the power while a photodiode is selfpowered.

[inetdog]

i know that but i was thinking since you can only fit 1 poorly lid cell you will need all the power it can give and a transistor that would act like a switch for the leds will take up some of the power while a photodiode is selfpowered.

A photodiode is, in effect, a very small solar cell. The amount of power that it can produce will be correspondingly small. A circuit which makes use of the photodiode output will have to work with that minimal amount of power, and so could work just as economically from the cell itself.